Hey everyone, i've been searching the internet everywhere but I can't find anything close to what I'm looking for, and I was just wondering if there was some kind of tool that could add opacity to a layer, like say in brush form.
To put it differently; the eraser tool is a brush that removes opacity in a certain area of a layer, I am looking for something that does the opposite, something that will add that opacity back. Any thoughts or workarounds?
Well, there has to have been pixel data there in the first place. There is no tool that can arbitrarily "manufacture" opacity where there was none to begin with.
So for instance, applying the eraser tool to an area where the pixels started out as 100% opaque is a destructive operation. Aside from direct Undo/History backtracking, the edit results in lost data that can't be recovered via a brush function...EXCEPT via the History Brush. You can paint opacity back in based on a History state from before the erasure. Read up on History Brush.
More elegantly though, the true answer lies in Layer Masks. The whole idea behind layer masking is opacity that's 100% editable in either direction using a wide array of tools, settings, and techniques.
So the boiled down answer is yes, Photoshop can re-add opacity via the History Brush and Layer Masks.
All of the vim with none of that annoying vigor.
Daniel, if for one of many reasons you can't use the history brush, try this:
-Duplicate your layer many times and merge all the duplicates into one layer (but don't flatten them onto your original layer if you'd like maximum adjustability.)
-Put a "hide all" layer mask on the NEW layer, the one made from all the duplicates
-Grab a white brush and paint on that layer mask--voila! You have made your own opacity brush.
I do this often when I have made transparent brush strokes I later wish to emphasize--in this case there is no history to go back to.
I think, and John may disagree, this suggests that an opacity brush is theoretically very possible. Even if photoshop doesn't know the hue/lum/sat of a transparent pixel (and I suspect it does, alpha information should be separate from other channels) it can obviously calculate the result if the pixel is stacked many times on itself.