CompuServe Thread

Halftone in PPage?

6 messages in this thread
#117446From: Joe LoweryOct 9, 1993 9:06 AM
What's the best way to print b&w photos for reproduction from PPage? Traditionally, you would get a velox or halftone made of a photo and drop it in, so how do I duplicate that process electronically? I notice that there is a "Halftone" radio button in the DotMatrix print requester, but, naturally, I'm printing postscript. Any words of wisdom here? Thanks – Joe
#117676From: Malcolm O'BrienOct 11, 1993 9:40 PM
Joe, What you want to do is scan the photos into an IFF file and drop them into a box in PPage. At Transactor we used to use DigiView for some illustrations. In fact, we used it to do the product package shot for DigiView and most folks would never know that it wasn't a stripped-in photo. I also used it in the 8-bit Transactor for an illustration of a circuit board. Worked well! You could read the numbers printed on the chips. I think scanning would give you better resolution than a video capture but a circuit board is tough to put in the scanner. Malcolm
#117718From: Joe LoweryOct 12, 1993 10:11 AM
Malcolm – Do you remember what lpi value you used? I'm trying to retain maximum contrast for a black & white photo. Thanks… – Joe
#117976From: Malcolm O'BrienOct 14, 1993 3:17 PM
I generally use a 133 line screen for the Lino and maybe 60 for a laser proof. I don't really know what number is best for a laser and they probably vary. I suppose that, as you go up the numbers, there's some point where higher numbers don't result in any better image, just longer output time.
#117982From: Jochen HaeberleOct 14, 1993 4:16 PM
Hi, both of you. The screen you use for a halftone picture surely defines the detail and therefore the quality of the picture you reproduce. But the resolution of the output device in combination with the screen frequency make up the possible numbers of colors reproduced. That is, postscript is able to give you 256 colors (or shades of grey to be exact). To display 256 colors, you need a matrix of 16×16. Given the resolution of your printer you could easyly calculate the biggest frequency you could use to get all colors possible. The other way round: the higher the frequency you use, the lesser colors you'll get! … over the ocean Jochen, Stuttgart, Germany with AutoPilot
#118422From: Malcolm O'BrienOct 17, 1993 2:17 AM
Jochen, Sorry, I don't follow. I need a matrix of 16×16? If my printer is 300dpi, what formula do I use to calculate the number of screen lines? Malcolm