View Full Version : Creating transparency from a grayscale layer

10 October 2005, 08:27 PM
I have a grayscale layer (layer A).
I would like to convert this layer to a new layer (layer B) with transparency.
- Black pixel of layer A would give a full transparent pixel in layer B
- White pixel of layer A would give a full opaque pixel in layer B, and
- 50% gray would give a pixel with opacity of 50% in B.

I do not want to have an alpha channel, but just to have a layer with its transparency based on my grayscale layer.

Thank you.

10 October 2005, 11:20 PM

Use layer masks, a layer mask will affect your layer using a grayscale image.

To do this:
- Select your grayscale image (if it is in color photoshop will automatically convert it to grayscale anyway). Select the whole image using ctrl-a (or select a portion of it) and copy it using ctrl-c.
- Select the layer that will be affected and 'add layer mask' (it's the 2 button at the bottom of the layers palette, or Layer>Add Layer Mask>Reveal All
- In your layers palette alt-click the mask to view it (it should be all white at that point), and paste (ctrl-v).
- Click on the layer thumbnail (not the mask thumbnail) and you should be done


11 November 2005, 04:10 PM
well, if it's greyscale and you want white at full opaque and black at full transparency, cant you just set the layer style to "Screen?"

reread, yeah the guy above me seems correct :)

11 November 2005, 06:42 PM
To do this:

Thanks a lot, exactly what I was looking for.

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11 November 2005, 06:42 PM
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