Channels versus Masks

[Five Photos]

I just watched the very interesting tutorials about channels and how to apply selections to such. This is a simple question: could somebody please explain me the difference of storing a selection in a channel rather than as a mask? What are the main differences, advantages, or disadvantages? Thanks.

[toltec]

Hi Five, glad to see you are alive! and on this forum.

 

Selections and masks are quite similar in that they isolate an area, however ...

 

A selection, selects the area you want. You may want to adjust the colours in just one place..

 

A mask, masks out the area you don't want (hides it), Like the above (but the opposite way round) it allows you to just modify an isolated area.

 

Both approaches allow you to cut out and copy say, one person from one picture and paste into another picture. A selection pastes just the area you selected. With a mask however, you paste not just the cut out person, but also the whole surrounding image untouched (but hidden). Handy In case you ever need it later, but the drawback is larger file sizes.

 

If you just want to adjust the colour of something, a selection is usually quicker and easier.

 

The advantage of saving selections to channels is that you can retrieve them and sometimes it's useful to build up a complex selection in stages. As an example, select the body and feather the selection edges to blend it in to its new surroundings, select the head and hair and refine the edges around the hair separately. You could not feather around the hair because it would vanish. Join the two selections into one selection by loading them from the channels..