On the other hand it is the right operator to use for color stretching gradient images being used to generate Color lookup tables, distortion maps, or other 'mathematically' defined images. The operator is very similar to the -normalize , -contrast-stretch , and -linear-stretch operators, but without 'histogram binning' or 'clipping' problems that these operators may have.

That is -auto-level is the perfect or ideal version these operators. It uses the -channel setting, including the special ' sync ' flag for channel synchronization , to determine which color values are used and modified.

Adjusts an image so that its orientation is suitable for viewing i. top-left orientation. This operator reads and resets the EXIF image profile setting 'Orientation' and then performs the appropriate 90 degree rotation on the image to orient the image, for correct viewing.

This EXIF profile setting is usually set using a gravity sensor in digital camera, however photos taken directly downward or upward may not have an appropriate value. Also images that have been orientation 'corrected' without reseting this setting, may be 'corrected' again resulting in a incorrect result. If the EXIF profile was previously stripped, the -auto-orient operator will do nothing.

The computed threshold is returned as the auto-threshold:verbose image property. This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the background color. The color is specified using the format described under the -fill option. The default background color if none is specified or found in the image is white.

Repeat the entire command for the given number of iterations and report the user-time and elapsed time. For instance, consider the following command and its output. Modify the benchmark with the -duration to run the benchmark for a fixed number of seconds and -concurrent to run the benchmark in parallel requires the OpenMP feature.

In this example, 5 iterations were completed at 2. This option shifts the output of -convolve so that positive and negative results are relative to the specified bias value. This is important for non-HDRI compilations of ImageMagick when dealing with convolutions that contain negative as well as positive values. This is especially the case with convolutions involving high pass filters or edge detection. Without an output bias, the negative values are clipped at zero.

See the discussion on HDRI implementations of ImageMagick on the page High Dynamic-Range Images. For more about HDRI go the ImageMagick Usage pages or this Wikipedia entry. A non-linear, edge-preserving, and noise-reducing smoothing filter for images.

It replaces the intensity of each pixel with a weighted average of intensity values from nearby pixels. This weight is based on a Gaussian distribution. The weights depend not only on Euclidean distance of pixels, but also on the radiometric differences e. This preserves sharp edges.

The intensity sigma is in the intensity space. A larger value means that farther colors within the pixel neighborhood see spatial-sigma will be mixed together, resulting in larger areas of semi-equal color.

The spatial sigma is in the coordinate space. A larger value means that farther pixels influence each other as long as their colors are close enough see intensity-sigma. When the neigborhood diameter is greater than zero, it specifies the neighborhood size regardless of spatial-sigma. Otherwise, the neigborhood diameter is proportional to spatial-sigma. The default value for the intensity and spatial sigmas are 0.

Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged. The threshold value can be given as a percentage or as an absolute integer value within [0, QuantumRange ] corresponding to the desired -channel value. See -threshold for more details on thresholds and resulting values. Blend will average the images together 'plus' according to the percentages given and each pixels transparency. If only a single percentage value is given it sets the weight of the composite or 'source' image, while the background image is weighted by the exact opposite amount.

Simulate a scene at nighttime in the moonlight. Start with a factor of 1. Convolve the image with a Gaussian or normal distribution using the given Sigma value. The formula is:. The larger the Radius the slower the operation is. However too small a Radius , and severe aliasing effects may result. As a guideline, Radius should be at least twice the Sigma value, though three times will produce a more accurate result. This option differs from -gaussian-blur simply by taking advantage of the separability properties of the distribution.

Here we apply a single-dimensional Gaussian matrix in the horizontal direction, then repeat the process in the vertical direction. The -virtual-pixel setting will determine how pixels which are outside the image proper are blurred into the final result.

Set the width and height using the size portion of the geometry argument. Offsets are ignored. The -border operation is affected by the current -compose setting and assumes that this is using the default ' Over ' composition method.

It generates an image of the appropriate size colors by the current -bordercolor before overlaying the original image in the center of this net image. This means that with the default compose method of ' Over ' any transparent parts may be replaced by the current -bordercolor setting. The default border color is DFDFDF , this shade of gray. Brightness and Contrast values apply changes to the input image. They are not absolute settings. A brightness or contrast value of zero means no change.

Positive values increase the brightness or contrast and negative values decrease the brightness or contrast. The default is to apply the same transformation to all channels. Brightness and Contrast arguments are converted to offset and slope of a linear transform and applied using -function polynomial "slope,offset".

Negative slopes, i. negating the image, are not possible with this function. All achievable slopes are zero or positive. The offset varies from This option has been replaced by the -limit option. Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.

The default thresholds are shown. The radius {x sigma } controls a gaussian blur applied to the input image to reduce noise and smooth the edges. This option sets the caption meta-data of an image read in after this option has been given. To modify a caption of images already in memory use " -set caption ". The caption can contain special format characters listed in the Format and Print Image Properties. These attributes are expanded when the caption is finally assigned to the individual images.

If the first character of string is , the image caption is read from a file titled by the remaining characters in the string. Comments read in from a file are literal; no embedded formatting characters are recognized. Caption meta-data is not visible on the image itself. To do that use the -annotate or -draw options instead. produces an image caption of MIFF:bird. miff x assuming that the image bird. miff has a width of and a height of Specify those image color channels to which subsequent operators are limited.

