Convert to Alpha

Blue Ten · 04-16-2008, 01:37 PM

I have a question about converting black and white images (line art) to alpha -- i.e. black-to-transparent images.

I have used Fireworks before and it had a very useful filter under "Other" called "Convert to Alpha". I would use this whenever I wanted to work with my scanned drawings. Hehe, sadly, I don't have Fireworks anymore (was not mine), just CS3 Design Premium.

Anyway, I was wondering if there was a way to achieve a similar result in Photoshop CS3 -- APART from adjusting the blending mode of the line art layer to "Multiply". What I want is the ability to lock out transparent pixels and colorize the line art itself; Multiply is just cosmetic and won't allow this. It would be great if there was some process for this conversion in Photoshop... I'd just make an Action out of it and use it each time :P.

Failing that, is there a program out there that specializes in converting grayscale images to alpha, preferably one that saves them as PNGs or PSDs? I've searched, but haven't been able to find one yet...

This forum has always been a big help to me. Thanks in advance

.

**freddyhard** · 04-16-2008, 02:39 PM

i'm not sure this is what you want to do, but you can copy and paste the line art image into a mask layer created on a image you want to hide out.
open the line art image and select all then copy.
open the image you want to hide (cannot be background layer).
create mask layer ('add vector mask' button on bottom of layer panel)
press left ALT and left click on the newly created mask layer - this will isolate all other layers and present you with the mask layer to modify.
then paste the copied line art image onto this layer. anything that is black will be hidden and white will be visible.
then ALT - left click on the mask image to resume normally and voila.

the image will now be hidden by the black and white pixels on the mask layer. i might not have explained this very well... there are others here who know more than i and they might have a go if i am wrong.

scunny · 04-17-2008, 08:36 AM

Click Select-Colour range...
use the eyedropper to select white area on your image, leave fuzziness set @ 100
Click OK
Hit Del to erase white area of your image (make sure layer is not locked)

OR if you want to create an actual alpha channel...

Select colour range as above, then...
Click WIndow-Channels
A box should appear
Click new channel (at bottom right of box)
This channel should be auto-named 'Alpha 1' the image should go black
Click Edit - Fill...
Contents - Use: scroll to 'white'
Blending-normal, opacity-100%
Click ok
Now if you save as a TIFF or other alpha supported format, an alpha channel should be embedded in the file.

Hope this helps.

04-16-2008, 01:37 PM	#1 (permalink)
Blue Ten Registered User Join Date: Jan 2007 Posts: 28 OS: Vista Home Premium My System	Convert to Alpha I have a question about converting black and white images (line art) to alpha -- i.e. black-to-transparent images. I have used Fireworks before and it had a very useful filter under "Other" called "Convert to Alpha". I would use this whenever I wanted to work with my scanned drawings. Hehe, sadly, I don't have Fireworks anymore (was not mine), just CS3 Design Premium. Anyway, I was wondering if there was a way to achieve a similar result in Photoshop CS3 -- APART from adjusting the blending mode of the line art layer to "Multiply". What I want is the ability to lock out transparent pixels and colorize the line art itself; Multiply is just cosmetic and won't allow this. It would be great if there was some process for this conversion in Photoshop... I'd just make an Action out of it and use it each time :P. Failing that, is there a program out there that specializes in converting grayscale images to alpha, preferably one that saves them as PNGs or PSDs? I've searched, but haven't been able to find one yet... This forum has always been a big help to me. Thanks in advance . Last edited by Blue Ten : 04-16-2008 at 01:43 PM.

04-16-2008, 02:39 PM	#2 (permalink)
freddyhard Design Team Member Join Date: Apr 2005 Location: Éire Posts: 1,463 OS: 2k (still!)	Re: Convert to Alpha i'm not sure this is what you want to do, but you can copy and paste the line art image into a mask layer created on a image you want to hide out. open the line art image and select all then copy. open the image you want to hide (cannot be background layer). create mask layer ('add vector mask' button on bottom of layer panel) press left ALT and left click on the newly created mask layer - this will isolate all other layers and present you with the mask layer to modify. then paste the copied line art image onto this layer. anything that is black will be hidden and white will be visible. then ALT - left click on the mask image to resume normally and voila. the image will now be hidden by the black and white pixels on the mask layer. i might not have explained this very well... there are others here who know more than i and they might have a go if i am wrong. __________________ "It takes two to lie, one to lie and one to listen" Homer

04-17-2008, 08:36 AM	#3 (permalink)
scunny Registered User Join Date: Apr 2008 Posts: 1 OS: xp sp2	Re: Convert to Alpha Click Select-Colour range... use the eyedropper to select white area on your image, leave fuzziness set @ 100 Click OK Hit Del to erase white area of your image (make sure layer is not locked) OR if you want to create an actual alpha channel... Select colour range as above, then... Click WIndow-Channels A box should appear Click new channel (at bottom right of box) This channel should be auto-named 'Alpha 1' the image should go black Click Edit - Fill... Contents - Use: scroll to 'white' Blending-normal, opacity-100% Click ok Now if you save as a TIFF or other alpha supported format, an alpha channel should be embedded in the file. Hope this helps. Last edited by scunny : 04-17-2008 at 08:48 AM.