5 Replies - 10792 Views - Last Post: 02 May 2012 - 05:24 AM

#1 e_i_pi  Icon User is offline

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Grayscale to transparent scale in Photoshop

Posted 02 April 2012 - 08:26 PM

I'm using Photoshop CS5, and I'm trying to convert a grayscale image to transparent scale. Basically, if something is 75% black, then it would become black with 25% transparency.

I know there was a plugin called Eliminate White that worked with Photoshop 3 and 4, but I can't get it to work with CS5. Does anyone know a plugin or a technique that can be used to achieve what I'm after?
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#2 gattigen  Icon User is offline

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Re: Grayscale to transparent scale in Photoshop

Posted 09 April 2012 - 03:30 PM

The best way to do this is with an alpha channel, there will be no plugins necessary. What you will want to do is take your gray scale image and invert the color (image>adjustments>invert, then marquee select the image and copy it (ctrl + c). In your layers panel, there is a channels tab, click the tab and then look at the bottom of the channels panel and click create new channel. it will default to Alpha 1, but you can name it anything you want. click on that channel (make sure that it is the only one selected) and paste (ctrl + v)the copied image into the alpha channel. Deselect the image (ctrl + d, then click on the alpha channel to highlight it, then click on the icon at the bottom of the tab called load channel as selection (two icons to the left of the new channel button). go back to the layers tab and create a new layer, then select a paint brush and make the paint brush very large. once you have a large paint brush, paint the selection with a color of your choice. Anything that was black will become transparent and anything that was white will be the color that was painted and it will do a gradient between those two colors.

Hopefully I didn't forget a step.
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#3 e_i_pi  Icon User is offline

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Re: Grayscale to transparent scale in Photoshop

Posted 10 April 2012 - 05:36 PM

Thanks heaps, that makes sense. I'll test it out when I get home. I've never used the channels tab before, noticed it was there, but never really knew how to use it. I'll be making white transparent (not black), but it should simple to change the technique to be appropriate. Again, thanks :)
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#4 gattigen  Icon User is offline

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Re: Grayscale to transparent scale in Photoshop

Posted 10 April 2012 - 07:19 PM

It is not necessary to change anything about your grayscale image. If you invert your images color you will be able to do things the same way, and allow the program to prepare the image for use in the alpha channel.
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#5 e_i_pi  Icon User is offline

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Re: Grayscale to transparent scale in Photoshop

Posted 11 April 2012 - 12:07 AM

Just tried it at home. Perfect and brilliant. Thanks heaps, 10/10 solution.
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#6 Shane Hudson  Icon User is offline

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Re: Grayscale to transparent scale in Photoshop

Posted 02 May 2012 - 05:24 AM

Nice one gattigen, I have been using Photoshop for over 10 years now and completely forgot about that method!
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