Choose from: Red , Green , Blue , Alpha , Gray , Cyan , Magenta , Yellow , Black , Opacity , Index , RGB , RGBA , CMYK , or CMYKA. The channels above can also be specified as a comma-separated list or can be abbreviated as a concatenation of the letters ' R ', ' G ', ' B ', ' A ', ' O ', ' C ', ' M ', ' Y ', ' K '.

The numerals 0 to 31 may also be used to specify channels, where 0 to 5 are: ' 0 ' equals Red or Cyan ' 1 ' equals Green or Magenta ' 2 ' equals Blue or Yellow ' 3 ' equals Black ' 4 ' equals Alpha or Opacity ' 5 ' equals Index.

For example, to only select the Red and Blue channels you can use any of the following:. All the channels that are present in an image can be specified using the special channel type All. Not all operators are 'channel capable', but generally any operators that are generally 'grey-scale' image operators, will understand this setting.

See individual operator documentation. On top of the normal channel selection an extra flag can be specified, ' Sync '. This is turned on by default and if set means that operators that understand this flag should perform: cross-channel synchronization of the channels. If not specified, then most grey-scale operators will apply their image processing operations to each individual channel as specified by the rest of the -channel setting completely independently from each other.

For example for operators such as -auto-level and -auto-gamma the color channels are modified together in exactly the same way so that colors will remain in-sync. Without it being set, then each channel is modified separately and independently, which may produce color distortion. The -morphology ' Convolve ' method and the -compose mathematical methods, also understands the ' Sync ' flag to modify the behavior of pixel colors according to the alpha channel if present.

That is to say it will modify the image processing with the understanding that fully-transparent colors should not contribute to the final result. Basically, by default, operators work with color channels in synchronous, and treats transparency as special, unless the -channel setting is modified so as to remove the effect of the ' Sync ' flag.

How each operator does this depends on that operators current implementation. Not all operators understands this flag at this time, but that is changing.

By default, ImageMagick sets -channel to the value ' RGBK,sync ', which specifies that operators act on all color channels except the transparency channel, and that all the color channels are to be modified in exactly the same way, with an understanding of transparency depending on the operation being applied.

Options that are affected by the -channel setting include the following. These operators have yet to be made to understand the newer 'Sync' flag. For example -threshold will by default grayscale the image before thresholding, if no -channel setting has been defined. This is not 'Sync flag controlled, yet. Also some operators such as -blur , -gaussian-blur , will modify their handling of the color channels if the ' alpha ' channel is also enabled by -channel.

Generally this done to ensure that fully-transparent colors are treated as being fully-transparent, and thus any underlying 'hidden' color has no effect on the final results.

Typically resulting in 'halo' effects. The newer -morphology convolution equivalents however does have a understanding of the 'Sync' flag and will thus handle transparency correctly by default. As an alpha channel is optional within images, some operators will read the color channels of an image as a greyscale alpha mask, when the image has no alpha channel present, and the -channel setting tells the operator to apply the operation using alpha channels.

The -clut operator is a good example of this. The expression consists of one or more channels, either mnemonic or numeric e. red or 0, green or 1, etc.

For example, to create 3 grayscale images from the red, green, and blue channels of an image, use:. Here we take an sRGB image and a grayscale image and inject the grayscale image into the alpha channel:.

Add -debug pixel prior to the -channel-fx option to track the channel morphology. The width and height given in the of the size portion of the geometry argument give the number of columns and rows to remove. The offset portion of the geometry argument is influenced by a -gravity setting, if present. The -chop option removes entire rows and columns, and moves the remaining corner blocks leftward and upward to close the gaps. While it can remove internal rows and columns of pixels, it is more typically used with as -gravity setting and zero offsets so as to remove a single edge from an image.

Compare this to -shave which removes equal numbers of pixels from opposite sides of the image. Using -chop effectively undoes the results of a -splice that was given the same geometry and -gravity settings. The image is divided into tiles of width and height pixels.

The tile size should be larger than the size of features to be preserved and respects the aspect ratio of the image. to force an exact tile width and height.

number-bins is the number of histogram bins per tile min 2, max The number of histogram bins should be smaller than the number of pixels in a single tile. clip-limit is the contrast limit for localized changes in contrast. A clip-limit of 2 to 3 is a good starting place e. Very large values will let the histogram equalization do whatever it wants to do, that is result in maximal local contrast. The value 1 will result in the original image.

Note, if the number of bins and the clip-limit are ommitted, they default to and no clipping respectively. Set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range e. The -clip feature requires SVG support. If the SVG delegate library is not present, the option is ignored.

Use the alpha channel of the current image as a mask. Any areas that is white is not modified by any of the 'image processing operators' that follow, until the mask is removed. Pixels in the black areas of the clip mask are modified per the requirements of the operator. In some ways this is similar to though not the same as defining a rectangular -region , or using the negative of the mask third image in a three image -composite , operation.

This is identical to -clip except choose a specific clip path in the event the image has more than one path available. ImageMagick supports UTF-8 encoding. Inside parenthesis where the operator is normally used it will make a clone of the images from the last 'pushed' image sequence, and adds them to the end of the current image sequence.

Outside parenthesis not recommended it clones the images from the current image sequence. Specify the image by its index in the sequence. The first image is index 0. Specify a range of images with a dash e. Separate multiple indexes with commas but no spaces e. Replace the channel values in the first image using each corresponding channel in the second image as a c olor l ook u p t able.

