The application I am writing depends on relatively consistent output from the resample function. I need to be able to, as portably as possible. resize. -resize x+20+30 (like the -scale and -sample examples below) converts an input to an output image which has the pixel dimensions of x Hello, I am trying to reduce the resolution of images to 72×72 using convert – resample 72×72 when I do this the image size does get reduced.

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Use gamma correction to adjust for this color difference. The following answer shows a few illustrated! Using color correction on a low-quality Q8 version of IM see Quality is not recommended due to the loss of precision such a low memory quality provides. However, other clients may go technicolor when inagemagick image colormap is installed.

The initial affine matrix is eesample affected; that matrix is only changed by the appearance of another —affine option. Partition is like plane except imagemabick different planes are saved to individual files e. Use this option to affect the the color management operation of an image see —profile.

If a clipping path is present, it will be applied to subsequent operations. It is also why it produced a better result along the diagonal bottom edge of the enlarged rose image above. This option is like —page but acts as an image operator rather than a setting. Produces an effect similar to that of ‘difference’, but appears as lower contrast. The default is quality is 75, which means nearly the best compression with adaptive filtering.

This imagemayick can account for these differences. Stack Overflow works best with JavaScript enabled.

When minifying, it changes the image size simply by replacing pixel colors by averaging the respective input pixel colors together. The actual number of colors in the image may be less than your request, but never more.


Of course for most people, the normal default options is good enough as they were designed with general use in mind.


This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. Painting with white produces no change. If value is missing for a definition, rezample empty-valued definition of a flag will be created with that name. If the x is negative, the offset is measured leftward from the right edge of the screen to the right edge of the image being displayed.

Refer to quantize for a description of these values. Each image in imafemagick range is read with the filename followed by a period. If —colors is also specified, the total unique colors in the image and color reduction error values are printed.

Offsets, if present in the geometry string, are ignored, and the —gravity option has no effect. Neither the source nor the destination are used as input. When converting to PostScriptuse this option to specify a header string to print above the image. See —geometry for details about the geometry specification. Darkens or lightens the colors, dependent on the source color value. By default the color must be exact.

A negative image index counts images from the end of the current image sequence, therefore u[-1] refers to the last image in the sequence. The replace method recolors any pixel that matches the color of the target pixel.

Problems with resampling to change resolution – ImageMagick

Usage questions are like “How do I use ImageMagick to create drop shadows? Specify a range of images with a dash e. However there are reports of some version where this may have been the bottom-right, or it may have even been slightly variable due to bugs.

For example, if you want to automatically trim the edges of an image reasmple —trim but the image was scanned and the target background color may differ by a small amount.


This option enhances the intensity differences between the lighter and darker elements of the image. Width and height give the number of columns and rows to remove, and x and y are offsets that give the location of the leftmost column and topmost row to remove.

The default filter is automatically selected to provide the best quality while consuming a reasonable amount of time. When used with the mogrify utility, this option will convert any image to the image format you specify.

Segment imagemmagick image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. Selects the lighter of the destination and source colors. This imagemagcik is used with convert for obtaining image or font from this X server.

Follow the text coordinates with a string. ImageMagick Examples Preface and Index. It also completely ignores any current -filter setting. Multiplies or screens the colors, dependent on the destination color. If the XML library is not present, the option is ignored.

First of all, thank you for the highly informative answer. Perhaps someone else who is more experienced with -resample can comment. If the green or blue value is omitted, these channels use the same value as the resmple one provided. For example, if you type the following command: Amount defines the size of the neighborhood around each pixel to choose a candidate pixel to swap. If they are not of the same width, any narrow images will be expanded to fit using the background color.

If the color profile is not wanted then ” -strip ” all profiles.