CompuServe Thread

Post V1.86 IFF halftone?

3 messages in this thread
#180097From: Thomas H. GiebinkDec 29, 1994 11:23 AM
Help anyone?? Everything works great on my canon 4000.. beautiful print output. However I can't figure out how to get a full grey scale rendition as a saved IFF image. What I get is always B&W, 2 bit planes. I save my PS file from ProPage as an 8bit graphic, B&W page, then go to V1.86 to print it select Iff file B&W. I get 75 x 75 DPI and page size of 618 x 876 Halftone is set to 20000 as my setting. What am I missing… Advice sorely needed. Thanks very much Tom
#180241From: Arnie CachelinDec 30, 1994 12:19 PM
Postscript NEVER created grayscales in any way but halftoning, and Post doesn't do anything clever like interpreting various htone densities into gray pixels. I suspect you will have to adjust the screen density parameters in propage, and the output density/dpi parameters in post. If your printer can do 300dpi, thats pure B&W dots. to do greys, it makes larger dots, halftone cells, which have varying #s of dots on and off to acheive the appearance of a greyscale. This reduces the effective resolution of the printer: A 4×4 htone cell has 16 levels of grey, but makes a 300dpi printer into 300/4(=75) grey pixels/inch. Typically a cell will be 8×8 for 256 levels, and 300/8 effective dpi. This is why people output to 2570dpi imagesetters for printing art. You will have to adjust both the settings that PPage uses to create the halftone grays, and the settings that ost uses to send the dots to the printer, so that you get the most out of your printer. To actually answer your question, for an IFF screen with greyscales, print the thing 8times to large, then shrink it with ADPro or something that will work in 8-or 24- bits. When adpro shrinks the image, it will average the halftone cells into actual 8-bit grey pixels. I think a newer versin of post.library is around here, which actually works in 8-bit depth.. it is version 22.xx beta
#180352From: Thomas H. GiebinkDec 31, 1994 10:51 AM
Many thanks Arnie for the great description of Propage, Post, printer, IFF output. I'd never really understood the relationships before Great fortune to you this new year TOM in texas