Quote:
Originally Posted by dlaf
Hi jiminy,
Well, I think I understand layers pretty well when I'm working with raster and vector layers for flyers, brochures, and working with different graphic images, but once it switches to masks and photographs... well, I just don't get why a mask is different than a layer and why a mask is needed when, can't a regular ole layer do the same thing? Which leads me to think I just don't know what is different about a mask. It all turns into one big swirling circle of a thought process! Was that clear as mud?
Debbie
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(I'm a gimp user, and I'm fairly sure PS is the same for masks so here it goes)
Basically, a mask controls what part you can see, and what parts the program gets rid of, in a layer. In it's simplest possible use, that would mean you could apply a layer mask to a picture, paint an area on the layer mask black, and as a result, the program will make any area on the picture where the mask is painted black transparent. It's like that black section on the mask punches a hole through the layer, through to to whatever is below.
A more common application of this is to overly sections of photos taken from the same position. Imagine you're out the front of a busy tourist site, tripod in hand, and want to take a picture of the building itself without the tourists. You set up the tripod, and take a bunch of exposures, then head home.
Now, when you open each image up as a layer in photo shop they'll be exactly aligned. You then add a mask to the top layer, and proceed to paint a black section on the mask anywhere that those pesky tourists are standing. This means that section of the layer becomes transparent, so you can see another one of your exposures underneath in that small section.
Odds are, people have moved around between photos, so you should be able to see more of the building. You then repeat the process with the next layer, adding a mask and 'painting out' all the tourists.
By the end, you would be able to see the building without any tourists as a result of taking the bit of the building you can see from plenty of pictures.
Now, yes you could have done this with the erase tool for arguments sake. However, a layer mask offers you much more flexibility in the way you lay it out, and the changes you can make as you go (it's a royal pain to realise after twenty minutes that you've erased a bit too much, and have to revert and start over). Also, in a lot of applications it's easy to just use a layer mask and the gradient tool to combine sections of layers.
So what makes a mask different to a regular old layer? It is actually a layer modifier, in that it changes what you can and cannot see of the layer.
Could you do the same thing with a regular layer? Yes, but not with as much control and flexibility.
I have absolutely no idea if that helped, told you everything you already knew or just confused things more, but it was worth a shot. And I'm pretty sure I learned about layers from a photoshop tutorial, so it and the gimp must be pretty similar....