The second LUT image is ordinarily a gradient image containing the histogram mapping of how each channel should be modified. Typically it is a either a single row or column image of replacement color values. If larger than a single row or column, values are taken from a diagonal line from top-left to bottom-right corners. The lookup is further controlled by the -interpolate setting, which is especially handy for an LUT which is not the full length needed by the ImageMagick installed Quality Q level.

Good settings for this are ' bilinear ' and ' catrom '. Catom can return a useful second-order continuity. This operator is especially suited to replacing a grayscale image with a specific color gradient from the CLUT image. Only the channel values defined by the -channel setting will have their values replaced. If either the image being modified, or the lookup image, contains no transparency i.

That is you can use a grayscale CLUT image to adjust a existing images alpha channel, or you can color a grayscale image using colors form CLUT containing the desired colors, including transparency. See also -hald-clut which replaces colors according to the lookup of the full color RGB value from a 2D representation of a 3D color cube. Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.

Overlay each image in an image sequence according to its -dispose meta-data, to reproduce the look of an animation at each point in the animation sequence. All images should be the same size, and are assigned appropriate GIF disposal settings for the animation to continue working as expected as a GIF animation.

Such frames are more easily viewed and processed than the highly optimized GIF overlay images. The animation can be re-optimized after processing using the -layers method ' optimize ', although there is no guarantee that the restored GIF animation optimization is better than the original. Colorize the image by an amount specified by value using the color specified by the most recent -fill setting. Specify the amount of colorization as a percentage.

Separate colorization values can be applied to the red, green, and blue channels of the image with a comma-delimited list of colorization values e. This option only applies when the default X server visual is PseudoColor or GrayScale.

Refer to -visual for more details. By default, a shared colormap is allocated. The image shares colors with other X clients. Some image colors could be approximated, therefore your image may look very different than intended. If private is chosen, the image colors appear exactly as they are defined. However, other clients may go technicolor when the image colormap is installed. The actual number of colors in the image may be less than your request, but never more.

Note that this a color reduction option. Images with fewer unique colors than specified by value will have any duplicate or unused colors removed. The ordering of an existing color palette may be altered. When converting an image from color to grayscale, it is more efficient to convert the image to the gray colorspace before reducing the number of colors. Refer to the color reduction algorithm for more details. This option permits saturation changes, hue rotation, luminance to alpha, and various other effects.

Although variable-sized transformation matrices can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6 for CMYKA or RGBA with offsets. The matrix is similar to those used by Adobe Flash except offsets are in column 6 rather than 5 in support of CMYKA images and offsets are normalized divide Flash offset by For a more accurate color conversion to or from the linear RGB, CMYK, or grayscale colorspaces, use the -profile option.

Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise. For colorspace conversion, the gamma function is first removed to produce linear RGB. Return a binary image where all colors within the specified range are changed to white.

All other colors are changed to black. The channels previously set by -channel of the combined image are taken from the grayscale values of each image in the sequence, in order. For the default -channel setting of RGB , this means the first image is assigned to the Red channel, the second to the Green channel, the third to the Blue. This option can be thought of as the inverse to -separate , so long as the channel settings are the same.

Thus, in the following example, the final image should be a copy of the original. This option sets the comment meta-data of an image read in after this option has been given. To modify a comment of images already in memory use " -set comment ". The comment can contain special format characters listed in the Format and Print Image Properties.

These attributes are expanded when the comment is finally assigned to the individual images. If the first character of string is , the image comment is read from a file titled by the remaining characters in the string.

Comment meta-data are not visible on the image itself. produces an image comment of MIFF:bird. Mathematically and visually annotate the difference between an image and its reconstruction. This is a convert version of " compare " for two same sized images. The syntax is as follows, but other metrics are allowed.

See Alpha Compositing for a detailed discussion of alpha compositing. This setting affects image processing operators that merge two or more images together in some way. This includes the operators, -compare , -composite , -layers composite, -flatten , -mosaic , -layers merge, -border , -frame , and -extent.

Take the first image 'destination' and overlay the second 'source' image according to the current -compose setting. The location of the 'source' or 'overlay' image is controlled according to -gravity , and -geometry settings. If a third image is given this is treated as a grayscale blending 'mask' image relative to the first 'destination' image. This mask is blended with the source image. However for the ' displace ' compose method, the mask is used to provide a separate Y-displacement image instead.

If a -compose method requires extra numerical arguments or flags these can be provided by setting the -set ' option:compose:args ' appropriately for the compose method. Some -compose methods can modify the 'destination' image outside the overlay area. It is disabled by default.

The SVG compositing specification requires that color and opacity values range between zero and QuantumRange inclusive. Use pixel compression specified by type when writing the image.

Choices are: None , BZip , Fax , Group4 , JPEG , JPEG , Lossless , LZW , RLE or Zip. The default is the compression type of the specified image file. If LZW compression is specified but LZW compression has not been enabled, the image data is written in an uncompressed LZW format that can be read by LZW decoders.

This may result in larger-than-expected GIF files. Lossless refers to lossless JPEG, which is only available if the JPEG library has been patched to support it.

Use of lossless JPEG is generally not recommended. When writing an ICO file, you may request that the images be encoded in PNG format, by specifying Zip compression. When writing a JNG file, specify Zip compression to request that the alpha channel be encoded in PNG "IDAT" format, or JPEG to request that it be encoded in JPG "JDAA" format.

Use the -quality option to set the compression level to be used by JPEG, PNG, MIFF, and MPEG encoders. Use the -sampling-factor option to set the sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling the chroma channels. connected-components labeling detects connected regions in an image, choose from 4 or 8 way connectivity. This option enhances the intensity differences between the lighter and darker elements of the image.

