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showkey
Asked: 2018-10-01 23:25:33 +0800 CST

How to resize a gif without deforming and remove the blank white region when it's cropped?

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The below gif's dimensions are 600*800. Height is 800 pixels, so there's a lot of blank space at the bottom I want to remove.

source gif: old.gif

This was saved as old.gif:

file old.gif 
old.gif: GIF image data, version 89a, 600 x 800

Resized with convert command:

convert old.gif -coalesce temp.gif
convert -size 600x800 temp.gif -resize 600x400! new.gif

！ means ignore aspect ratio, do not keep aspect ratio unchanged.
Here's the result:

squashed gif

The new file new.gif is deformed.

How can I resize the gif without deforming it?

My try with -crop argument.

convert old.gif -crop 600x400+0+0 new.gif

cropped gif with whitespace

How to remove the blank region in new.gif?

The blank white region is obvious in firefox. convert old.gif -crop 600x400+0+0 new.gif can't remove the blank white region in new.gif.

gif in browser

Using the repage argument will remove the blank white region, but it makes the gif more blurred.

convert old.gif -crop 600x400+0+0 -trim  +repage  new.gif

blurry gif

command-line image-processing convert imagemagick gif

1 Answers

  1. Best Answer

    Use ! after the resolution given to -crop:

    convert old.gif -crop 600x400+0+0\! new.gif

    enter image description here

    From the imagemagick docs:

    From ImageMagick version 6.2.4-5, you can add a new special flag to the "-crop" argument. This flag '!' will tell crop to adjust the Virtual Canvas information of the returned image so that it is relative to the area cropped.

    ...

    Notice how the canvas size of the image returned now matches the area in which the image was cropped.

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