xzgv is a fast image viewer that provides extensive keyboard support.

PIXterm shows images directly in your terminal, recreating the pixels through a combination of ANSI character background color and the unicode lower half block element. It supports JPEG, PNG, GIF, BMP, TIFF and WebP.

Überzug is a command line util which draws images on terminals by using child windows. The advantages of using Überzug are:

• No race conditions as a new window is created to display images.

• Expose events will be processed, so images will be redrawn on switch workspaces.

• Tmux support (excluding multi pane windows).

• Terminals without the WINDOWID environment variable are supported.

• Chars are used as position - and size unit.

• No memory leak (/ unlimited cache).

Collection of graphics images created to test PNG applications like viewers, converters and editors. As far as that is possible, all formats supported by the PNG standard are represented.

libyuv is an open source project that includes YUV scaling and conversion functionality. It can:

• Scale YUV to prepare content for compression, with point, bilinear or box filter.

• Convert to YUV from webcam formats for compression.

• Convert to RGB formats for rendering/effects.

• Rotate by 90/180/270 degrees to adjust for mobile devices in portrait mode.

The JasPer Project is an initiative to provide a reference implementation of the codec specified in the JPEG-2000 Part-1 standard (i.e., ISO/IEC 15444-1).

The libUEMF library is a portable C99 implementation for reading and writing WFM, EMF, and EMF+ files.

grim can create screenshots from a Wayland compositor.

LibSIXEL is a an encoder/decoder implementation for DEC SIXEL graphics, and some converter programs. SIXEL is one of image formats for printer and terminal imaging introduced by DEC. Its data scheme is represented as a terminal-friendly escape sequence. So if you want to view a SIXEL image file, all you have to do is cat it to your terminal.

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.

This package contains a reference implementation of JPEG XL (encoder and decoder).

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.

GIFLIB is a library for reading and writing GIF images. It is API and ABI compatible with libungif which was in wide use while the LZW compression algorithm was patented. Tools are also included to convert, manipulate, compose, and analyze GIF images.

Libicns is a library for the manipulation of Mac OS IconFamily resource type files (ICNS). icns2png and png2icns are provided to convert between PNG and ICNS. icns2png will extract image files from ICNS files under names like "Foo_48x48x32.png" useful for installing for use with .desktop files. Additionally, icontainer2png is provided for extracting icontainer icon files.

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

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.

Libpng is the official PNG (Portable Network Graphics) reference library. It supports almost all PNG features and is extensible.

libimagequant is a small, portable C library for high-quality conversion of RGBA images to 8-bit indexed-color (palette) images. This library can significantly reduces file sizes and powers pngquant and other PNG optimizers.

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

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

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.

GGG (Guile Glyph Generator) is a command-line utility that allows you to generate pretty images/badges which can be used for your projects, announcing tech used, sponsoring and appreciating other projects, distinguishing versions of things supported, etc.

GGG is highly configurable, reads Scheme files where you define your tasks, and supports badges between one and three parts. It leverages SVG generation from Lisp and S-expressions, building pixel perfect badges.

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

pngcheck verifies the integrity of PNG, JNG and MNG files (by checking the internal 32-bit CRCs, a.k.a. checksums, and decompressing the image data); it can optionally dump almost all of the chunk-level information in the image in human-readable form. For example, it can be used to print the basic statistics about an image (dimensions, bit depth, etc.); to list the color and transparency info in its palette (assuming it has one); or to extract the embedded text annotations. This is a command-line program with batch capabilities (e.g. pngcheck *.png.)

Also includes pngsplit which can split a PNG, MNG or JNG file into individual, numbered chunks, and png-fix-IDAT-windowsize that allows resetting first IDAT's zlib window-size bytes and fix up CRC to match.