roy@alanine.phri.nyu.edu (Roy Smith) (02/14/90)
Here's the scoop on my AppleScan problem. First, there's a new
version of AppleScan, 1.0.2, which you can get from your dealer. It fixes
some bugs, but it was never made clear to me if the bugs it fixed were the
ones causing my crashes. There's also a neat HyperScan stack. Second,
there's a hardware fix to old scanners (S/N < 9300249) to remove some
capacitors from the SCSI bus. They're unnecessary and sometimes cause bus
timing problems when scanning or saving large files if you have many SCSI
devices, long cables, a Quantum hard disk, and/or a fast machine (II-c[xi]).
Your dealer should do it for free; tell him it's the October 1989 repair
extension program entitled "AppleScanner Main Logic Board Upgrade".
Now, for the PostScript question. The way AppleScan (and,
apparantly, most other bitmap manipulation programs) work is to take a
greyscale image and turn it into a halftone bitmap, then send the halftone
image to the printer. Wouldn't it be better to just take the greyscale
image and send it to the printer and let the PostScript machinery do the
halftone processing? What I'm doing is proofing scanned images on my
LaserWriter, but expect to print the final copies on a high-res (2540 dpi)
machine at a service bureau. The halftones that AppleScan produces are
optimized for the LaserWriter, which seems to rather defeat the purpose.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
roy@alanine.phri.nyu.edu -OR- {att,philabs,cmcl2,rutgers,hombre}!phri!roy
"My karma ran over my dogma"jef@well.sf.ca.us (Jef Poskanzer) (02/14/90)
In the referenced message, roy@alanine.phri.nyu.edu (Roy Smith) wrote: } The way AppleScan (and, }apparantly, most other bitmap manipulation programs) work is to take a }greyscale image and turn it into a halftone bitmap, then send the halftone }image to the printer. Wouldn't it be better to just take the greyscale }image and send it to the printer and let the PostScript machinery do the }halftone processing? Yes. It's almost always better to use the grayscale scanning option in AppleScan. If you're going to send the result to a printer, then as you point out PostScript can do a better job of halftoning than AppleScan can. And even if you want a bitmap for screen display, any of the freely-available bitmap manipulation programs will also do a better job of halftoning than AppleScan. For instance, my PBMPLUS package does zig-zag Floyd-Steinberg error diffusion that makes AppleScan's dithering look sick. --- Jef Jef Poskanzer jef@well.sf.ca.us {ucbvax, apple, hplabs}!well!jef Alcohol 0% by volume.
isle@eleazar.dartmouth.edu (Ken Hancock) (02/15/90)
In article <16151@well.sf.ca.us> Jef Poskanzer <jef@well.sf.ca.us> writes: >Yes. It's almost always better to use the grayscale scanning option >in AppleScan. If you're going to send the result to a printer, then >as you point out PostScript can do a better job of halftoning than >AppleScan can. And even if you want a bitmap for screen display, >any of the freely-available bitmap manipulation programs will also >do a better job of halftoning than AppleScan. For instance, my >PBMPLUS package does zig-zag Floyd-Steinberg error diffusion that >makes AppleScan's dithering look sick. What I'd like to know is why Apple hasn't released a new version of AppleScan which allows you to print a grayscale scan to the LaserWriter -- especially since LaserWriter 6.0 has color/grayscale printing options. Ken -- Ken Hancock '90 | DISCLAIMER: I'm graduating and looking for Consultant | a job, so I'll stand by my words. Computer Resource Center |============================================== Dartmouth College | EMAIL: isle@eleazar.dartmouth.edu