Nonlinear compression in CS2

AT
Posted By
Andrey Tarasevich
Jul 2, 2005
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449
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3
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Hello

This must be a simple quiestion… I have a group portrait which is noticeably distorted in the following fashion: the left-hand side of the image is stretched along the horizontal axis (i.e. people on the left look more "fat" than they really are), the center is also stretched, but not that much, and the right-hand side of the image looks OK. In order to correct the problem I need to perform a nonlinear compression of the original image along the horizontal axis, i.e. I have to compress the left-hand side, and the amount of compression should gradually decrease as I move from left to right. What is the right tool to do this job in Photoshop CS2? I mean, I don’t mind specifying the compression amounts manually (like moving grid lines or something) since this is not exact science anyway, but I still don’t know which tool in PS (if any) is intended to perform a nonlinear shrink/stretch along only one axis.

Best regards,
Andrey

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J
johnboy
Jul 2, 2005
"Andrey Tarasevich" wrote in message
Hello

This must be a simple quiestion… I have a group portrait which is noticeably distorted in the following fashion: the left-hand side of the image is stretched along the horizontal axis (i.e. people on the left look more "fat" than they really are), the center is also stretched, but not that much, and the right-hand side of the image looks OK. In order to correct the problem I need to perform a nonlinear compression of the original image along the horizontal axis, i.e. I have to compress the left-hand side, and the amount of compression should gradually decrease as I move from left to right. What is the right tool to do this job in Photoshop CS2?

Warp.
GH
Gernot Hoffmann
Jul 2, 2005
Andrey,

I would try a perspective transform. Please read the help text.

That’s starting in PhS 7 by Crop (rather strange, IMO).
Make a rectangular cropping window and adjust the corners. Then pick the border lines at the MIDDLE and draw them outside of the used area, in order to transform the whole image. Needs some exercise.
Finally apply rectangular cropping (not perspective), in order to define the usable part of the image.

It’s probably not warping because lens systems don’t make people fat on one side of the image and slim on the other.

Best regards –Gernot Hoffmann
ME
Mike Engles
Jul 4, 2005
Andrey Tarasevich wrote:
Hello

This must be a simple quiestion… I have a group portrait which is noticeably distorted in the following fashion: the left-hand side of the image is stretched along the horizontal axis (i.e. people on the left look more "fat" than they really are), the center is also stretched, but not that much, and the right-hand side of the image looks OK. In order to correct the problem I need to perform a nonlinear compression of the original image along the horizontal axis, i.e. I have to compress the left-hand side, and the amount of compression should gradually decrease as I move from left to right. What is the right tool to do this job in Photoshop CS2? I mean, I don’t mind specifying the compression amounts manually (like moving grid lines or something) since this is not exact science anyway, but I still don’t know which tool in PS (if any) is intended to perform a nonlinear shrink/stretch along only one axis.

Best regards,
Andrey

Hello

You could do it with a displacement map.
Takes a bit of working out, but can be done.
You will need a grayscale horizontal gradient midtone to darker gray. Areas of midtone will not be displaced, but the progressively darker tones will be displaced, proportionately.
Experiment with the Displace Filter.
The demo is -100 horizontal and 0 vertical

http://www.btinternet.com/~mike.engles/mike/displace.jpg

Mike Engles

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