“Local Edit” Processing Tab
This tool allows you to correct specific parts of the image.
In principle all filters on the other tabs work on the whole image, though they might be constrained by global masks (like a luminance mask in Gimp). The difference with this tool is, that the masks used for calculation are local. So, when you add a new spot, you click on the image and Photivo gets the position and the color values of that pixel. Starting from these two values a local mask is calculated and the luminance curve as well as the saturation and hue adjustments are applied only to pixels inside that mask. The mask consists of all pixels that have similar color values as the starting pixel and can be connected to the starting pixel on a path of only such pixels.
Example: Consider an image with a blue sky and a tall building in the middle that extends beyond the top of the image, essentially cutting the sky into two unconnected parts. When you choose the normal saturation curve to adjust the blue values, both parts of the sky get the same effect. With spot tuning you can create a spot each and adjust the two parts of the sky independently.
Brother John was so kind to prepare a short feature video which shows the basic usage of this new tool.