OptiPNG

When it comes to saving screen shots, PNG is the number one image format due to its lossless compression.

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