Netpbm Official Docs

http://netpbm.sourceforge.net/doc/

Image Type Descriptions

pbm

Black and white image format

pgm

Grayscale image format

ppm

RGB image format

pnm

Any file of the above formats

pam

Generic two-dimensional grid format

Formats are downwards compatible. For example, any ppm program can deal with pbm image, etc. Pam is downward compatible with any format.

Create thumbnails of a folder of images sized at 50%

ls *.jpg | while read item; do jpegtopnm "$item" | pamscale .50 | pnmtojpeg > `echo file | sed 's|\(.*\)\.jpg|\1-thumb.jpg|'`

Add Drop Shawdow to an Image

jpegtopnm file | pnmmargin -white 10 | ppmshadow | pnmtojpeg > file.done; mv file.done file

Label Images

jpegtopnm file | ppmlabel -text 'hi there!' | pnmtojpeg > `echo file | sed 's|\(.*\)\.jpg|\1-label.jpg|'`

Glue Images Together

images2text

   images/totakeke1.gif converted to ascii text with netpbm 
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                    M         MMMMMMMMMMMMMMMMMMo
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