One of the most useful delegates I have ever created was to let me easily print images to a postscript printer. The printer was already set up using the linux "lpr" command and it could accept either a PNG format image, or a postscript file.
Here is the simple "PRT: delegate I decided to create.
Notice I decided to use postscript format ("decode="ps"") for the image being passed to the "lpr" command on my system. I chose that as I can then use options such as "-density" to adjust the size of the output image.<delegate decode="ps" encode="prt" command='lpr "%i"'/>
For example I can create a command to grab a window form my screen, modify the image, so as to fit on printed page (as I want it) then print it.
I could have also used "decode="png"", however my system would then enlarge or shrink the image to always completely fill the A4 page. You however may like this.convert x:Loopy -shave 6 -chop 0x24 -modulate 220,0 \
-bordercolor white -border 50x150 -density 130 prt:
<delegate decode="png" encode="prt" command='lpr "%i"'/>
I have added this to IM Examples (Update in a hour or two)