[net.micro.mac] Bitmap problems w/LaserWriter

dtt@unirot.UUCP (David Temkin) (08/20/86)

Yesterday I used Thunderscan to digitize a photo at 400% enlargement.
The resulting bitmap occupies about 3.5 x 2.75 regular-sized pages.
The document (without the halftone info) occupies about 315k.  I wanted
take this picture and print it at twice this size (so that each pixel
will occupy the space of four pixels when printed - a poster-sized
picture).  Here's where the fun begins.

I had access to a LaserWriter, so I decided the easiest way to do
this would be to load the document into Thunderscan and change the
reduction/enlargement to 192% (I'd been told that this would give
exactly 8x8 Laserwriter pixels for every pixel in the bitmap) on the
Page Setup box.  I did this.  Then I printed it (LaserWriter 3.0,
Thunderscan 3.1) and, much to my surprise, the program thought it was
done printing when only one page had been printed (that's one out of 28).
It did print that page correctly, but I couldn't get it to print any
other pages.

The next thing I thought to do would be to cut the whole thing and
paste it to MacDraw. Unfortunately, it would only let me cut very
small pieces at a time, so I had to put them into the scrapbook and
move them from there. (There's a bug in Thunderscan when it comes
to cutting beyond a certain point in a big file -- it would crash the
system. I got around this by using Cmd-Shift-3 and cutting out of
smaller MacPaint documents). Anyway, I finally got the whole thing
into MacDraw. It was perfectly aligned on the screen. I changed the
reduction/enlargement to 192% (as before) and told it to print.

It did it (taking over 2 hours!), but there were a number of
problems.  The image was full of thin horizontal white lines, and
some of the pasted pieces were misaligned, even though they looked OK
on the screen. Is this a MacDraw problem (v 1.7)? Why does it divide
pasted bitmaps into separate objects? Is there a way around it?

Is there some other program I can use to cut or copy the whole Thunderscan
bitmap at once? It's too big for MacPaint or MacBillboard. There must be a
decent bitmap editor that handles documents bigger than a page.

By the way, MacDraw refused to print it on the Imagewriter. After
spinning the drive a bit, it said "The print command was not
completed". And something even stranger: the MacDraw file was 50%
LARGER than the Thunderscan file. Why? Also, is there a way to
restore a stretched bitmap to its original dimensions in MacDraw
(outside of Undo or Revert -- it's already saved)?

Could someone shed some light on this?

kearns@garfield.columbia.edu (Steve Kearns) (08/21/86)

Macdraw splits up bitmaps into pieces because there is a programming
guideline that says that no bitmap should be > 3K.  It has something
to do with stack space usage while drawing Pictures.  

The many lines come from the smoothing algorithm the Laserwriteer uses
on bitmaps.  I heard that the later versions of the Laserwriter driver
fixes this.  

-steve

briand@tekig4.UUCP (Brian Diehm) (08/23/86)

>By the way, MacDraw refused to print it on the Imagewriter. After
>spinning the drive a bit, it said "The print command was not
>completed".

MacDraw does this when it runs out of print driver buffer space on the disk it
is using for a print buffer.  The message displayed just has to be one of the
all-time informative error messages, right up there with "syntax error."

-Brian Diehm
Tektronix, Inc.