Digital Light & Color

I wanted to lighten some parts of an image with its lighter version (Brightness Curve).
I used my favourite method Clone Transformation Tool, One to One, the source image Brighten Curve step.

I switched to Display Input and Preview Side by Side and started cloning.
Then I switched to Display Preview to see the results better, but I got the source image preview - the Brightness Curve preview. I would expect the Clone preview with the result.
When I checked the Display Input, I got the expected Brightness Curve preview.

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Out of curiosity I tried another method with the same images. This time I used Composite Lighten method with some masking. The Overlay was the brightened one.

When I created the mask from the Composite Amount icon, switching between Display Input and Display Preview buttons in Composite dialog showed correctly either the Resize preview with the masked area, or the Composite preview with the result.

However when I created the mask from the Composite Overlay Amount icon, switching between Display Input and Display Preview buttons showed always Brightness Curve preview with the masked area.
Display Input and Preview Side by Side showed both previews correctly.

If I understand you correctly, this depends on whether you select the main image or the input image in the image browser. When you use Clone from one image to another, the image you are cloning from is selected. You can select the main image by clicking on it in the image browser and then the display buttons will work normally.

I found it unusual that, though you can display in the joint preview both images, the individual previews both show only the source image. This seems to me a bit confusing and makes the general behaviour of the display buttons inconsistent.

Currently if you need to see the images independently you can:
1. either click on them directly in the image browser - this option overides whatever preview button is turned on in the transformation dialog

2. or make active the input image in the browser and then toggle between Display Input and Display Preview on the transformation dialog - this option however replaces the source image preview on the left making it impossible to continue with cloning. So in the end you have to make active the source image in the browser again. This is not very practical.

If it is possible to display both images next to each other only with the source image active why just not hide one or the other depending which button is on?

Or have I missed something?

I'll take another look at this.

Fixing this has proved a lot more complicated than I expected, but I am almost finished with the changes.