Standard test image
A standard test image is a digital image file used across different institutions to test image processing and image compression algorithms. By using the same standard test images, different labs are able to compare results, both visually and quantitatively.
The images are in many cases chosen to represent natural or typical images that a class of processing techniques would need to deal with. Other test images are chosen because they present a range of challenges to image reconstruction algorithms, such as the reproduction of fine detail and textures, sharp transitions and edges, and uniform regions.
Test images as transmission system calibration material probably date back to the original Paris to Lyon fax link. Analogue Fax equipment (and photographic equipment for the printing trade) were the largest user groups of the standardized image for calibration technology until the coming of television and digital image transmission systems.
Common test images
The standard size of the images are usually 512×512 or 720×576. Most of these images are available as TIFF files from the University of Southern California's Signal and Image Processing Institute. Kodak has released a set of 24 768×512 images, available as PNGs, that are widely used for comparing image compression techniques.
- The USC-SIPI Image Database — A large collection of standard test images
- Computer Vision website — A large collection of links to various test images
- A Few Test Images — Collection of various test images
- Vision @ Reading — University of Reading's set of popular test images
- CIPR still images — Some sets of test images at Rensselaer Polytechnic Institute (including the Kodak set)
- True-color Kodak test images — The Kodak set in PNG format
- Compression Database — The superset of all available (as well as taken down) corpora used for image compression, segmentation and classification, contains most of the images of the mentioned standard corpora with detailed information about relevant quantities (entropy, statistics, etc.)
- TESTIMAGES — Huge and free collection of sample images designed for analysis and quality assessment of different kinds of displays (i.e. monitors, televisions and digital cinema projectors) and image processing tecnhiques. The archive includes more than 2 million images originally acquired and divided in three different categories: SAMPLING (aimed at testing resampling algorithms), COLOR (aimed at testing color rendering on different displays) and PATTERNS (aimed at testing the rendering of standard geometrical patterns).