Scaling bitmaps

Subject: Scaling bitmaps
From: Bill Konrad <konrad -at- SAGE -dot- CC -dot- PURDUE -dot- EDU>
Date: Tue, 12 Sep 1995 17:45:20 -0500

kwatkins -at- QPI -dot- USA -dot- COM wrote:

<<The software documentation I've been creating lately contains lots of screen
shots: bitmap captures of various windows in Windows. When I need to show
the whole window in the paper docs, I can easily scale down the graphic in
Word. However,* I have found no way to scale the images when I need the
same screen shots in the on-line Help. (Well, I can "scale down" the bitmap
in any of several bitmap editors, but the text in the screen shot becomes
illegible almost instantly.) Those full-size screen shots take up an awful
lot of screen real estate.>>

I also develop Windows help and know of two solutions (there may be more,
of course). I believe both work on similar principles, though I've only
used Paint Shop Pro.

Wextech Systems (the developers of Doc-to-Help) offer a utility called
SmoothScaling which allows you to rescale bitmaps without the dreaded

Then there is the shareware utility Paint Shop Pro (PSP). This utility is
pretty remarkable (IMHO). It allows you to manipulate images in quite a
number of ways besides rescaling. However, it is not entirely intuitive how
to rescale an image smoothly in PSP. There is a command called "Resize"
which would produce the same ugly jaggies as other methods of resizing.
Don't choose the obvious.

First you need to increase the number of colors to millions. Then select
the command "Resample." This resizes the images. Finally, you want to
reduce the number of colors back down to either 16 or 256 (an image with
millions of colors can be megabytes in size).

From the printed images I've seen of SmoothScaling and from what I've seen
working with PSP, both yield acceptable results. The images do tend to
become slighty blurry. However, most detail is still recognizable and looks
much better than a resized image with the jaggies.

You can contact WexTech at 1-800-WEXTECH or 212-949-9595, or send a fax to

PSP is available at any respectable Windows archive.

Hope this helps.

Bill Konrad
konrad -at- sage -dot- cc -dot- purdue -dot- edu

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