rrs+@andrew.cmu.edu (Robert R. Shank) (04/25/89)
The documentation I have available says the the format for storing images in files has not been defined. Can someone advise me of the status of a standard format? What are the issues? Thanks, Bob Shank send replies to rrs@cerc.wvu.wvnet.edu
raveling@venera.isi.edu (Paul Raveling) (04/27/89)
In article <cYJ9Gcy00VE60b8JAU@andrew.cmu.edu> rrs+@andrew.cmu.edu (Robert R. Shank) writes: >The documentation I have available says the the format for storing images >in files has not been defined. Can someone advise me of the status of a >standard format? What are the issues? There are probably at least a couple dozen "standard" formats. Naturally I've added my own nomination (Img format), but only after a couple years' experience with various others. My view of the main issues, approximately in order of their importance, is: 1. Complexity of software using images: The interface from application code should be as simple as possible. This in turn requires careful design to keep the software layer supporting images as simple as possible (but not simpler). 2. Disk space: Image files can consume lots if not compressed efficiently. Approximate statistics for our collection of files in compressed Img color-mapped format are: Image type Color Grayscale Monochrome Mean Img file size per image 105,400 128,300 12,679 Mean number of pixels per image 382,790 385,853 151,092 Pixels per byte 3.6 3.0 11.9 * Subset: Only checked a couple dozen monochrome images rather than all 834 in the collection. 3. Processing speed: With large amounts of data, even simple functions such as copying the data can be slow. 4. Color quantization for display: We have many raw RGB images with >200,000 unique colors, and we have displays variously capable of handling 2, 16, 64, and 256 colors. Trying to retain as much image quality when few colors are available is both necessary and challenging. Doing it fast is more challenging. 5. Associated data: Some applications need to store data of an unpredictable nature with images. ---------------- Paul Raveling Raveling@isi.edu