Open Source C Image Converters

GraphicsMagick provides a set of commandline tools and programming APIs for manipulating, editing, and converting raster and vector images. It is derived from ImageMagick, with the objective of providing better stability and performance than ImageMagick while retaining the original MIT/X11 license.

A whole bunch of utilities for primitive manipulation of graphic images. Wide array of converters from one graphics format to another. E.g. from g3 fax format to jpeg. Many basic graphics editing tools such as magnifying and cropping.

Reference library for supporting the Portable Network Graphics (PNG) format.

Teem is a set of ANSI C libraries for manipulation, measurement, and visualization of structured scientific data. Includes N-dimensional image I/O and processing, volume rendering, diffusion tensor processing, ray tracing, PostScript rendering, and more.

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

GUI and command line tools for advanced users and administrators: wxdkdraw - Minimalistic drawing application for use with LaTeX, wxd2lat - Convert wxdkdraw files to LaTeX, bitmap2pp - Convert PNG/JPEG/TIFF/NetPBM to (E)PS or PDF, fig2lat - Convert XFig files to LaTeX, htmlbook - publish HTML like a book, dkcpre - C debugging and tracing preprocessor, itadmin - manage your IT using a MySQL/MariaDB database, dk-fic - file integrity checker, dk-ls - list files, output column order is configurable, dk-cat, dk-sort, dk-lines - text tools for *x and Windows, dk-send, dk-recv - transmit data stream, dk-t2h, dk-t2l - text to HTML or LaTeX conversion.

Lynkeos is a Cocoa® application dedicated to the processing of astronomical digital images taken through a telescope. It is optimized for SSE vectorized instructions sets, multi-processor and multi-core machines.

ImageMagick® is a free and open-source software suite for displaying, converting, and editing raster image and vector image files. It can read and write over 200 image file formats, and can support a wide range of image manipulation operations, such as resizing, cropping, and color correction. ImageMagick is written in C and is available for a wide range of operating systems, including Linux, macOS, and Windows. It can be used as a standalone application, or as a library that can be integrated into other software programs. Overall, ImageMagick is a powerful and versatile software suite for displaying, converting, and editing image files. Its support for scripting and automation, along with its other features, make it a valuable tool for a wide range of image-related tasks.

a medical image conversion utility & library; hereby hoping to lower at least one barrier in medical research projects.

Retro Computer Image Library decodes Amiga, Amstrad CPC, Apple II, Atari 8-bit, Atari Portfolio, Atari ST/TT/Falcon, BBC Micro, Commodore 64, Commodore 16/116/Plus4, Commodore 128, Electronika BK, FM Towns, HP 48, Macintosh 128K, MSX, NEC PC-80/88/98, Oric, SAM Coupe, Sharp X68000, Tandy 1000, Timex 2048, TRS-80, TRS-80 Color Computer, ZX81 and ZX Spectrum picture formats. The project contains a simple viewer, plug-ins for general-purpose image viewers and editors, and an everything-to-png converter.

Netpbm2Gimp automatically compiles the unmodified source code of a Netpbm graphics program into a GIMP plug-in. The result looks and functions like any other GIMP plug-in although it takes much less effort to produce than a hand-coded GIMP plug-in.

FreeImage is a library project for developers who would like to support popular graphics image formats (PNG, JPEG, TIFF, BMP and others). Some highlights are: extremely simple in use, not limited to the local PC (unique FreeImageIO) and Plugin driven!

libjpeg-turbo is a JPEG image codec that uses SIMD instructions (MMX, SSE2, NEON, AltiVec) to accelerate baseline JPEG compression and decompression on x86, x86-64, ARM, and PowerPC systems. On such systems, libjpeg-turbo is generally 2-6x as fast as libjpeg, all else being equal. On other types of systems, libjpeg-turbo can still outperform libjpeg by a significant amount, by virtue of its highly-optimized Huffman coding routines. In many cases, the performance of libjpeg-turbo rivals that of proprietary high-speed JPEG codecs. libjpeg-turbo implements both the traditional libjpeg API as well as the less powerful but more straightforward TurboJPEG API. libjpeg-turbo also features colorspace extensions that allow it to compress from/decompress to 32-bit and big-endian pixel buffers (RGBX, XBGR, etc.), as well as a full-featured Java interface.

