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need higher quality stretchblt (downsizing)

Posted on 2006-05-12
Medium Priority
Last Modified: 2010-05-18
I have a bunch of 1000x1000 grayscale images, and I display thumbnails of them by using StretchBlt, setting the mode to HALFTONE. While you can tell what the thumbnails are of, they have, well, sort of a "denim" (yeah, like your jeans) quality/texture look to them which I've been told "is not good enough"

ha! so anyway, I've tried some of the other stretchblt modes and none of them make good looking images (I'm taking them from 1000x1000 down to about 85x85, and even smaller as the number of thumbnails I have to display in the given area increases)

Can somebody recommend an alternative to stretchblt that will give me quality thumbnails?

Question by:PMH4514
  • 3
LVL 22

Accepted Solution

grg99 earned 500 total points
ID: 16669494
You need the function DWIWNWCBDBAC(), sometimes known as "Do What I Want, Not What Can BE Done By A Computer".

You're asking a computer to shrink a picture by a factor of 125, but keep the important details.
I suspect that falls into the category of "hard AI".  I'm not sure you could give arbitrary images to,
say a Leo DaVinci and get him to be generate a thumbnail that is "good".

That said, you can eliminate the "jaggies" by filtering the image with a low-pass filter.
Try some of the "demoire" options in your favorite graphics program and see if that helps.
Note that this will smooth things out, making it look a bit better, but the resolution will still be fuzzy compared to the original.

Author Comment

ID: 16669564
hah! I get DWIWNWCBDBAC requests daily :)

I can't use graphics editors, I have to do this with code as the user captures images.  problem is, the folks making those requests are aware of what Photoshop and such can do for them off-line. "It's just code right??"


Author Comment

ID: 16669704

Author Comment

ID: 16669774
well, that codegury article solved my question, but your response made me laugh so I'm going to give you the points :)

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