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Blur level dependent on pixel position?

Posted: 2016-09-05T09:36:54-07:00
by yarr
Hello

I need to stretch oval shapes on cartographic bitmaps like this one -
Image -
in order to avoid distortions while wrapping images on sphere.

Shapes should be stretched horizontally (suppose according to log function):
maximum distortion on the top and the bottom,
minimum in the middle, like on this example:
Image

or on this one:
Image
Three frames of the same sky map area - shapes on the middle one
should be distorted like these on the right and the left image.

Is there any way to do this job with help of IM?
I guess 'blur' would be suitable tool but of course I'm not sure about that
and I don't know how to tell IM what I need to have been made.
I will be grateful for any help or references.

Forgive me my rough English please.

Best -

yarr

Re: Blur level dependent on pixel position?

Posted: 2016-09-05T09:54:12-07:00
by snibgo
You can do this with "-compose Blur". Some examples at http://im.snibgo.com/selblur.htm#xyrad

Re: Blur level dependent on pixel position?

Posted: 2016-09-05T13:02:34-07:00
by yarr
Thank you.