Subsequently shift the image pixels so that those that are moved out of the The size of the resulting image is that of the smallest rectangle thatĬontains the transformed source image. Image are calculated using the following matrix equation. Internally, the transformation matrix has 3x3 elements, but three of themĪre omitted from the input because they are constant. The matrix entries are entered as comma-separated numeric values either in This option sets a transformation matrix, for use by subsequent -draw or -transform options. Set the drawing transformation matrix for combined rotating and scaling. a printf() integer format string (eg: "%d") is present in the output.the output image's file format does not allow multi-image files,. Save to multiple files, if any of the following conditions exist. In summary, ImageMagick tries to write all images to one file, but will morph), named: my00morph.jpg, my01morph.jpg, Will create a sequence of 17 images (the two given plus 15 more created by As anĮxample, the command magick logo: rose: -morph 15 my%02dmorph.jpg Who have used the standard printf()' C-library function. Strings, such as ' %d' or ' %03d', are familiar to those Where the -scene number is placed in the filenames. Including a C-style integer format string in the output filename willĪutomagically enable +adjoin and are used to specify Separate files, whether or not the file format allows multiple images per file Use +adjoin to force each image to be written to More than one image needs to be written, the filename given is modified byĪdding a -scene number before the suffix, in order to ImageMagick is forced to write each image as a separate file. JPEG and PNG, do not support more than one image per file, and in that case An attempt is made to save all images ofĪn image sequence into the given output file. Join images into a single multi-image file. Unless otherwise noted, each option is recognized by the commands: convert and mogrify. 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. The reference says this is more efficient and is the preferred method.Below is list of command-line options recognized by the ImageMagick command-line tools. We do not need the -alpha off mentioned in the reference, since JPG does not support any alpha channel. The result is the same as -background white -flatten. So starting with the original PNG, we do convert google.png -background white -alpha remove google_alpharemoveoff.jpg convert google_bg_white.png -flatten google_bg_white_flatten.jpgĪn alternate method to -flatten is to use -alpha remove, which is discussed. So one still needs to flatten the result, so that the antialiasing of the alpha channel will smoothly blend the colors near the boundaries. convert google_bg_white.png google_bg_white.jpg You have a nice clean background, but the image is still aliased (as it was in the original when the alpha channel was remove). However, if you simply remove the alpha channel the JPG will show aliasing since only the fully transparent pixels' background colors were changed to white. convert google.png -background white -alpha background google_bg_white.png It will look the very same as the original PNG. Often one will reprocess the original transparent PNG image so that it has some constant color underneath the alpha channel so that later one can remove the alpha channel and not have odd colors showing. Simple Flatten (default background is white): convert google.png -flatten google_flatten.jpgįlatten with black background: convert google.png -background black -flatten google_flatten_black.jpg The stripes are from the underneath color below the alpha channel.Īlpha Channel (nicely antialiased): convert google.png -alpha extract google_alpha.jpg Turn alpha off: convert google.png -alpha off google_aoff.jpg However, the background color you use will change the appearance in transparent areas from that of the underneath color. I know of no significant issues using -background xx -flatten when converting PNG or GIF to JPG. PNG allows 8-bit transparency (partial transparent). GIF only allows binary transparency - fully transparent or fully opaque. But you should specify -background somecolor before -flatten, if you do not want the default background color. So you should use -flatten to properly do that conversion. JPG does not allow transparency and any transparent areas will show what color is underneath the transparency, which is often black. The problem with converting PNG to JPG is when the PNG has transparency.
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