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.

Pngcrush optimizes PNG images. It can further losslessly compress them by as much as 40%.

libjpeg-turbo is a JPEG image codec that accelerates baseline JPEG compression and decompression using SIMD instructions: MMX on x86, SSE2 on x86-64, NEON on ARM, and AltiVec on PowerPC processors. Even on other systems, its highly-optimized Huffman coding routines allow it to outperform libjpeg by a significant amount. libjpeg-turbo implements both the traditional libjpeg API and the less powerful but more straightforward TurboJPEG API, and provides a full-featured Java interface. It supports color space extensions that allow it to compress from and decompress to 32-bit and big-endian pixel buffers (RGBX, XBGR, etc.).

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.

Gpick is an advanced color picker and palette editing tool.

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

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.

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.

WebP is a new image format that provides lossless and lossy compression for images. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller in size compared to JPEG images at equivalent SSIM index. WebP supports lossless transparency (also known as alpha channel) with just 22% additional bytes. Transparency is also supported with lossy compression and typically provides 3x smaller file sizes compared to PNG when lossy compression is acceptable for the red/green/blue color channels.

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

SNG (Scriptable Network Graphics) is a minilanguage designed specifically to represent the entire contents of a PNG (Portable Network Graphics) file in an editable form. Thus, SNGs representing elaborate graphics images and ancillary chunk data can be readily generated or modified using only text tools.

SNG is implemented by a compiler/decompiler called sng that losslessly translates between SNG and PNG.

Libtiff provides support for the Tag Image File Format (TIFF), a format used for storing image data. Included are a library, libtiff, for reading and writing TIFF and a small collection of tools for doing simple manipulations of TIFF images.

This package provides a C interface to the VIGRA C++ computer vision library. It is designed primarily to ease the implementation of higher-level language bindings to VIGRA.

IQA is a C library for objectively measuring image/video quality. It implements many popular algorithms, such as MS-SSIM, MS-SSIM*, SIMM, MSE, and PSNR. It is designed to be fast, accurate, and reliable. All code is Valgrind-clean and unit tested.

libjpeg-turbo is a JPEG image codec that accelerates baseline JPEG compression and decompression using SIMD instructions: MMX on x86, SSE2 on x86-64, NEON on ARM, and AltiVec on PowerPC processors. Even on other systems, its highly-optimized Huffman coding routines allow it to outperform libjpeg by a significant amount. libjpeg-turbo implements both the traditional libjpeg API and the less powerful but more straightforward TurboJPEG API, and provides a full-featured Java interface. It supports color space extensions that allow it to compress from and decompress to 32-bit and big-endian pixel buffers (RGBX, XBGR, etc.).

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

Leptonica is a C library and set of command-line tools for efficient image processing and image analysis operations. It supports rasterop, affine transformations, binary and grayscale morphology, rank order, and convolution, seedfill and connected components, image transformations combining changes in scale and pixel depth, and pixelwise masking, blending, enhancement, and arithmetic ops.

swappy is a command-line utility to take and edit screenshots of Wayland desktops. Works great with grim, slurp and sway. But can easily work with other screen copy tools that can output a final PNG image to stdout.

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.

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).

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.

jpegoptim provides lossless optimization (based on optimizing the Huffman tables) and "lossy" optimization based on setting maximum quality factor.

Picket is a screen color picker that includes a magnifier and supports custom formats for representing color values..

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