OpenCV has quite good performance. It should be sufficient for most cases.
To improve performance, you can also use OpenCV together with Intel IPP, which is however a non-free commercial product. If OpenCV detects that IPP is installed it will use it where possible.
As a third option you can use IPP directly. IPP was designed with high performance (on Intel architectures) as a goal. It is optimized to use the intel SIMD instructions.
Answer from Dani van der Meer on Stack Overflow Top answer 1 of 11
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OpenCV has quite good performance. It should be sufficient for most cases.
To improve performance, you can also use OpenCV together with Intel IPP, which is however a non-free commercial product. If OpenCV detects that IPP is installed it will use it where possible.
As a third option you can use IPP directly. IPP was designed with high performance (on Intel architectures) as a goal. It is optimized to use the intel SIMD instructions.
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imagemagick is quite popular.
Quora
quora.com › What-are-the-best-libraries-for-image-processing-in-C
What are the best libraries for image processing in C? - Quora
Answer (1 of 2): You asked for an image processing library in C (not C++). I assume this is by intention. You also asked for the best library. Let me first say some words about the latter. It’s only possible to assess which library is the best if the functional and preformance requirements and al...
C++ Image Processing Libraries - Stack Overflow
I am looking for a C++ library for image processing. I need the library to threshold a PPM photo (color photo). Should I write my own code? what do you guys think? More on stackoverflow.com
Real-time image processing library that isn't actually C++?
In no particular order: libvips sod zimg FFmpeg More on reddit.com
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March 15, 2020Well-documented, Open Source and Fast C/C++ image manipulation library. Like 'resize', rotate, change color, crop - Stack Overflow
Looking for a bunch of optimized image processing utility functions. Like: Resize with Cubic Interpolation, Rotate, Crop, Change a Color to a different Color. Much like what the GIMP has. But witho... More on stackoverflow.com
Image Processing in C++ and what to learn next ?
Write a program that does basic BMP image file I/O. There is a very comprehensive BMP file format spec on wikipedia complete with examples. Once you have a program that can read and write BMP files, you can save any image in the right BMP format using GIMP or similar software, and then do image processing on the contents with C++ any way you want. Then you can write the image back to a file and open it with your operating system the normal way to view the result. Simpler than OpenGL, good experience with binary file I/O, and doesn't require libraries that get in the way of understanding the low-level aspects of dealing with raw pixels. More on reddit.com
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July 10, 2021Videos
33:31
Let's do a little image processing in C - YouTube
32:30
C++ and Qt Tutorial: Image Processing Application! - YouTube
02:21:06
C Programming: Image manipulations with arrays - YouTube
14:10
Image Processing With C++ Ep.9 - Overlaying Text On Images - YouTube
37:12
C++ Image Programming From Scratch - 4.1 - YouTube
18:59
Image Processing with C++: Ep. 1 - Setup - YouTube
SourceForge
sourceforge.net › home › open source software › multimedia › graphics › image processing › image processing libraries
Best Open Source C Image Processing Libraries for Mac
With up to 25k MAUs and unlimited Okta connections, our Free Plan lets you focus on what you do best—building great apps. You asked, we delivered! Auth0 is excited to expand our Free and Paid plans to include more options so you can focus on building, deploying, and scaling applications without having to worry about your security. Auth0 now, thank yourself later. ... Fourier is a portable image processing and analysis library written in ANSI C.
Top answer 1 of 7
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Magick++ might help. It's the library version of ImageMagick.
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All of the above options should be able to do what you required.
I would like to add OpenCV to the list. It's a fast cross-platform computer vision library with extensive image loading, saving and processing support. It's written in C, but it has a solid C++ interface, which I have used in the past.
That being said: Reading / writing PPMs is straight-forward, so if all you need is to read and threshold, you should definitely consider doing it yourself. It would come down to reading the PPM bytes into memory, greyscaling by averaging the RGB color channels (note that averaging the RGB channels is one, very simple, method to greyscale; there are more), then thresholding and writing away.
SourceForge
camellia.sourceforge.net
Camellia Image Processing and Computer Vision library
Exclusive RLE (Run-Length Encoded) image processing algorithms, for faster than light image processing. Exclusive algorithms, including Hierarchical Watershed and 3DRS Motion Estimation. Exclusive optimisations, especially for morphological operations. Can be easily compiled on any 32-bits or 64-bits platform with any ANSI C compiler.
Cimg
cimg.eu
The CImg Library - C++ Template Image Processing Library
stands for Cool Image : It is easy to use, efficient and is intended to be a very pleasant toolbox to design image processing algorithms in C++. Due to its generic conception, it can cover a wide range of image processing applications. ... We have a comprehensive book, written in English, on how to use the Library to develop various image processing algorithms, from scratch (published by Taylor & Francis Group).
