Useful Equalize feature?

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Charles2
Posts: 225
Joined: November 24th, 2009, 2:00 am
What is the make/model of your primary camera?: Fuji X-Pro 2
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Useful Equalize feature?

Post by Charles2 »

DxO PhotoLab has a smart lighting dialog. It's a good idea, although the implementation is not the best, in my opinion.

With this in mind, one can imagine a (helpful?) feature for Equalize. Let the user draw a rectangle on the image. The equalization is then performed for the entire image (or for the area masked normally) based on the pixel values in the selected region.

To be more elaborate, the selected region could be a subset of the operations in the Mask dialog, perhaps the first five area tools in the Mask dialog (from the left on the third row of options).

I have not explored how helpful this option might be. In the case of a rectangular region, you can do the same thing if you add a splitter, go to the second branch, crop to the desired region, Equalize there and save the settings, then return to the first branch and apply the same Equalize setting.
jsachs
Posts: 4203
Joined: January 22nd, 2009, 11:03 pm

Re: Useful Equalize feature?

Post by jsachs »

What I normally do is to use the Brightness Curve transformation which gives you more direct control than Equalize.

When using Brightness Curve, you can create a mask of some region using the normal mask tools and then, by clicking on the histogram button in the upper right corner of the dialog box, you can see the histogram of just the masked area. You can then create a curve that adjusts the brightness and contrast of the masked area based on its histogram while watching the effects on the output image.

As an added bonus, by clicking on the black curve button next to the histogram button, you can apply a different correction curve to the unmasked areas (where the mask is black) so for example you can make one part of the image lighter and the rest darker in a single operation.

There is an example of this technique in Transformations.pdf under Brightness Curve.
Jonathan Sachs
Digital Light & Color
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