Bug 232585

Version:           1.1.0 (using 4.4.1 (KDE 4.4.1), Mandriva Linux release 2010.0 (Official) for i586)
Compiler:          gcc
OS:                Linux (i686) release 2.6.31.12-desktop-3mnb

I have a request for a new feature in the digiKam editor. Many years ago I used a image manipulation program called Picture Publisher, which had a nice feature for visualising the effect of changing the colour balance or lightness/contrast.

Basically, a dialogue is shown, divided into a 3 × 3 table, each cell showing a scaled down version of the original image, with the effect being applied the images. The middle image is the original, and on the right the first effect is applied ‘positively’, and on the left it is applied ‘negatively’. Similarly, for the top row the second effect is applied positively, and on the bottom row it is applied negatively. For lightness/contrast, the effect would be that, for example, the upper right image is ligher and with more contrast, and the lower right one is darker and with less contrast. It’s a bit difficult to explain, but I’ll attach a couple of images showing what I mean. The amount of each effect applied is chosen using two sliders below or at one side of the images.

When the the user clicks on one of the 8 surrounding images (or change the slider values), the middle image is immediately replaced with that one, and the whole process is repeated. This makes it very fast and easy to iteratively adjust the image. Example of though process:

I think the image is too dark. I’ll click the image on the right. Still a bit to dark – click on the right one again. Perhaps a bit dark still, and needs more contrast – click on the top-right image. OK, it now needs just a bit more contrast, and it turned out slighty too bright – adjust the lightness slider and click on the top-left image. OK, now it’s perfect – click OK to close the dialogue.

This feature could also be used for choosing the RGB balance, but instead of crossing the two filters (left to right and top to bottom), each row would correspond to one colour, so that the entire middle column would consist of the original image. Alternatively, one colour (e.g., red) could be ‘fixed’, and the layout only consisting of changes to the two other colours.

I’ll attach two image which should illustrate the features. Of course, the feature can be used for every situation where you combine two filter effects.