Have seen tutorials for Photoshop with Blend If tutorials explaining how it works and how to use it with texture creating, but the biggest problem is I haven't Photoshop and in GIMP 2.6 this feature just missing... I'm using GIMP 2.6.11 and I'm looking for similar feature as a plugin for GIMP 2.6 releases (including 2.6.11)... I've made an image how it may look like with little explaining: 'This layer' slider modifies active layer depending on its own luminosity, 'Underlying layer' (I have wrote 'Underlaying layer', please expect my mistake) modifies the active layer depending on layer sitting straightly under it. Because 2.6 releases cannot work with layer modifiers, the plugin may make a layer mask to the active layer and if isn't checked particular checkbox, the layer mask is even applied... I've written 'Make layer mask instead of adding alpha bits' and explained the tool makes bitmap changes on the layer, that's the difference from Photoshop tool. Adding alpha bits simply means making layer mask depending on input informations and applying the mask... What's useful in Photoshop, the GIMP can have already as a plugin.