Layer Masks? - DPChallenge Forums

Nikon AF Nikkor 50mm f/1.8D

06/26/2006 11:44:56 PM · #1

What are Layer masks? What is their use?

_eug

Nikon D50

06/27/2006 12:30:41 AM · #2

Layer Masks are a good way of editing selective editing. It allows you to edit on a portion of the image while also being able to turn it on or off as well as being able to change options and even delete the layer and it's changes easily.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/27/2006 01:24:42 AM · #3

Originally posted by justin_hewlett:

Originally posted by stdavidson:
I airbrushed out in the layer mask the huge areas outside those specific places that were also affected by the curves adjustment, like the sky, but that I did not want changed.

Steve, can you please expound on this technique? It had never crossed my mind to use an airbrush on a layer mask to get a more natural feel, but I bet it works great. I would be interested in your procedure (brush size, opacity, etc).

Originally posted by stdavidson:

Oh, Justin... My son... let the almighty Wizard of Oz explain all wisdom... pay no attention to that little man behind the curtain!

There is nothing to it. This is standard stuff with adjustment layers. It is much harder to explain than to do but I will give it a shot.

Every adjustment layer has a layer mask, that usually empty white box on the right side of every adjustment layer you see in the layers pallet. That box determines what part of the effect from that layer is allowed to show through. When all white the effect over the whole image is allowed. If some places are made black then the effect is blocked and will not show through.

Click once on that box and it becomes highlighted. Then go to the tools pallet and make black your foreground color and select a brush. Then if you airbrush directly on the image you will block (or MASK) the effect from showing through everywhere you paint. Black will appear in the formerly all white box now in all the places you paint. Of course, depending on feathering and opacity settings you control the amount of black painted and what gets blocked.

It is as easy as that.

But here is the coolest part. If you make a mistake and block out too much or get sloppy you just switch the brush color to white and you can bring the effect back again. Then you can switch back and forth to paint white or black to make an effect show or hide. You will constantly change the brush size, feathering and opacity depending on your intended effect. Oooooo.... ahhhhhhh... gasp!

It is magic! And it is completely non-destructive!

You are not in Kansas anymore, my son!

Whoops, almost forgot to say... The great and powerful OZ has spoken!

Message edited by author 2006-06-27 01:26:06.

TransparentReality

Nikon D50

Nikon AF Zoom-Nikkor 28-105mm f/3.5-4.5D

06/27/2006 01:40:18 AM · #4

Layer masks have been some kind of revelation for me when I first learned how to use one properly a few months ago. I can't believe I've gone without this.

On a side note: Layer masks are permissible for adjustment layers in Basic Editing, right?

Tamron AF 28-80mm f/3.5-5.6 Aspherical for Canon

06/27/2006 02:41:08 AM · #5

Originally posted by _eug:

But non-destructive editting is also possible with Layers. Then what is so special about Layer mask?

KGregory

Canon EOS-300D Rebel

06/27/2006 02:52:30 AM · #6

Originally posted by TransparentReality:

My guess would be no - since you can't alter things selectively.

KGregory

Canon EOS-300D Rebel

Tamron AF 28-80mm f/3.5-5.6 Aspherical for Canon

06/27/2006 02:56:32 AM · #7

Originally posted by kbhatia1967:

Originally posted by _eug:
Layer Masks are a good way of editing selective editing. It allows you to edit on a portion of the image while also being able to turn it on or off as well as being able to change options and even delete the layer and it's changes easily.

But non-destructive editting is also possible with Layers. Then what is so special about Layer mask?

Layer masks are the greatest thing ever! By switiching back and forth between black and white brushes, you can reveal or hide details.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

06/27/2006 03:05:46 AM · #8

We're basically discussing non-destructive dodging and burning, people. It's a little more than that, but that's the upshot of it. And it's not legal in basic.

R.

yanko

Canon EOS-5D Mark II

Carl Zeiss 50mm ZE f/1.4 Planar T for Canon

06/27/2006 03:12:46 AM · #9

Originally posted by KGregory:

Layer masks are the greatest thing ever! By switiching back and forth between black and white brushes, you can reveal or hide details.

