Tracy Lincoln’s post comparing Portable Network Graphics, PNG image format and other image outputs from AutoCAD is a good reference and another reminder not to assume JPEG is the best format for every image.
It’s great for photos but where there are large areas of plain colours or a limited palette often other formats like PNG can be much more efficient and give better results. I posted about this some time back when someone asked why I’d sent a PNG format screen shot rather than JPEG. I did some comparison tests with Corel PhotoPaint and a small screen-shot and the results were remarkable. PNG was much smaller and it’s lossless nature resulted in better appearance than JPEG.
Tracy has a similar comparison with AutoCAD’s image export commands.
“I remembered that I could simply send them a simple graphics file... but which format would work best?
- My test TIF was 5,354 (HUGE!!!)*
- My test BMP was 4,013KB (a large file)
- My test JPG was 386KB (more reasonable)
- My test PNG was 58KB (most excellent)!
Experimenting with image formats for screen-shots - RobiNZ CAD Blog July 28, 2006
Using Corel PhotoPaint’s export to web to a variety of formats, with the same source, then comparing the results is interesting. The file sizes range from 1.5 to 25 KB and the largest (JPG) looks nearly as good as the smallest (PNG)!* RC Comment: I suspect the TIF could be much smaller with image compression but then becomes dependent on the viewer having the same TIF format/compression capability. Not always a sure thing in my experience.