Increase the contrast in an image by stretching the range of intensity values. While performing the stretch, black-out at most black-point pixels and white-out at most white-point pixels. Prior to ImageMagick 6.

Note that -contrast-stretch 0 will modify the image such that the image's min and max values are stretched to 0 and QuantumRange , respectively, without any loss of data due to burn-out or clipping at either end.

This is not the same as -normalize , which is equivalent to -contrast-stretch 0. Internally operator works by creating a histogram bin, and then uses that bin to modify the image. As such some colors may be merged together when they originally fell into the same 'bin'. Specifying any other -channel setting will normalize the RGB channels independently.

See also -auto-level for a 'perfect' normalization of mathematical images. The kernel is a matrix specified as a comma-separated list of integers with no spaces , ordered left-to right, starting with the top row. Note that the -convolve operator supports the -bias setting. This option shifts the convolution so that positive and negative results are relative to a user-specified bias value. Without an output bias, the negative values is clipped at zero.

The width and height of the geometry argument give the size of the image that remains after cropping, and x and y in the offset if present gives the location of the top left corner of the cropped image with respect to the original image. To specify the amount to be removed, use -shave instead. If the x and y offsets are present, a single image is generated, consisting of the pixels from the cropping region. The offsets specify the location of the upper left corner of the cropping region measured downward and rightward with respect to the upper left corner of the image.

If the -gravity option is present with NorthEast , East , or SouthEast gravity, it gives the distance leftward from the right edge of the image to the right edge of the cropping region.

Similarly, if the -gravity option is present with SouthWest , South , or SouthEast gravity, the distance is measured upward between the bottom edges. If the x and y offsets are omitted, a set of tiles of the specified geometry, covering the entire input image, is generated.

The rightmost tiles and the bottom tiles are smaller if the specified geometry extends beyond the dimensions of the input image. You can add the to the geometry argument to equally divide the image into the number of tiles generated.

By adding a exclamation character flag to the geometry argument, the cropped images virtual canvas page size and offset is set as if the geometry argument was a viewport or window. This means the canvas page size is set to exactly the same size you specified, the image offset set relative top left corner of the region cropped. If the cropped image 'missed' the actual image on its virtual canvas, a special single pixel transparent 'missed' image is returned, and a 'crop missed' warning given.

This is especially true when you are going to write to an image format such as PNG that supports an image offset. The events parameter specifies which events are to be logged. It can be either None , All , Trace , or a comma-separated list consisting of one or more of the following domains: Accelerate , Annotate , Blob , Cache , Coder , Configure , Deprecate , Exception , Locale , Render , Resource , Security , TemporaryFile , Transform , X11 , or User.

The User domain is normally empty, but developers can log user events in their private copy of ImageMagick. Decipher and restore pixels that were previously transformed by -encipher. For more information, see the webpage, ImageMagick: Encipher or Decipher an Image. Given a sequence of images all the same size, such as produced by -coalesce , replace the second and later images, with a smaller image of just the area that changed relative to the previous image.

The resulting sequence of images can be used to optimize an animation sequence, though will not work correctly for GIF animations when parts of the animation can go from opaque to transparent. This option is actually equivalent to the -layers method ' compare-any '.

Add specific global settings generally used to control coders and image processing operations. This option creates one or more definitions for coders and decoders to use while reading and writing image data. Definitions are generally used to control image file format coder modules, and image processing operations, beyond what is provided by normal means.

Defined settings are listed in -verbose information " info: " output format as "Artifacts". If value is missing for a definition, an empty-valued definition of a flag is created with that name. The same 'artifact' settings can also be defined using the -set "option: key " " value " option, which also allows the use of Format and Print Image Properties in the defined value.

The option and key are case-independent they are converted to lowercase for use within the decoders while the value is case-dependent. See ImageMagick Defines for a list of recognized defines. For example:. Set attributes of the image registry by prefixing the value with registry:. For example, to set a temporary path to put work files, use:. The default is no delay between each showing of the image sequence.

The default ticks-per-second is However, if the image delay is 40 or 50, the delay it is changed to Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Separate indexes with a comma e. Use -delete to delete the entire image sequence. You can also delete images from the persistent registry, e. Set the horizontal and vertical resolution of an image for rendering to devices.

This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering reading vector formats such as Postscript, PDF, WMF, and SVG into a raster image. Image resolution provides the unit of measure to apply when rendering to an output device or raster image. The default unit of measure is in dots per inch DPI. The -units option may be used to select dots per centimeter instead.

The default resolution is 72 dots per inch, which is equivalent to one point per pixel Macintosh and Postscript standard. Computer screens are normally 72 or 96 dots per inch, while printers typically support , , , or dots per inch. To determine the resolution of your display, use a ruler to measure the width of your screen in inches, and divide by the number of horizontal pixels on a x display. If the file format supports it, this option may be used to update the stored image resolution.

Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile is not stripped from the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.

The -density option sets an attribute and does not alter the underlying raster image. It may be used to adjust the rendered size for desktop publishing purposes by adjusting the scale applied to the pixels. To resize the image so that it is the same size at a different resolution, use the -resample option. Color depth is the number of bits per channel for each pixel.

Use this option to specify the depth of raw images formats whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.

