I used to do this all the time. I have a folder full of masks (deckled paper edges, etc) that I used to use all the time. But now for the life of me I can’t remember HOW. I’m suing Photoshop CS4. I know how to create a layer mask and paint in black and white to mask things out, but what I need to do is use a black and white image as the mask. I haven’t been able to paste the image into the mask, nor have I been able to set a separate layer as a mask. I can set one as a clipping mask, but that’s it. I’m not even sure what a clipping mask is.
Does anyone out there know how to do this very simple thing and can remind me?
Open the greyscale image in photoshop, select all and copy it.
Open the doc you want to use this in as a mask.
In the Channels palette, create a new alpha channel (Under the Channel palettle drop down, select New Channel, or click the icon at the bottom of the palette that looks like a clean, new page)
Paste your “mask image” into this new alpha channel. You may need to size this using Transform/Scale.
On a Mac, you Command-Click on an Alpha Channel to convert it into a selection. If you’re in Windows, it’s probably something similar. Just hold your cursor over the new alpha channel, and hit one of the modifier keys until your cursor changes into a little “selection icon”, the just click on that channel… voila! A selection is born.
From here, you can do whatever you can do with any ol’ selection, including creating layer masks (not to be confused with alpha channels).
Thank you! Although I’ve never done it that way before which makes me suspicious that there is another way to do it… but that worked well enough so it’s good enough for me!
On the other thing, I think you’re referring to a clipping path. It’s a vector based bezier curve you can use to define where the image will “clip” or outline if brought into page layout apps, like InDesign.
These are made with the Pen tool, located and stored in the Paths palette, and to define as a clipping path, you’d need to click on the Path palette’s drop down menu, and select “Make Clipping Path” to define it as such to an external application that can recognize it.
But paths are of course useful for much more than just clipping paths. I use them a lot to create very smooth, and low-memory selections, sort of an alternative to alpha channels, but without the ability to retain greyscale information. It is indefinitely scalable though like any other vector path.
No, I’m most decidedly NOT referring to that. I’m referring to using a grayscale image that you insert as a new layer in some fashion and use it to mask transparency for another layer.
Select All on the image to be used as a mask, and Copy. Set up your layer and mask. Option/Alt click on the MASK thumbnail in the layer–this puts an image of your mask (which will be all white or all black) in the document viewing area. Paste in your image. Click on the Image thumbnail to set the view back to your image.
