JPEG has artifacts around text and washed colors because of lossy compression, GIF has a limited color palette (only 256 distinct colors).
Normally PNG files a bit bigger than JPEG and GIF, but with OptiPNG you can decrease the size of a PNG file quite a bit.
I have taken a screen shot of vorbis.com and saved it under different file formats:
- BMP - 2.956.854 bytes
- PNG - 130.174 bytes (IrfanView level 9 compression)
- PNG - 115.491 bytes (Microsoft Paint)
- JPEG - 99.003 bytes (80% compression)
- GIF - 90.024 bytes
- PNG - 88.040 bytes (OptiPNG on Microsoft Paint's PNG file)
- PNG - 87.967 bytes (OptiPNG on IrfanView's PNG file)
OptiPNG has been created by Cosmin Truţa, yet another famous Romanian computer science engineer