Use -set option:deskew:auto-crop true false to auto crop the image. Render text right-to-left or left-to-right. Requires the RAQM delegate library and complex text layout. With this option, the 'overlay' image, and optionally the 'mask' image, is used as a displacement map, which is used to displace the lookup of what part of the 'background' image is seen at each point of the overlaid area. Much like the displacement map is a 'lens' that redirects light shining through it so as to present a distorted view the original 'background' image behind it.

Any perfect grey areas of the displacement map produce a zero displacement of the image. Black areas produce the given maximum negative displacement of the lookup point, while white produce a maximum positive displacement of the lookup.

Note that it is the lookup of the 'background' that is displaced, not a displacement of the image itself. Understanding this is a very important in understanding how displacement maps work. The given arguments define the maximum amount of displacement in pixels that a particular map can produce. If the displacement scale is large enough it is also possible to lookup parts of the 'background' image that lie well outside the bounds of the displacement map itself.

That is you could very easily copy a section of the original image from outside the overlay area into the overlay area. Using '! these flags were added as of IM v6. Normally a single grayscale displacement map is provided, which with the given scaling values will determine a single direction vector in which displacements can occur positively or negatively. However, if you also specify a third image which is normally used as a mask , the composite image is used for horizontal X displacement, while the mask image is used for vertical Y displacement.

This allows you to define completely different displacement values for the X and Y directions, and allowing you to lookup any point within the scale bounds. In other words each pixel can lookup any other nearby pixel, producing complex 2 dimensional displacements, rather than a simple 1 dimensional vector displacements.

Alternatively rather than supplying two separate images, as of IM v6. As of IM v6. However areas outside the overlaid areas will not be affected. This option is used with convert for obtaining image or font from this X server.

See X 1. Define the GIF disposal image setting for images that are being created or read in. The layer disposal method defines the way each the displayed image is to be modified after the current 'frame' of an animation has finished being displayed after its 'delay' period , but before the next frame on an animation is to be overlaid onto the display.

You can also use the numbers given above, which is what the GIF format uses internally to represent the above settings. Use -set ' dispose ' method to set the image disposal method for images already in memory. The opacity of the composite image is multiplied by the given percent, then it is composited 'over' the main image.

If both percentages are given, each image are dissolved to the percentages given. Distort an image, using the given method and its required arguments. The arguments is a single string containing a list of floating point numbers separated by commas or spaces. The number of and meaning of the floating point values depends on the distortion method being used.

Many of the above distortion methods such as ' Affine ', ' Perspective ', and ' Shepards ' use a list control points defining how these points in the given image should be distorted in the destination image.

Each set of four floating point values represent a source image coordinate, followed immediately by the destination image coordinate.

This produces a list of values such as For example, to warp an image using ' perspective ' distortion, needs a list of at least 4 sets of coordinates, or 16 numbers.

Here is the perspective distortion of the built-in "rose:" image. Note how spaces were used to group the 4 sets of coordinate pairs, to make it easier to read and understand.

If more that the required number of coordinate pairs are given for a distortion, the distortion method is 'least squares' fitted to produce the best result for all the coordinate pairs given. If less than the ideal number of points are given, the distort will generally fall back to a simpler form of distortion that can handles the smaller number of coordinates usually a linear ' Affine ' distortion.

By using more coordinates you can make use of image registration tool to find matching coordinate pairs in overlapping images, so as to improve the 'fit' of the distortion. Of course a bad coordinate pair can also make the 'fit' worse. Caution is always advised. Colors are acquired from the source image according to a cylindrical resampling -filter , using a special technique known as EWA resampling.

This produces very high quality results, especially when images become smaller minified in the output, which is very common when using ' perspective ' distortion. For example here we view a infinitely tiled 'plane' all the way to the horizon. Note that a infinitely tiled perspective images involving the horizon can be very slow, because of the number of pixels that are compressed to generate each individual pixel close to the 'horizon'.

You can turn off EWA resampling, by specifying the special -filter setting of ' point ' recommended if you plan to use super-sampling instead.

If an image generates invalid pixels , such as the 'sky' in the last example, -distort will use the current -mattecolor setting for these pixels. If you do not what these pixels to be visible, set the color to match the rest of the ground. The output image size will by default be the same as the input image.

This means that if the part of the distorted image falls outside the viewed area of the 'distorted space', those parts is clipped and lost. Setting -verbose setting, will cause -distort to attempt to output the internal coefficients, and the -fx equivalent to the distortion, for expert study, and debugging purposes. This many not be available for all distorts. This can be used either for 'super-sampling' the image for a higher quality result, or for panning and zooming around the image with appropriate viewport changes, or post-distort cropping and resizing.

Note this table uses a squared radius lookup value. This is typically only used for debugging EWA resampling. Apply a Riemersma or Floyd-Steinberg error diffusion dither to images when general color reduction is applied via an option, or automagically when saving to specific formats. This enabled by default. Dithering places two or more colors in neighboring pixels so that to the eye a closer approximation of the images original color is reproduced.

This reduces the number of colors needed to reproduce the image but at the cost of a lower level pattern of colors. Error diffusion dithers can use any set of colors generated or user defined to an image. This will also render PostScript without text or graphic aliasing.

Disabling dithering often but not always leads to faster process, a smaller number of colors, but more cartoon like image coloring. Generally resulting in 'color banding' effects in areas with color gradients. The color reduction operators -colors , -monochrome , -remap , and -posterize , apply dithering to images using the reduced color set they created.

These operators are also used as part of automatic color reduction when saving images to formats with limited color support, such as GIF: , XBM: , and others, so dithering may also be used in these cases.

