layer mask question - DPChallenge Forums

Canon EF 17-40mm f/4.0L USM

06/22/2007 10:03:14 AM · #4

If you use an eraser, the pixels on that layer are gone where you have erased it.

If you use a mask, the mask hides the pixels but doesn't erase them. You can delete the layer mask and be right back where you started with the additional layer.

I often use layer masks when I add filters to a new layer. This allows me to control the amount of filter that 'shows' through. If I just created a layer added a filter and used the eraser to get rid of what I didn't want, if I later changed my mind, I would have to start all over with that layer instead of just recreating the mask.

Hope that makes sense...

C

bdenny

Sony DSC-H5

06/22/2007 10:11:04 AM · #5

I've been trying to figure the same thing out lately. I always used the eraser because it seemed more straightforward. But it does seem to make more sense to 'hide' them instead of 'erase' them. You can always 'unhide' but you can't 'unerase'. Besides that functionality, I think it's the same thing.

awpollard

Canon EOS-5D Mark II

Canon EF 100-400mm f/4.5-5.6L IS

06/22/2007 10:15:34 AM · #6

Question about the Eraser: Can you not Un-Erase in Photoshop?

In Corel PSP Pro Photo XI it does a Smart Un-Erase. Where if you get too zealous with the eraser; for example you are removing a background and accidentally erase a persons ear, you can un-erase on the ear and the background will remain erased but the ear be visible. Basically it finds the edge that it thinks you on your layer.

Just curious

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

06/22/2007 10:15:57 AM · #7

Aside from the obvious "undoability" of the layer function, here's one more bit of added functionality: make the masked layer the active one and go to "load selection" and the default selection will be that layer's mask. So you can actually use your work on this mask as a selection for work on another layer and/or mask.

R.

SamDoe1

Canon EOS-350D Rebel XT

06/22/2007 10:17:35 AM · #8

What everyone has said is pretty much it. It's like the eraser tool, but not. With a mask, you can "unerase" if you mess up and it'll just go right back to the way it was before without having to step back in the history. You can also easily see if you've missed anything by using the "\" key which, in my opinion, is better than turning layers on and off to see where you missed.

kenskid

Nikon D700

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

06/22/2007 10:20:06 AM · #9

Hey... I didn't know about the " \ " key ! Thanks.

Originally posted by SamDoe1:

SamDoe1

Canon EOS-350D Rebel XT

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

06/22/2007 10:20:59 AM · #10

Originally posted by kenskid:

Hey... I didn't know about the " \ " key ! Thanks.

No problem, I randomly discovered it myself cause I missed the enter key, haha.

lovethelight

Canon EOS-5D Mark III

Canon EF 135mm f/2.0L USM

06/22/2007 10:24:19 AM · #11

"Aside from the obvious "undoability" of the layer function, here's one more bit of added functionality: make the masked layer the active one and go to "load selection" and the default selection will be that layer's mask. So you can actually use your work on this mask as a selection for work on another layer and/or mask. "

Thats cool! I didn't know that

thanks for everyones responses! I guess I will definitely be using masks more often now

bdenny

Sony DSC-H5

06/22/2007 10:25:15 AM · #12

Ok...so if I'm using layer masks I can hit "\" and it will show...the B&W layer? That's what I've been wishing I could do.
Also, if I mask the background from one layer, I can duplicate that mask on another layer by 'loading selection'?

Please say yes...please say yes.

SamDoe1

Canon EOS-350D Rebel XT

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

06/22/2007 10:27:32 AM · #13

Originally posted by bdenny:

If you hit "\", it'll show where you've masked in any color of your choosing. I personally use red and I'm pretty sure that's the default anyway. And yes, you can use the same mask on another layer by loading selection. At least I think you can.

06/22/2007 10:44:38 AM · #14

Originally posted by bdenny:

Yup, that's what I was saying in my post. Make the masked layer active and it is the default selection in "load selection"; once it's loaded switch to the working layer and it will be a selection on that layer/mask.

R.

Message edited by author 2007-06-22 10:46:06.

eschelar

Canon EF-S 17-55mm f/2.8 IS USM

06/22/2007 12:21:52 PM · #15

A few other really cool tricks with masks:

#1 - click on the mask so you are editing it.

Go to Image>Adjustments>brightness/Contrast and now you can use this to temper your delicate masks made from selections.

#2 - a somewhat more visual way of doing this and what Bear suggested is to click on the layer that has an existing mask, then going to channels. There will always be a channel in black and white that is the current layer mask. You can highlight this channel, then click the little dotted circle to turn this into a selection, then when you go to create a mask on ANY layer that doesn't already have a mask, the selection pops up for you already in place as the mask.

#3 - Channels are even more useful. If you want to create a mask that is fine and detailed based on what is in the shot, you can use the individual channels for content in the same way as described in #2 to create layer masks.

