Pixel adjustment

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peter.hansen@epfl.ch
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Joined: 2017-09-14T09:10:15-07:00
Authentication code: 1151

Pixel adjustment

Post by peter.hansen@epfl.ch » 2017-09-14T09:21:57-07:00

Hello

New user hoping to learn some tricks.
I would like to adjust pixel-values of .JPG's by applying a equation to the images.
Basically I would like to correct for pixel-value drop-off in fisheye image (correct for vignetting).
The images are to be merged with hdrgen afterwards into luminance maps - but I would like to correct for vignetting.

Can I use Imagemagick for this?
And how should I do it?

Hope to hear from you all

Kind regards
Peter

snibgo
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Joined: 2010-01-23T23:01:33-07:00
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Location: England, UK

Re: Pixel adjustment

Post by snibgo » 2017-09-14T09:48:37-07:00

Yes, IM can do this.

The easy but slow method is to use "-fx". See http://www.imagemagick.org/script/fx.php

If you have lots of images, the same size and needing the same adjustment, you can create a mask image that is composited with each of the inputs in turn for the required adjustment. This is more difficult initially, but is then much faster per image.
snibgo's IM pages: im.snibgo.com

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fmw42
Posts: 22079
Joined: 2007-07-02T17:14:51-07:00
Location: Sunnyvale, California, USA

Re: Pixel adjustment

Post by fmw42 » 2017-09-14T10:49:26-07:00

In the future when asking questions about Imagemagick, if you start using it, please see the following:

Please, always provide your IM version and platform when asking questions, since syntax may differ. Also provide your exact command line and if possible your images.

See the top-most post in this forum "IMPORTANT: Please Read This FIRST Before Posting" at viewtopic.php?f=1&t=9620

For novices, see

viewtopic.php?f=1&t=9620
http://http://www.imagemagick.org/scrip ... essing.php
http://www.imagemagick.org/Usage/reference.html
http://www.imagemagick.org/Usage/

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