Medium
medium.com › imagescv › top-9-open-source-c-computer-vision-libraries-6690d860627b
Top 9 Open-Source C++ Computer Vision Libraries | by Yaniv Noema | imagescv | Medium
January 10, 2022 - VIGRA is a cross-platform C++ computer vision library for image processing and computer vision algorithms.
Epixinc
epixinc.com › products › pxipl.htm
PXIPL™ Image Processing Library
Image Processing and Analysis. Image Graphics and Printing. Image Morphology and Transforms. Subpixel Accuracy Measurements. ... Image Correlation. Image Load, Save, and Print. For use with XCLIB, SVOBJ, or 4MOBJ. C/C++ Library for 16 & 32 Bit DOS Programs.
Ermig1979
ermig1979.github.io › Simd › index.html
Simd Library
The Simd Library is a free open source image processing and machine learning library, designed for C and C++ programmers. It provides many useful high performance algorithms for image processing such as: image loading and saving, pixel format conversion, image scaling and filtration, extraction ...
GitHub
github.com › smistad › SIPL
GitHub - smistad/SIPL: The Simple Image Processing Library (SIPL) is a C++ library with the main goal of making it easy to go from an algorithm concept to pictures on the screen. · GitHub
The Simple Image Processing Library (SIPL) is a C++ library with the main goal of making it easy to go from an algorithm concept to pictures on the screen. - smistad/SIPL
Starred by 28 users
Forked by 11 users
Languages C++ 96.8% | CMake 3.2%
Quora
quora.com › What-is-a-good-C-library-to-do-basic-image-manipulation-such-as-resizing-rotation-cropping-etc
What is a good C++ library to do basic image manipulation, such as resizing, rotation, cropping, etc? - Quora
Answer (1 of 2): Hello I recommend you opencv library. I have been using it for 10+ years. It is very perfect library i have ever seen. Thanks.
Reddit
reddit.com › r/c_programming › real-time image processing library that isn't actually c++?
r/C_Programming on Reddit: Real-time image processing library that isn't actually C++?
March 15, 2020 -
I'm looking for a real-time image processing library which must be written in C for portability, but anything I search for brings only C++ up, unsurprisingly.
It cannot be written in anything else and simply use a C interface.
FileFormat
products.fileformat.com › image › imagemagick
Create, Edit, Compose & Convert Image via Open source C Image Library
1 week ago - ImageMagick stands as a premier open source library, empowering software developers to seamlessly integrate advanced image processing capabilities directly into their own C applications.
GitHub
github.com › GreycLab › CImg
GitHub - GreycLab/CImg: The CImg Library is a small and open-source C++ toolkit for image processing · GitHub
CImg defines a single image class able to represent datasets having up to 4-dimensions (from 1d scalar signals to 3d hyperspectral volumetric images), with template pixel types (bool,char,int,float,...). It also handles image collections and sequences. CImg is self-contained, thread-safe and highly portable. It fully works on different operating systems (Unix,Windows,MacOS X,*BSD,...) and is compatible with various C++ compilers (Visual C++,g++,clang++,icc,...). CImg is lightweight. It is made of a single header file CImg.h that must be included in your C++ source. It defines only four different classes, encapsulated in the namespace cimg_library.
Starred by 1.7K users
Forked by 301 users
Languages C++ 60.8% | C 31.5% | JavaScript 5.7% | HTML 1.2% | CSS 0.6% | Shell 0.1%
FileFormat
products.fileformat.com › image › libgd
C Image Processing Library – Generate & Crop, Flip or Rotate Images
October 2, 2025 - The LibGD library provides the capability to create and manipulate images with ease. It allows using the creation of images in BMP, GIF, TGA, WBMP, JPEG, PNG, TIFF, WebP, XPM file formats with just a couple of lines of C code.
University of Edinburgh
homepages.inf.ed.ac.uk › rbf › BOOKS › PHILLIPS › cips2ed.pdf pdf
Image Processing in C Second Edition Dwayne Phillips
this text may be copied without the written permission of Dwayne Phillips. If you have purchased the electronic edition of this text, you may print a ... This book is a tutorial on image processing.
Libvips
libvips.org
libvips
It comes with bindings for C, C++, and the command-line. Full bindings are available for Ruby, Python, PHP, .NET, Go, Lua, Crystal, Elixir, Java, and Nim. libvips is used as an image processing engine by Mastodon, sharp (on Node.js), imgproxy, wsrv.nl, bimg, Ruby on Rails, CarrierWave, MediaWiki, and others.
LibHunt
libhunt.com › l › c › topic › image-processing
Top 23 C Image processing Projects | LibHunt
Which are the best open-source Image processing projects in C? This list will help you: ImageMagick, libvips, chafa, sod, openexr, grass, and libgd.
Libhunt
cpp.libhunt.com › libs › image-processing
C++ Image Processing libraries | LibHunt
Video++, a C++14 high performance video and image processing library.