CODEWITHSUNDEEP
gimppython-fu
Loma Harshana
Loma Harshana

Reputation: 661

GIMP - Get a point within selection from python script

My script runs on a fuzzy selected area. I need to get the color value of the selected area from within python-fu script. This could be the average value of the selection area or, better, the color value of the pixel that user clicked on to make the fuzzy selection.

I can get the selection bounds and then somehow get a point within the selection to make use of pdb.gimp_image_pick_color. But I don't know how to get the point (which best represents the color of the selection) within any arbitrary shaped selection.

Could you please help?

Upvotes: 0

Views: 168

Answers (1)

xenoid
xenoid

Reputation: 8904

A point inside the selection could be tricky, because you don't know if the selection is a single contiguous area.

Two ways to do it:

Using the histogram over the selection

You can use pdb.gimp_drawable_histogram to get histogram values for each of the RGB channels in the selected pixels

mean, std_dev, median, pixels, count, percentile=pdb.gimp_drawable_histogram(layer,HISTOGRAM_RED,0.,1.)

Using the call three times (once for each channel) in this image selection:

enter image description here

        | Average | Median |  Picker
--------+---------+--------+---------     
  Red   |   44.0  |  44    |    47
Green   |   54.2  |  54    |    56
 Blue   |   43.6  |  43    |    46

The values obtained for the same area with the color picker in average mode aren't so far off.

Using the color of a pixel

  • You can transform your selection in to a path with pdb.plug_in_sel2path(image, drawable). The result is a new path that is set active, so you can obtain it with path=image.active_vectors
  • You can check that you have a single stroke in path.strokes (otherwise you have a non-contiguous selection).
  • The list of all coordinates of the anchors in the single path stroke is:
allX=path.strokes[0].points[0][2::6]
allY=path.strokes[0].points[0][3::6]
  • If you average these two lists, you get the coordinates a pixel near the center (and hopefully, inside the selection if the selection is reasonably convex)
  • You can get the color of this pixel with pdb.gimp_drawable_get_pixel(), but this color may be quite different from the rest (in my test image above, the center pixel is (54, 62, 47), so somewhat lighter and redder than average).

Upvotes: 3

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