I use to think that but now I have moved on to the healing brush as the greatest thing since... layer masks. :P

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/27/2006 03:15:54 AM · #10

Originally posted by TransparentReality:

Wrong -- a Layer Mask functions exactly the same as a saved selection, mask or alpha channel.

Legal for Advanced, but not for Basic.

06/27/2006 03:16:53 AM · #11

Originally posted by KGregory:

Originally posted by kbhatia1967:

But non-destructive editting is also possible with Layers. Then what is so special about Layer mask?

Layer masks are the greatest thing ever! By switiching back and forth between black and white brushes, you can reveal or hide details.

But, this we can also do by switching ON/OFF the Layers?

06/27/2006 03:18:44 AM · #12

Is there any good tutorial to understand the concept of Layer masks?

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/27/2006 03:21:36 AM · #13

Originally posted by kbhatia1967:

Originally posted by KGregory:

Originally posted by kbhatia1967:

But non-destructive editting is also possible with Layers. Then what is so special about Layer mask?

Layer masks are the greatest thing ever! By switiching back and forth between black and white brushes, you can reveal or hide details.

But, this we can also do by switching ON/OFF the Layers?

With the brushes, you are hiding/revealing certain parts of the image to the effect of the adjustment layer.

The reason it's illegal in Basic is you are no longer applying the adjustment uniformly across the entire image; with a layer mask in place, and adjustment might have a little effect in this area, a marked effect in that area, and no effect over here in this corner.

Let me (or someone) make up some examples with screenshots ... maybe tomorrow ... the best examples I have are from a current entry.

Message edited by author 2006-06-27 03:22:39.

Mattel Barbie Photo Designer Digital Camera

06/27/2006 08:14:54 AM · #14

Originally posted by GeneralE:

Let me (or someone) make up some examples with screenshots ... maybe tomorrow ... the best examples I have are from a current entry.

I think, they will certainly be of help!

ChikaZAWa

Canon EF-S 18-55mm f/3.5-5.6

06/27/2006 08:22:02 AM · #15

Originally posted by yanko:

I use to think that but now I have moved on to the healing brush as the greatest thing since... layer masks. :P

What's the healing brush?

PhotoArt

Canon EOS-50D

Canon EF 24-105mm f/4.0L IS

06/27/2006 09:05:10 AM · #16

Thanks for the explanation.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/27/2006 01:57:52 PM · #17

I have to go to work soon, so this is in "outline" form" -- I will come back and fill in more text later ... (PS: or maybe not? It's more complete than I originally intended!)

This is an image of the eastern span of the Bay Bridge currently under construction. Naturally, for a brightly-sunlit day I set the WB to Tungsten, so now I need to get "arty" to see if there's a possibility of rescuing it, but it provides a fairly good model upon which to demonstrate.

RGB Curve Adjustmnent Layer for contrast. Note the white rectangle in the Layers Pallette indicates the curve applies uniformly to the entire image.

Hue/Sat Adjustment layer to change the color. I'm lousy at this, so I just did it enough to make a discernable, though not necessarily desirable, change.

Unfortunately, to make this, I had to have the masks layers already made, so you can (maybe) see that the effect is not applied to Yerba Buena Island.

See the shape in the Hue/Sat layer thumbnail? With the Hue/Sat Adjustment Layer selected in the Layers Pallette, you can go to the Channels Pallette, and select the channel for the Layer Mask. This layer is a separate 8-bit grayscale channel, meaning you can use and painting/drawing tools to fill or erase pixels. Gray pixels will represent partially-selected areas.

You have a choice as to whether the part you paint black is the area affected by the adjustment (selected) or protected from the effect (masked), and what color/transparency represents the channel when other channels are visible -- in this case, a 50% yellow color makes the mask contrast nicely with the blue BG. Note that this is a crudely-drawn mask -- if I really try and fix this, the mask will have to be carefully drawn to go between all the bridge girders and better follow the treeline.

Note that the name of the Layer Mask is in italics in the Channels Pallette. This means it only exists as an editable channel when the Adjustment Layer is the active channel. If you make the Background layer active, the Layer Mask disappears from the Channels list (more on this later).

