ResonanceDesign

How can I turn a black and white(and grey in the middle) opaque picture into a transparent PNG (or produce a transparent mask), where the different shades of grey represent different levels of alpha transparency. Black meaning fully opaque and white fully transparent.

I found myself having to look this one up everytime I use it(seemingly not that often), so as a reminder and to add an entry to the search results if anyone else wants to know how to do this one(I never found a easy detailed tutorial for this), so here it is:

Given the below one is the image that you want to turn into transparent.

Open the layers window, if it isn’t open yet. Highlight the layer. Mark it and copy it into the memory (apple+A, apple+C).

Create a new layer.

Create a mask for this layer by clicking the mask tool(rectangle with circle in it) at the bottom of the layer window.

Now switch to or open the channels window. If you made sure, the layer you created the mask for is highlighted, then the channel window should show a mask channel called ‘channelName’ mask.

Paste the image that you copied earlier into the mask layer.

Then invert the mask(apple+I).

Switch back to the layers window. You can now switch off the original layer’s visibility.

Anything you now copy into the masked layer will be masked. In order to have a monochromatic version of the black and white image, just fill the layer with a single color, like blue.

Or black. The reason to do this, is if you mask the original image, edges might appear at the end.

You can now export the above as PNG-24. I found that the mask is not always as dark as the original, so sometimes, I just duplicate the masked layer as 40% alpha, which adds opacity throughout.

That’s it, have fun PNGing the world.