Before proceeding with this topic you need know how to work with selections. The opacity is a value stored in the alpha channel of an image. It permits to adjust the visibility/transparency of the image.
When the opacity of a pixel is set to 255, the pixel is totally opaque. It means that when you draw it on a background image (like displaying an icon on Windows® desktop), you don't see this image "behind" the pixel. The pixel is 100% displayed over the background. When the opacity is 0, the pixel is totally transparent. In such a case you simply see the background. If the opacity is set to 128 (50%) you see the pixel and the background 50%-50%.
Opacity is set pixel by pixel in an RGB/A image. It permits to create very nice effects (light shadows, halos, semi-transparencies, smooth edges...).
The opacity adjustment feature included in Axialis IconWorkshop™ permit to change the opacity of a selection of pixels. Adjustment is made in percents from -100% (more transparent) to +100% (more opaque). This feature is very interesting for floating selections. It permits to add semi-transparent overlay objects to existing icons.
This feature works only with RGB/Alpha Channel image formats.
1. Select a region with the selection tool or paste a floating selection. If no selection is active, the adjustments will apply to the whole image.
2. Choose Draw/Adjustments-Effects/Opacity or press "O".
3. The dialog box Adjust Opacity opens.
4. To get a better idea of the adjustments you're doing, we recommend you to activate the Preview option. It permits you to see the changes in background (editor and preview windows).
5. Specifies the Opacity value you wish to add to the current image. The value you specify is added (or subtracted if this is a negative value) to the current image opacity. Valid values are in range -100 (more transparent) to +100 (more opaque).
6. When done, click OK.