Hi anonymous,
one possibility with the current image; I'm not sure whether this would work for all of them (e.g. if the ring is ill-defined over a larger part, you will need some manual intervention like drawing its border there:
- split channels, delete all but the red one.
- Process>Filters>Maximum with a radius of 3.5 or 4 to close the circle
- Threshold 0-230
- Use the wand in 4-connected mode on some red pixel inside the circle
- Edit>Selection>Enlarge by approx. 4 pixels
- Measure to get the area
Michael
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On Jul 24, 2012, at 17:22, Broncosbeatall wrote:
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