ImageWorsener is a cross-platform command-line utility and library for image scaling and other image processing. It has full support for PNG, JPEG, and WebP files, read-only support for GIF files, and limited support for some other image formats. It’s not as fast or memory-efficient as some utilities, but it’s very accurate.

It is free software, licensed under the GNU GPL v3.

The current version is 0.9.8, released 18 Feb 2012.

• Documentation
• Technical notes

Demonstrations:

• Part 1: Reducing image size, blur, grayscale, posterize, dither, etc.
• Part 2: Increasing image size, resampling filters, transparency, backgrounds, etc.

Downloads:

• 32-bit Windows binary: imageworsener-win32-0.9.8.zip
• 64-bit (x64) Windows binary: imageworsener-win64-0.9.8.zip
• Source code: imageworsener-src-0.9.8.tar.gz. The source is also available at GitHub.

Topics related to ImageWorsener and image processing (a.k.a. Things I wish I’d known better when I started this):

• Basics of image resampling
• “Bicubic resampling”
• Gamma correctness
• Converting to grayscale
• Clamping intermediate pixels
• Resizing images with transparency
• Sample quantization
• Match centers vs. match edges
• Subpixel rendering
• Filters and fairness
• A close look at the sRGB formula
• Slow power computation by 64-bit glibc

Contact: Jason Summers