Batch image resize: keep transparency, ratio and fill empty space

Question

I have number of images with alpha layer, with different size and aspect ratio. I need to bring them to one size(say 150x150) with maximum possible dimensions keeping alpha and aspect ration. For example - if image is 1500x1000 - then it should be downscaled to 150x100, vertically centered and empty 25px on the top and bottom should be filled with white color. If image is 1000x1500 - then it will be downscaled to 100x150, horizontally centered and empty pixels on the left and right filled with white.

Any tools for this( win or linux)? Thanks

Answer 1

You can use ImageMagick for this sort of conversion, resizing, fill, and much more

The convert tool/command, which is a part of ImageMagick tools, supports -resize, -fill, etc options.

Below are a few links for ImageMagick commands and tutorial:

• http://www.imagemagick.org/script/command-line-tools.php
• http://www.imagemagick.org/Usage/
• http://xahlee.org/img/imagemagic.html

Answer 2

You can try:

• Graphicsmagick
• GD Library
• Imagemagick

Answer 3

Imageresize (Free, requires python)
Description:
Shrinks specified images so that the largest dimension is SIZE. Images who's largest dimension is already smaller or equal to SIZE are not touched (unless -f is given.) Images may be any format that is handled by the Python Imaging Library (PIL).