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.

Giblib is a simple library which wraps imlib2's context API, avoiding all the context_get/set calls, adds fontstyles to the truetype renderer and supplies a generic doubly-linked list and some string functions.

FreeImage is a library for developers who would like to support popular graphics image formats like PNG, BMP, JPEG, TIFF and others.

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.

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.

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.

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

Steghide is a program to `hide' data in various kinds of image and audio files. This practice is known as steganography, but the method used by steghide is not very secure and should not be used where security is at stake. Even if a password is used, steghide offers little plausible deniability.

Nonetheless, neither color nor sample frequencies are changed, making the embedding resistant against first-order statistical tests not aimed specifically at this tool.

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.

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.

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 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

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.

Slurp can select a region in a Wayland compositor and print it to the standard output. It works well together with grim.

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

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.).

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.

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

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

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.

A pretty small png library. Currently all documentation resides in pnglite.h.

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.

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

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