What is a mask?

JF
Posted By
jay_fresno
Mar 30, 2009
Views
710
Replies
9
Status
Closed
Can anyone define what the term mask means in Photoshop — there are quick masks, layer masks, saved selections, etc. Is there an overall definition for all of the types of masks?

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H
Ho
Mar 30, 2009
You left out Alpha channel. I’d write you a thesis, but I have a bowl of ice cream waiting. Google it or wait for someone with nothing better to do to answer.
JF
jay_fresno
Mar 31, 2009
Ho,
I did do a search on Google, but didn’t find any straight forward, simple answer. I gather from your response about a "thesis" that there is no simple straightforward answer. In typical Adobe fashion, a term such as "mask" that is so integral to Photoshop, cannot be defined without a thesis.
Enjoy your ice cream!
JR
John_R_Nielsen
Mar 31, 2009
A grayscale bitmap that shows/hides the image, depending on the pixel value of the mask.

See also alpha channel.
P
Phosphor
Mar 31, 2009
Mask = Channel = Selection. Different aspects of the same thing.

If you can find it, there’s an out of print book called Channel Chops: < http://www.amazon.com/Photoshop-Channel-Chops-David-Biedny/d p/1562057235> Good a thesis as you will find anywhere.
DM
dave_milbut
Apr 1, 2009
a mask covers something up.
B
Buko
Apr 1, 2009
What is a mask?

Its what was worn by Jim Carrey in the Movie "The Mask"
GA
George_Austin
Apr 1, 2009
Jay,

A mask is a gray-tone map. Period.

You asked for a simple definition. You got it. But clearly that’s not much help, so let’s dig a little deeper.

The tone of gray at any pixel site determines the opacity at that point. Black equates to zero opacity and white to 100% opacity. All of the intervening shades of gray represent the full spectrum of opacities linearly.

Even though rubylith appears by default in a quick mask it, nevertheless, represents gray and is used as a visibility crutch. Any other color can be substituted for rubylith when it beomes difficult to distinguish between the masker and the maskee, so to speak.

The opacity range of the rubylith itself (or its substitute) is independently selected by the user, again for visibility. Thus a rubylith opacity range from 0 to 40%, say, might be used to represent the full black to white gray scale

Perhaps you now see how quickly this can escalate into the thesis Ho sidestepped. As a fellow ice-cream lover, I’m off to the fridge!
GA
George_Austin
Apr 1, 2009
Jay,

A mask is a gray-tone map. Period.

You asked for a simple definition. You got it. But clearly that’s not much help, so let’s dig a little deeper.

The tone of gray at any pixel site determines the opacity at that point. Black equates to zero opacity and white to 100% opacity. All of the intervening shades of gray represent the full spectrum of opacities linearly.

Even though rubylith appears by default in a quick mask it, nevertheless, represents gray and is used as a visibility crutch. Any other color can be substituted for rubylith when it beomes difficult to distinguish between the masker and the maskee, so to speak.

The opacity range of the rubylith itself (or its substitute) is independently selected by the user, again for visibility. Thus a rubylith opacity range from 0 to 40%, say, might be used to represent the full black to white gray scale

Perhaps you now see how quickly this can escalate into the thesis Ho sidestepped. As a fellow ice-cream lover, I’m off to the fridge!

Master Retouching Hair

Learn how to rescue details, remove flyaways, add volume, and enhance the definition of hair in any photo. We break down every tool and technique in Photoshop to get picture-perfect hair, every time.

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