A Layer Mask, an Alpha Channel, and a selection which has been saved (menu Select > Save Selection ...) are all essentially the same thing; a selection which can be re-loaded or modified at any time for repeated or adapted use.

Taking advantage of this, I made the Hue/Sat Adjustment Layer active and went to the menu Select > Load Selection ... and chose "Hue/Sat Transparency" from the pop-up list in the dialog box, as well as selecting off the Invert checkbox. This gave me a selection (marching ants) opposite of the original Hue/Sat area. When I then select New Adjustment Layer > Curves from the Layers Pallette, the selection becomes the Layer Mask for the effect automatically. I applied a Curve to the Blue Channel to try to return the Island foliage to a somewhat normal color, while leaving the rest of the photo blue.

Just to show how a "regular" mask is made, I now went to the Channels Pallette and selected New Channel, naming it for the Bank of America monolith near the center of the photo. Notice that the Curves Layer is still active, so its Layer Mask appears in the list of Channels, but its name is in italics, meaning it will "go away" once another layer is activated. By contrast, the BofA layer is in "regular" type, meaning it will remain as an editable channel no matter what layer is active (see next two images).

Note that to make it easier to see where to mask I made only the Green Channel of the image visible, and in this case I chose a red color to represent the mask and that the painted area represents the selected area.

Back in the Layers Pallette, I used the menu Select > Load Selection ... and chose the BofA Mask from the pop-up list. Then in the Layers Pallete I chose New Adjustment Layer > Curves and the active selection automatically became the Layer Mask for the Curves effect. A crude but obvious adjustment makes the building closer to the black monolith it really is.

Notice that in the Channels Pallette, both the BofA mask and the newly-created Curves Layer Mask exist, and the Layer Mask is the inverse in whether the color represents selected or masked -- I can only speculate on why they allow this inconsistency, and can't take the time now.

Once the last change is made and the BG Layer selected, all the Layer Masks disappear from the Channels Pallete (but remain available as long as the layer exists). The Alpha Channel can be kept or discarded (there's a "copy" in the Curves Layer!).

Message edited by author 2006-06-27 18:27:12.

yanko

Canon EOS-5D Mark II

Carl Zeiss 50mm ZE f/1.4 Planar T for Canon

06/27/2006 05:52:39 PM · #18

Originally posted by ChikaZAWa:

Originally posted by yanko:

I use to think that but now I have moved on to the healing brush as the greatest thing since... layer masks. :P

What's the healing brush?

It's a magical tool that allows you to paint in texture detail with a brush using other parts of the image or surrounding area as a source. It works great for what it does. I believe it was first added in CS and in CS2 they akso added the spot healing brush, which works similar.

Message edited by author 2006-06-27 17:55:07.

Canon EF 28-135mm f/3.5-5.6 IS USM

06/28/2006 12:29:41 AM · #19

Hi General,
I admire the effort put up by you. It will take quite some time for me to understand, but this is another story altogether.

I Enjoy Ham

Canon EOS-30D

06/28/2006 12:47:19 AM · #20

here yah go, konador once again is awesome with a tutorial on exactly what you want to know!

layer masks tutorial

scroll down and click on the layer mask tutorial..

-Dan

06/28/2006 08:14:17 AM · #21

I enjoyed the Video. But still failed to understand the real advantage of using a Layer mask (as compared to using duplicate layer, and erasing the unwanted areas).
Am I really a dumb?

Message edited by author 2006-06-28 08:16:37.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

06/28/2006 10:28:13 AM · #22

Here's a link to another series of articles on layers by Ron Bigelow.

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

06/28/2006 10:34:34 AM · #23

Originally posted by kbhatia1967:

I enjoyed the Video. But still failed to understand the real advantage of using a Layer mask (as compared to using duplicate layer, and erasing the unwanted areas).
Am I really a dumb?

If you use the layer mask, and later want to change what's revealed or hidden (masked) then you just change the mask. If you screwed up the mask entirely, you can start with a clean (white) mask.
If, on the other hand, you duplicated and erased, you can't "unerase" later, and so what you have is really destructive editing.
In short, the ability to tweak the mask, including using gradients or other gentle transitions, is a very powerful feature, and can save tons of time re-doing a layer that could have been just a tweak of a mask