Alternatively you can use -random-threshold to generate purely random dither. Or use -ordered-dither to apply threshold mapped dither patterns, using uniform color maps, rather than specific color maps. Use this option to annotate or decorate an image with one or more graphic primitives. The primitives include shapes, text, transformations, and pixel operations. The text gravity primitive only affects the placement of text and does not interact with the other primitives.

It is equivalent to using the -gravity command-line option, except that it is limited in scope to the -draw option in which it appears. The shape primitives are drawn in the color specified by the preceding -fill setting. For unfilled shapes, use -fill none. You can optionally control the stroke the "outline" of a shape with the -stroke and -strokewidth settings. A point primitive is specified by a single point in the pixel plane, that is, by an ordered pair of integer coordinates, x , y.

As it involves only a single pixel, a point primitive is not affected by -stroke or -strokewidth. A rectangle primitive is specified by the pair of points at the upper left and lower right corners. A roundRectangle primitive takes the same corner points as a rectangle followed by the width and height of the rounded corners to be removed. The circle primitive makes a disk filled or circle unfilled. Give the center and any point on the perimeter boundary.

Note, by using a translation, you can remove the need to calculate the circles edge coordinate, but can just give the radius directly:. The arc primitive is used to inscribe an elliptical segment in to a given rectangle. An arc requires the two corners used for rectangle see above followed by the start and end angles of the arc of the segment e. The start and end points produced are then joined with a line segment and the resulting segment of an ellipse is filled.

Use ellipse to draw a partial or whole ellipse. Give the center point, the horizontal and vertical "radii" the semi-axes of the ellipse and start and end angles in degrees e.

The polyline and polygon primitives require three or more points to define their perimeters. A polyline is simply a polygon in which the final point is not stroked to the start point. When unfilled, this is a polygonal line. If the -stroke setting is none the default , then a polyline is identical to a polygon. The Bezier primitive creates a spline curve and requires three or points to define its shape.

The first and last points are the knots and these points are attained by the curve, while any intermediate coordinates are control points. If two control points are specified, the line between each end knot and its sequentially respective control point determines the tangent direction of the curve at that end.

If one control point is specified, the lines from the end knots to the one control point determines the tangent directions of the curve at each end. If more than two control points are specified, then the additional control points act in combination to determine the intermediate shape of the curve. In order to draw complex curves, it is highly recommended either to use the path primitive or to draw multiple four-point bezier segments with the start and end knots of each successive segment repeated.

A path represents an outline of an object, defined in terms of moveto set a new current point , lineto draw a straight line , curveto draw a Bezier curve , arc elliptical or circular arc and closepath close the current shape by drawing a line to the last moveto elements. Compound paths i. See Paths. Use image to composite an image with another image. Follow the image keyword with the composite operator, image location, image size, and filename:. You can use 0,0 for the image size, which means to use the actual dimensions found in the image header.

Otherwise, it is scaled to the given dimensions. See Alpha Compositing for a detailed discussion of alpha composition methods that are available. The "special augmented compose operators" such as "dissolve" that require arguments cannot be used at present with the -draw image option. Use text to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in single or double quotes. For example, the following annotates the image with Works like magick!

for an image titled bird. See the -annotate option for another convenient way to annotate an image with text. The rotate primitive rotates subsequent shape primitives and text primitives about the origin of the main image:. The skewX and skewY primitives skew them with respect to the origin of the main image or the region.

The transformations modify the current affine matrix, which is initialized from the initial affine matrix defined by the -affine option. Transformations are cumulative within the -draw option. The initial affine matrix is not affected; that matrix is only changed by the appearance of another -affine option.

If another -draw option appears, the current affine matrix is reinitialized from the initial affine matrix.

Use the color primitive to change the color of a pixel to the fill color see -fill. Follow the pixel coordinate with a method:.

Consider the target pixel as that specified by your coordinate. The point method recolors the target pixel. The replace method recolors any pixel that matches the color of the target pixel. Floodfill recolors any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder recolors any neighbor pixel that is not the border color. Finally, reset recolors all pixels. Use matte to the change the pixel matte value to transparent.

Follow the pixel coordinate with a method see the color primitive for a description of methods. The point method changes the matte value of the target pixel. The replace method changes the matte value of any pixel that matches the color of the target pixel.

Floodfill changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder changes the matte value of any neighbor pixel that is not the border color -bordercolor. Finally reset changes the matte value of all pixels. You can set the primitive color, font, and font bounding box color with -fill , -font , and -box respectively. Options are processed in command line order so be sure to use these options before the -draw option.

Drawing primitives conform to the Magick Vector Graphics format. Note, drawing requires an alpha channel. If none is available, an all opaque alpha channel is implicitedly created. Specify the count and the image to duplicate by its index in the sequence. Encipher pixels for later deciphering by -decipher. Specify endianness MSB or LSB of the image. To perform histogram equalization on all channels in concert, transform the image into some other color space, such as HSL, OHTA, YIQ or YUV, then equalize the appropriate intensity-like channel, then convert back to RGB.

For example using HSL, we have For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal components transformation that puts most of the information in the first channel. Here we have Alter channel pixels by evaluating an arithmetic, relational, or logical expression. See the -function operator for some multi-parameter functions. See the -fx operator if more elaborate calculations are needed.

The behaviors of each operator are summarized in the following list. For brevity, the numerical value of a "pixel" referred to below is the value of the corresponding channel of that pixel, while a "normalized pixel" is that number divided by the maximum installation-dependent value QuantumRange.

