Grayscale to semitransparency?

[dalgard]

Hi!

How do I convert a grayscale image to an image consisting of all black with different degrees of opacity (on a white background)?

If I apply the inverted image as a mask on an all black layer I get pretty close - but the result is darker than the original, which frustrates me to no end. If I set opacity for the resultant image to around 80 % it fits better.

Thanks for your help!

 

[dalgard]

Okay, if I work in grayscale the result actually doesn't become darker than the original! So it must have something to do with some human perception algorithm that is only active in color mode... Hmm.

Edit: ... Or? Now I can't get it to work again! Arrgh! Becomes darker.

Edit: Okay, the reason I couldn't get it to work again was because I had pressed undo and it had then reverted to RGB mode! Now I'm having trouble with a semi-transparent layer becoming lighter when I change the mode to grayscale...... I won't go into that, though, since I've found a free plugin that works beautifully - it's called Ghost and can be found on the website of Flaming Pear under Goodies!