3.2.3 PPM. Portable Pix-Map Format

See the man-page.

Plain version:

• Identifier "P3"
• ASCII representation of Width
• ASCII representation of Height
• ASCII representation of Maxvalue ($<$ $65536=2^{16}$) per color component
• Height many lines of Width many pixels as 3 ASCII words 0..Maxvalue (R/G/B) separated by space

Raw version:

• Identifier "P6"
• ASCII representation of Width
• ASCII representation of Height
• ASCII representation of Maxvalue ( $<5536=2^{16}$)
• Height many lines of Width many pixels as 3 bytes or double-bytes (R/G/B) from left to right and top to bottom. The colors are coded non-linear with a gamma of 2.2.