System Architecture: Intel
RedHat Release: RHL 5.2
FAQ Category: Printing and Printers
Modification Date: Feb 15, 1999
A common problem is that printers provide 300 dpi or more, however for graphics (e.g. scanned greyscale/color pictures) the maximal resolution seems to be 75 dpi, sometimes 150 dpi. How can the resolution for graphics be enhanced?
Laserprinters use a feature called dithering. They have a fixed matrix of dots, normally 75 dpi and vary the radius of these dots. So from a distance one perceives dark grey as dark grey and light grey as light grey (colour printers plot theses points of different colors over each other - like the pixels on a TV). Now if you observe the picture closely you will distinguish the points. You can even use a lineal and meassure their distance. This distance remains the same whatever you do with your printer and is by no means close to the 300 dpi you'd thought you'd get. People who use GIMP can manipulate the language their computer talks to the printer. The GIMP offers in it's print function a feature where you can choose between postscript level 1 and level 2 (what is to be recommended) or multiple other options. Best results are obtained with postscript level 2. Poscript level 3 hasn't been implemented yet. If your printer is not a postscript printer, you can find in this FAQ "Updating printtool to work with GhostScript 5.50" a hint howto use GhostScript. If you really want a photolike image you still need to send your picture to a company which has the appropiate hardware for such quality. - Until someone has an idea how to overcome this and push an ordinary laserprinter to do thatjob... However there is good news - you don't need to scan your images with more than 150 dpi. This will save you a lot of space on your harddisk...
None specified.