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.

abcCairo is a project to create a Cairo backend for abcm2ps, enabling it to generate output in the formats supported by the Cairo library; PNG, SVG and PDF. abcm2ps is a command line program written by Jean-François Moine which converts abc music notation to music sheet in PostScript or SVG format. It is an extension of Michael Methfessel's abc2ps. This project takes out the PostScript commands to generate various musical symbols and instead replaces them with Cairo function calls that generate the same musical symbols. The Cairo graphics library is an open-source graphics library offering a similar 2D graphics model to PostScript. The Cairo library can write to a GTK canvas, allowing integration with programs using the GTK+ toolkit, or it can write to an image file in a choice of formats: PNG, SVG or PDF. This means that other programs can have access to the abcm2ps music-rendering capability without having to incorporate a PostScript interpreter.

The littleutils include duplicate file finders (repeats, repeats.pl, repeats.py), image optimizers (opt-jpg, opt-png, opt-gif, recomp-jpg), file rename tools (lowercase, uppercase, pren), archive recompressors (to-gzip, to-bzip2, to-bzip3, to-7zip, to-lzma, to-lzip, to-xz), a tempfile utility (tempname), file property tools (filedate, filemode, filenode, fileown, filesize, and lrealpath), and others. See the README file for more details.

Image Conversion utility to convert, compress, and decompress up to 4-bit grayscale images for displaying on the PalmPilot/III. It can take any pbm, pnm, pgm file generated by the netpbm package and convert it into a suitable image for the Pilot.

This is a console application but also has an optional GUI interface. Converts a BMP with 256 colors or less into the Sixel format. Sixel supports a maximum of 256 colors although many terminals only support 16 colors. If your BMP has more than 256 colors, or fewer colors but uses greater than 8 bits per pixel, reduce the color count using a program like IrfanView and "Decrease Color Depth". This program and its older brother PCX2SIX (circa 1995) are responsible for many of the Sixel images floating around the internet today. The original BMP2SIX program written April 2001, now is updated to compile under PellesC, and provides a GUI interface. BMP2SIX output examples can be found on SourceForge under the SixelViewer program at this location, https://sourceforge.net/projects/sixelviewer/files/Sixel_Pics/ Release date 10/31/2022 version 1.2 adding Sixel HLS as an output option

Software for manipulating Apple macOS Icon Image format (.icns) files. Provides support for reading and writing icns files in most sizes. Includes a library and three utilities for manipulating files in the .icns format: icns2png icontainer2icns icnsutil

BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.

The jbig2dec project is no longer hosted here. Please see: https://www.ghostscript.com JBIG2 is a compression format for lossless and lossy encoding of scanned monochrome documents at moderately high resolution. It is very efficient in that domain, claiming 100:1 compression. jbig2dec is a decoder-only implementation of the format.

Luminance HDR is a complete suite for HDR imaging workflow. It provides a wide range of functionalities, during both the fusion stage and the tonemapping stage. Its graphical user interface, based on Qt5, runs on a variety of platforms, such as Microsoft Windows, Mac OS X 10.9 and later and several Unix flavors (Linux, FreeBSD and others). Input images can be supplied in multiple formats, from JPEG to RAW files. In the same way, output can be saved in many different formats as well, from JPEG to TIFF (both 8 bit and 16 bit per channel), enabling all the power of your post processing tools.

png2jpeg is a simple command-line image converter from PNG to JPEG.

A small command-line tool for converting AtariST images (.neo, .pi1, .pi2, .pi3) to gifs (using gd). Please note that you may find the project "RECOIL" at SF, which supports far more formats.

libUEMF is a portable C99 implementation for reading and writing Windows Metafile, Enhanced Metafile, and Enhanced Metafile Plus (WMF, EMF, and EMF+) files. libUEMF avoids collisions with Microsoft defined functions and values, so portable programs which use it and have a Windows version do not require any conditional logic to separate the native GDI/GDI+ support from the equivalent functions provided by libUEMF. libUEMF does not implement GDI/GDI+ calls. Instead, for each metafile record type, and each object type incorporated into such a record, it provides corresponding *_set, *_get, *_print, and *_swap functions. Additional functions are provided for assembling the metafile in memory, debugging, and providing any needed byte swapping (an EMF file's internal data representation is always Little Endian.)