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.

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

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.

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.

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.

Libiptcdata is a C library for manipulating the International Press Telecommunications Council (IPTC) metadata stored within multimedia files such as images. This metadata can include captions and keywords, often used by popular photo management applications. The library provides routines for parsing, viewing, modifying, and saving this metadata.

Libjpeg implements JPEG image encoding, decoding, and transcoding. JPEG is a standardized compression method for full-color and gray-scale images. It also includes programs that provide conversion between the JPEG format and image files in PBMPLUS PPM/PGM, GIF, BMP, and Targa file formats, as well as lossless JPEG manipulations such as rotation, scaling or cropping:

1. cjpeg

2. djpeg

3. jpegtran

4. rdjpgcom

5. wrjpgcom

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.

LodePNG is a PNG image decoder and encoder, all in one, no dependency or linkage required. It's made for C (ISO C90), and has a C++ wrapper with a more convenient interface on top.

Gpick is an advanced color picker and palette editing tool.

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.

JBIG2 is designed for lossy or lossless encoding of bilevel (1-bit monochrome) images at moderately high resolution, and in particular scanned paper documents. In this domain it is very efficient, offering compression ratios on the order of 100:1.

This is a decoder only implementation, and currently is in the alpha stage, meaning it doesn't completely work yet. However, it is maintaining parity with available encoders, so it is useful for real work.

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.

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

OpenJPEG is an implementation of JPEG 2000 codec written in C language. It has been developed in order to promote the use of JPEG 2000, a still-image compression standard from the Joint Photographic Experts Group (JPEG). Since April 2015, it is officially recognized by ISO/IEC and ITU-T as a JPEG 2000 Reference Software.

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.

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.

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

JPEG XR is an approved ISO/IEC International standard (its official designation is ISO/IEC 29199-2). This library is an implementation of that standard.

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

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.

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.

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.

ImageMagick is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 100) including DPX, EXR, GIF, JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF. Use ImageMagick to resize, flip, mirror, rotate, distort, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves.