Removing dust spots from JPG's?

[lwhistler]

Does anyone have any ideas on removing dust spots from JPG's? Similar to using the GIMP clone tool. This is what I have in mind:

• In GIMP create mask that covers entire image, except for area next to the dust spot(s)
• Copy original image and add mask.
• Merge masked image and original image. BUT shift masked image so that unmasked areas are over dust spot.

Is there a better way? Thanks



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[fmw42]

try my isonoise script below or

1)create mask -- white where image and black where noise
2)do median filtering of whole image
3) composite the original and the median filtered version with the mask so that the mask gives back the original except where noise (black in mask) and there it uses the median filtered image.

[anthony]

The key to good 'spot' removal is how to determine the replacement colors.

You may like to look at this old article on 'text removal' which is basically the same method as what Fred describes. It looked at using morphology, and blur to determine colors,
viewtopic.php?p=41498#p41498

A similar method (using blur) is described in IM examples..
http://www.imagemagick.org/Usage/photos/#removing

A new technique, is to extract the pixels around the unwanted area and use -sparse-color to 'diffuse' just the edge pixels into the undesired parts. That is then used with the mask to replace the unwanted parts.

This example is sort of the reverse (fill inward rather than fill outward) of what you want..
http://www.imagemagick.org/Usage/canvas/#sparse_fill

Eventually I hope to make a very easy 'diffusion' method for filling 'holes' that will make this type of thing VERY easy.

[lwhistler]

Thanks for the replies, it will take me a while to study fmw42 scripts, you have a lot there. After a quick look the Zelda example - http://www.imagemagick.org/Usage/photos/#removing - looks good and I have it working in a loop on multiple images. Except I get a small black artifact in the dust spot, but so far it looks very promising.

I will post back when I have it working 100%.


Len

[anthony]

Note that JPEG is lossy. That 'dust spot' may be larger than expected, whcih would result in
a slight discolouration if your removal mask does nto cover them properly.

You can use morphology to enlarge the mask by a pixel, see if that helps!
http://www.imagemagick.org/Usage/morphology/#basic

[Bonzo]

I did try dust removal and from memory the process was:

Locate the spots and put the centers into an array

Mask all the spots with a fuzzy edge and cut out

Copy the original image and blur it than paste the imge with holes over the blured image

It worked quite well but I wanted to automate it on CR2 RAW images and IM didn't handle my RAW files very well.