Colour balancing - green reduction - changed the question

[geoland]

This image was processed by removing background tint and using Fred's autowhite colorbalance and curves scripts as follows.

Code: Select all

convert stack.tif -depth 16 -channel all -normalize +channel +normalize +compress -alpha off 2.miff

	./autowhite 2.miff 3.miff

	./colorbalance -c g -a 15 3.miff 4.miff

	./curves -g C "25,75" 4.miff stack_devel.tif

The result is exceptionally good. However, it would be preferable to filter out more of the green, retaining the luminance provided by the green channel without the tint.

I am seeking suggestions about the best way to go about doing this automatically with a degree of certainty, rather than manual adjustment to the image.

[fmw42]

Was that the original or the result? It might help if post both, so others can experiment.

[geoland]

This is the source 16bit tif file ~72MB

[fmw42]

One suggestion would be to process the original in Photoshop or GIMP. Then create 3D Hald image in ImageMagick and take it to your Photoshop or GIMP, then apply the same adjustments (as long as they are global changes and not local such as sharpening or convolutions) to the Hald Image. Then bring the Hald image back to ImageMagick and use it to apply to all your other similar photographs.

[geoland]

With a little more experimenting, I find the colorbalance reference channel makes a difference image to image. Referenced to Blue the example image is nicely representative. Other images benefit from Red or Green.

[fmw42]

Have you tried -color-matrix? That might help, but it does need some effort to learn.

[geoland]

Thanks Fred, I have. I am using -color-matrix for applying channel multipliers to images from DSLRs without an astronomical filter mod. The user can add up to 5 matrices. It is a little intensive for developing a preview. And I may have asked the question too soon. Your scripts do precisely what's required. I just need to play a bit more. Every new feature is a new learning curve...