If normalized pixels are used, they are restored, following the other calculations, to the full range by multiplying by QuantumRange. The specified functions are applied only to each previously set -channel in the image. If necessary, the results of the calculations are truncated clipped to fit in the interval [0, QuantumRange ].

To print a complete list of -evaluate operators, use -list evaluate. AddModulus has been added as of ImageMagick 6. It is therefore equivalent to Add unless the resulting pixel value is outside the interval [0, QuantumRange ]. Exp or Exponential has been added as of ImageMagick 6. The value used with Exp should be negative so as to produce a decaying exponential function.

Non-negative values will always produce results larger unity and thus outside the interval [0, QuantumRange ]. The formula is expressed below. If the input image is squared, for example, using -function polynomial "2 0 0" , then a decaying Gaussian function will be the result.

Log has been added as of ImageMagick 6. This a scaled log function. The value used with Log provides a scaling factor that adjusts the curvature in the graph of the log function. The formula applied to a normalized value u is below. Pow has been added as of ImageMagick 6. Note that Pow is related to the -gamma operator. For example, -gamma 2 is equivalent to -evaluate pow 0.

The value used with -gamma is simply the reciprocal of the value used with Pow. Cosine and Sine was added as of IM v6. The synonyms Cos and Sin may also be used.

The value scaling of the period of the function its frequency , and thus determines the number of 'waves' that will be generated over the input color range. For example, if the value is 1, the effective period is simply the QuantumRange ; but if the value is 2, then the effective period is the half the QuantumRange.

See also the -function operator, which is a multi-value version of evaluate. Alter channel pixels by evaluating an arithmetic, relational, or logical expression over a sequence of images.

Ensure all the images in the sequence are in the same colorspace, otherwise you may get unexpected results, e. add -colorspace sRGB to your command-line. To print a complete list of -evaluate-sequence operators, use -list evaluate. No further options are processed after this option. Useful in a script to force the magick command to exit without actually closing the pipeline that it is processing options from.

You can also use the option as a final option on the magick command line instead of an implicit output image, to completely prevent any image write. Note, even the NULL: coder requires at least one image, for it to 'not write'! This option does not require any images at all. If the image is enlarged, unfilled areas are set to the background color.

To position the image, use offsets in the geometry specification or precede with a -gravity setting. To specify how to compose the image with the background, use -compose. The following command reduces or expands a JPEG image to fit on an x display.

If the aspect ratio of the input image isn't exactly , then the image is centered on an x black canvas:. The command can also be used with a ratio. If the image is not already at that ratio, it will be cropped to fit it. The -gravity setting has the expected effects. The following command crops a JPEG image so that it has a ratio:. This option is most useful for extracting a subregion of a very large raw image. Note that these two commands are equivalent:.

This setting suggests a font family that ImageMagick should try to use for rendering text. If the family can be found it is used; if not, a default font e. Note, the family can be a CSS-style font list. For other settings that affect fonts, see the options -font , -pointsize , -stretch , -style , and -weight. Display co-occurrence matrix texture measure features for each channel in the image in each of four directions horizontal, vertical, left and right diagonals for the specified distance.

This option is new as of ImageMagick 6. It transforms an image from the normal spatial domain to the frequency domain. In the frequency domain, an image is represented as a superposition of complex sinusoidal waves of varying amplitudes. The image x and y coordinates are the possible frequencies along the x and y directions, respectively, and the pixel intensity values are complex numbers that correspond to the sinusoidal wave amplitudes.

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Below is list of command-line options recognized by the ImageMagick command-line tools. If you want a description of a particular option, click on the option name in the navigation bar above and you will go right to it. Unless otherwise noted, each option is recognized by the commands: convert and mogrify.

A Gaussian operator of the given radius and standard deviation sigma is used. If sigma is not given it defaults to 1. The sigma value is the important argument, and determines the actual amount of blurring that will take place. The radius is only used to determine the size of the array which holds the calculated Gaussian distribution. It should be an integer.

If not given, or set to zero, IM will calculate the largest possible radius that will provide meaningful results for the Gaussian distribution. See Image Geometry for complete details about the geometry argument.

The -adaptive-resize option defaults to data-dependent triangulation. Use the -filter to choose a different resampling algorithm. Offsets, if present in the geometry string, are ignored, and the -gravity option has no effect. This option is enabled by default. An attempt is made to save all images of an image sequence into the given output file. However, some formats, such as JPEG and PNG, do not support more than one image per file, and in that case ImageMagick is forced to write each image as a separate file.

As such, if more than one image needs to be written, the filename given is modified by adding a -scene number before the suffix, in order to make distinct names for each image. As an example, the command. will create a sequence of 17 images the two given plus 15 more created by -morph , named: my00morph. jpg, my01morph. jpg, my02morph. In summary, ImageMagick tries to write all images to one file, but will save to multiple files, if any of the following conditions exist Set the drawing transformation matrix for combined rotating and scaling.

This option sets a transformation matrix, for use by subsequent -draw or -transform options. The matrix entries are entered as comma-separated numeric values either in quotes or without spaces. Internally, the transformation matrix has 3x3 elements, but three of them are omitted from the input because they are constant. The new transformed coordinates x' , y' of a pixel at position x , y in the original image are calculated using the following matrix equation.

The size of the resulting image is that of the smallest rectangle that contains the transformed source image. The parameters t x and t y subsequently shift the image pixels so that those that are moved out of the image area are cut off. The transformation matrix complies with the left-handed pixel coordinate system: positive x and y directions are rightward and downward, resp. If the translation coefficients t x and t y are omitted they default to 0,0.

