Web Design Photoshop Tutorial: Alpha Channel Selections

Posted Tuesday 24th Jan 2012 by Kim

In my last post I gave away some freebie sales stamp brushes.  Quite a few people have asked me how I created the grungy texture on the stamps so I thought I’d give you an insight into how to subtly remove sections of a flat image using Photoshop Alpha channels to give it a more organic feel.

Finding The Right Texture

First of all you need to locate the source image for your texture. The image you choose can affect the overall outcome quite dramatically. I used an image from a texture set on DeviantArt which I trawl frequently for images to use in my web design. I selected this image because the scratches provide some high contrast lines which will help later for the Alpha Channel selection.

Threshold Adjustment

Load your image in Photoshop and hit cmd-J to make a copy of the layer (I do this out of habit so that I always have an untouched copy of the original source image as the background layer when making adjustments).

Now select Image -> Adjustments -> Threshold. This divides the image into black and white values. Drag the slider to the right. The idea is to retain the scratches as far as possible as the white data will become the area you will be looking to remove from your flat image. Apply the adjustment and make a selection of the whole layer by either using the marquee tool or pressing cmd+click over the layer thumbnail. Store the layer on the clipboard by hitting cmd-X.

Alpha Channel Selection

Open your flat image and make a layer copy by pressing cmd-J as before. In the Channels palette click ‘Create New Channel’. A new channel called ‘Alpha 1′ should appear. Select the new channel and your image should disappear and be replaced by a black screen.

Press cmd-V to paste your black and white texture image into the channel. Now click the ‘Load Channel As Selection’ button. You should see a selection made out of the white areas of the image.

Finally click on the layers palette and select the duplicate layer of your flat image. Hit backspace on your keyboard and the selected area will be removed from your flat image giving it a subtle roughened look. You can use all sorts of different textures and combinations of textures in different alpha channels to produce different effects on images and text. Happy experimenting!

By Kim

Kim spends many hours of his life finding out random things about Photoshop. He also likes running, cooking and eating the things he cooks after running. See all of posts.

  • http://venturamovingandstorage.com Janey Smith

    Thanks for showing us, great tutorial!

  • Luci

    *bookmarks* nice tutorial, Kim! I’m already using it a lot!

  • Adam

    Cheers for the great tutorial mate, i will be definitely be trying this today.