PerceptualDiff visually compares two images to determine whether they look alike. It uses a computational model of the human visual system to detect similarities. This allows it too see beyond irrelevant differences in file encoding, image quality, and other small variations.

This is a tiny, header-only C++ library for manipulating INI files.

Jp2a is a small utility that converts JPEG images to ASCII.

Nifti_clib is a set of I/O libraries for reading and writing files in the nifti-1, nifti-2, and (to some degree) cifti file formats. These are binary file formats for storing medical image data, e.g. MRI and fMRI brain images.

Converseen is an image batch conversion tool. You can resize and convert images in more than 100 different formats.

libungif is the old GIF decompression library by the GIFLIB project.

Imlib2 is a library that does image file loading and saving as well as rendering, manipulation, arbitrary polygon support, etc.

It does ALL of these operations FAST. Imlib2 also tries to be highly intelligent about doing them, so writing naive programs can be done easily, without sacrificing speed.

This is a complete rewrite over the Imlib 1.x series. The architecture is more modular, simple, and flexible.

pngquant is a PNG compressor that significantly reduces file sizes by converting images to a more efficient 8-bit PNG format with alpha channel (often 60-80% smaller than 24/32-bit PNG files). Compressed images are fully standards-compliant and are supported by all web browsers and operating systems.

Features:

1. High-quality palette generation using a combination of vector quantization algorithms.

2. Unique adaptive dithering algorithm that adds less noise to images than the standard Floyd-Steinberg.

3. Easy to integrate with shell scripts, GUIs and server-side software.

4. Fast mode for real-time processing/large numbers of images.

JBIG-KIT implements the JBIG1 data compression standard (ITU-T T.82 and ISO/IEC 11544:1993), designed for bi-level (one bit per pixel) images such as black-and-white scanned documents. It is widely used in fax products, printer firmware and drivers, document management systems, and imaging software.

This package provides a static C library of (de)compression functions and some simple command-line converters similar to those provided by netpbm.

Two JBIG1 variants are available. One (jbig.c) implements nearly all options of the standard but has to keep the full uncompressed image in memory. The other (jbig85.c) implements just the ITU-T T.85 profile, with memory management optimized for embedded and fax applications. It buffers only a few lines of the uncompressed image in memory and is able to stream images of initially unknown height.

grim can create screenshots from a Wayland compositor.

APNG (Animated Portable Network Graphics) is an unofficial extension of the APNG (Portable Network Graphics) format. APNG patch provides APNG support to libpng.

Gifsicle is a command-line GIF image manipulation tool that:

• Provides a batch mode for changing GIFs in place.

• Prints detailed information about GIFs, including comments.

• Control over interlacing, comments, looping, transparency, etc.

• Creates well-behaved GIFs: removes redundant colors, only uses local color tables, etc.

• Shrinks colormaps and change images to use the Web-safe palette.

• Optimizes GIF animations, or unoptimizes them for easier editing.

Two other programs are included with Gifsicle: gifview is a lightweight animated-GIF viewer, and gifdiff compares two GIFs for identical visual appearance.

imgp is a command line image resizer and rotator for JPEG and PNG images. It can resize (or thumbnail) and rotate thousands of images in a go while saving significantly on storage.

This package may optionally be built with python-pillow-simd in place of python-pillow for SIMD parallelism.

Zimg implements the commonly required image processing basics of scaling, colorspace conversion, and depth conversion. A simple API enables conversion between any supported formats to operate with minimal knowledge from the programmer.

Developer's Image Library (DevIL) is a library to develop applications with support for many types of images. DevIL can load, save, convert, manipulate, filter and display a wide variety of image formats.

Libmng is the MNG (Multiple-image Network Graphics) reference library.

libspng is a simple C library for loading Portable Network Graphics (PNGs), intended as an easy-to-use replacement for libpng.

Phockup is a media sorting tool that uses creation date and time information in photos and videos to organize them into folders by year, month and day. All files which are not images or videos or those which do not have creation date information will be placed in a folder called unknown.

Gpick is an advanced color picker and palette editing tool.

MyPaint is a simple drawing and painting program that works well with Wacom-style graphics tablets.

libheif is an ISO/IEC 23008-12:2017 HEIF and AVIF (AV1 Image File Format) file format decoder and encoder.

Exiv2 is a C++ library and a command line utility to manage image metadata. It provides fast and easy read and write access to the Exif, IPTC and XMP metadata of images in various formats.

OptiPNG is a PNG optimizer that recompresses image files to a smaller size, without losing any information. This program also converts external formats (BMP, GIF, PNM and TIFF) to optimized PNG, and performs PNG integrity checks and corrections.

Mtpaint is a graphic editing program which uses the GTK+ toolkit. It can create and edit indexed palette or 24bit RGB images, offers basic painting and palette manipulation tools. It also handles JPEG, JPEG2000, GIF, TIFF, WEBP, BMP, PNG, XPM formats.