#4 - And you thought that was the end of the usefulness of Channels... I recently discovered how convenient this can be to rescue shadow areas in underexposed pictures (thanks to the student lighting crews... yeesh, ever hear of PRACTICING BEFORE THE PLAY guys? ;)... Check this out. Go to your layer, select all, then click on the mask to paste... aw dangit, that don't work! This is when you jump to your channels. Notice that you can click on RGB, it's just the whole normal picture. Now click on that little dotted circle. And go back to layers, add layer mask and PRESTO. Your picture is now a B&W mask, mapping all the highlight and shadow areas according to brightness. Now you can play with your layer and it's brightness, levels, curves, whatever strikes your fancy...

You can use it like this: Duplicate layer. Channels, RGB, Selection, layers, new layer mask, CONROL I (inverts the content, turning the mask into the NEGATIVE). Now apply heavy brightening (boost curves, levels, brightness/contrast, whatever) and watch your shadows come leaping to your beck and call, while your highlights are comparitively unaffected. There are lots of other ways of doing this of course and feel free to experiment with different layer modes (none of this is legal in basic of course - layer masks are not allowed) to get some real power, but it's amazing how quickly and easily you can grab your shadows back. (this is great for pre-CS2 users where this is essentially the long way of performing a 'shadows and highlights' tweak). Feel free to use brightness/contrast and such to really tweak it with finesse.

NOTE - it is usually best to make your selection based on areas that are not blown out or fully black... not much finesse there.

#5 - Oh yeah, it gets better than that too. You might want to work with Adjustment Layers instead of a regular layer and you want to do something similar to step three, you will go to the old habit of selecting a layer, hitting control A and copy, paste on the layer mask and... what the hey? oh yah, adjustment layers have NO REAL PIXELS in them, so what might work for a duplicated normal layer won't do a durn thing for you if you want to make a selection from the image as it appears after having been adjusted by the adjustment layers...

Let's say you want to do the same trick as in step 4, but you want to use a heavily brightened image to generate your selection, perhaps you want to beat your image with a hammer.

Create your curves layer FIRST, then push the heck out of it. NOW go to Channels, RGB, Select, and apply that layer mask... Now that adjustment layer that was strung out on juicy steroids can be easily scaled back down to a reasonable level... the selection remains as was set when the adjustment layer was wild and crazy.

*** When working with bringing shadow areas back and this type of edit, remember that a large part of what you are doing is bringing the image closer to the luminosity of a positive plus a negative. Wanna know what that looks like? It looks like flat grey... try it... Take any image, invert it, then set layer opacity to 50%... Nice flat grey all over the place... Think that makes your portrait nice and pretty? This is why it can be useful to have a difference in the selection. Tweaking the brightness/contrast of the mask can throw some naturalness back into the mix. Try turning the contrast DOWN by -40 and see how much better it looks. If you do this too neatly, you will end up with faces looking flat, grey and featureless. Not really all that desirable.

have a go with these!

06/22/2007 12:31:25 PM · #16

Originally posted by eschelar:

A few other really cool tricks with masks:

Nominated for "most useful post of the day"!

R.

eschelar

Canon EF-S 17-55mm f/2.8 IS USM

06/22/2007 12:36:36 PM · #17

hee hee! W00t! I knew all those hours crouched over my keyboard with Tablet Stylus in hand on mouse would pay off!

also known as 'how to bring back shadows in a severely underexposed picture in under 10 seconds'... makes a difference when trying to wedge mass photo edits in between cramming for finals... :) Walking back from grabbing a juice at the corner store, dividing images by hours and calculating number of seconds available per image in order to finish before the kids all graduate and disperse back to their homes around the country.

Message edited by author 2007-06-22 12:40:05.

06/22/2007 12:39:57 PM · #18

Originally posted by eschelar:

hee hee! W00t!

I confess I almost never use masks, mostly just masks in overlay and multiply mode that I paint on for dodging and burning, or for adding gradients. For the rest of it I make & store selections, then load them on dupe layers. It's an old, old working habit from when masks were a lot less sophisticated.

This post has inspired me to try some new techniques.

R.

eschelar

Canon EF-S 17-55mm f/2.8 IS USM

06/22/2007 12:40:49 PM · #19

thanks again for the positive feedback bear, you really don't know how much it means to me. really.

Delta_6

Canon EF 24-105mm f/4.0L IS

12/14/2007 08:24:19 AM · #20

Quick question in an old thread:

Under basic editing rules, if you use an adjustment layer for anything, hue/sat for example, can you mask the layer at all? I think not and I have a backup plan, but I would like to know without having to submit a file.

Mr_Pants

SiPix Blink

12/14/2007 08:34:12 AM · #21

Originally posted by Delta_6:

Doing that would constitute selective editing, which is not allowed under basic. Possible exception would perhaps be to add a completely grey mask to tone down the effect, although this could just as well be done by altering the adjustment layer's opacity.

Delta_6