Therefore, four parameters suffice for rotation and scaling without translation. Scaling by the factors s x and s y in the x and y directions, respectively, is accomplished with the following.

See -transform , and the -distort method ' Affineprojection for more information. Translation by a displacement t x , t y is accomplished like so:. The cumulative effect of a sequence of -affine transformations can be accomplished by instead by a single -affine operation using the matrix equal to the product of the matrices of the individual transformations.

An attempt is made to detect near-singular transformation matrices. If the matrix determinant has a sufficiently small absolute value it is rejected.

Used to set a flag on an image indicating whether or not to use existing alpha channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument type from the list below. This is a convenience for annotating an image with text. For more precise control over text annotations, use -draw. The values Xdegrees and Ydegrees control the shears applied to the text, while t x and t y are offsets that give the location of the text relative any -gravity setting and defaults to the upper left corner of the image.

Using -annotate degrees or -annotate degrees x degrees produces an unsheared rotation of the text. The direction of the rotation is positive, which means a clockwise rotation if degrees is positive. This conforms to the usual mathematical convention once it is realized that the positive y —direction is conventionally considered to be downward for images. The new transformed coordinates x' , y' of a pixel at position x , y in the image are calculated using the following matrix equation.

If t x and t y are omitted, they default to 0. This makes the bottom-left of the text becomes the upper-left corner of the image, which is probably undesirable. Adding a -gravity option in this case leads to nice results. Text is any UTF-8 encoded character sequence. If text is of the form ' mytext. txt', the text is read from the file mytext. Text in a file is taken literally; no embedded formatting characters are recognized. By default, objects e. text, lines, polygons, etc.

are antialiased when drawn. This will then reduce the number of colors added to an image to just the colors being directly drawn. That is, no mixed colors are added when drawing such objects. This option creates a single longer image, by joining all the current images in sequence top-to-bottom.

If they are not of the same width, narrower images are padded with the current -background color setting, and their position relative to each other can be controlled by the current -gravity setting. For more flexible options, including the ability to add space between images, use -smush. Use this option to supply a password for decrypting a PDF that has been encrypted using Microsoft Crypto API MSC API. The encrypting using the MSC API is not supported. For a different encryption method, see -encipher and -decipher.

This works well for real-life images with little or no extreme dark and light areas, but tend to fail for images with large amounts of bright sky or dark shadows. It also does not work well for diagrams or cartoon like images. It uses the -channel setting, including the ' sync ' flag for channel synchronization , to determine which color values is used and modified. As the default -channel setting is ' RGB,sync ', channels are modified together by the same gamma value, preserving colors.

This is a 'perfect' image normalization operator. It finds the exact minimum and maximum color values in the image and then applies a -level operator to stretch the values to the full range of values. On the other hand it is the right operator to use for color stretching gradient images being used to generate Color lookup tables, distortion maps, or other 'mathematically' defined images.

The operator is very similar to the -normalize , -contrast-stretch , and -linear-stretch operators, but without 'histogram binning' or 'clipping' problems that these operators may have. That is -auto-level is the perfect or ideal version these operators. It uses the -channel setting, including the special ' sync ' flag for channel synchronization , to determine which color values are used and modified. Adjusts an image so that its orientation is suitable for viewing i.

top-left orientation. This operator reads and resets the EXIF image profile setting 'Orientation' and then performs the appropriate 90 degree rotation on the image to orient the image, for correct viewing.

This EXIF profile setting is usually set using a gravity sensor in digital camera, however photos taken directly downward or upward may not have an appropriate value. Also images that have been orientation 'corrected' without reseting this setting, may be 'corrected' again resulting in a incorrect result.

If the EXIF profile was previously stripped, the -auto-orient operator will do nothing. The computed threshold is returned as the auto-threshold:verbose image property. This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the background color. The color is specified using the format described under the -fill option. The default background color if none is specified or found in the image is white.

Repeat the entire command for the given number of iterations and report the user-time and elapsed time. For instance, consider the following command and its output. Modify the benchmark with the -duration to run the benchmark for a fixed number of seconds and -concurrent to run the benchmark in parallel requires the OpenMP feature.

In this example, 5 iterations were completed at 2. This option shifts the output of -convolve so that positive and negative results are relative to the specified bias value.

This is important for non-HDRI compilations of ImageMagick when dealing with convolutions that contain negative as well as positive values. This is especially the case with convolutions involving high pass filters or edge detection.

Without an output bias, the negative values are clipped at zero. See the discussion on HDRI implementations of ImageMagick on the page High Dynamic-Range Images.

For more about HDRI go the ImageMagick Usage pages or this Wikipedia entry. A non-linear, edge-preserving, and noise-reducing smoothing filter for images. It replaces the intensity of each pixel with a weighted average of intensity values from nearby pixels. This weight is based on a Gaussian distribution.

We don't juggle when it comes to pricing! Facebook Twitter LinkedIn Email Copy Link. This includes the operators, -compare , -composite , -layers composite, -flatten , -mosaic , -layers merge, -border , -frame , and -extent. Robots and Auto Trading Strategy Scams Payment Methods. Replace the channel values in the first image using each corresponding channel in the second image as a c olor l ook u p t able. Assignment Essays essays are NOT intended to be forwarded as finalized work as it is only strictly meant to be used for research and study purposes. This allowed us to get the most authentic information possible.

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