Layer Masks in Photoshop

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Itti

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Itti
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Could someone talk me through them please? What I want to do is to be able to create layer masks so that I can adjust the levels of a picture separately, for example darken the sky but not the foreground.

I have trawled through Photoshop's help but there are twenty different pages on layers, channels and masks and I can't quite find what I'm looking for.

What makes it worse is that I successfully did this a few days ago but I can't for the life of me remember how! I swear I've tried exactly the same stuff again!


Please include step by step breakdown! In particular do I want a quick mask or an alpha channel, and do I want to adjust levels as an adjustment layer or not? or do I want to make a new layer before I create the mask?


P.S. I use Photoshop 6.0.
 
You want to do everything as adjustment layers where possible. As it allows you to go back in and adjust the levels later if you need. But, without doubling your filesize as creating a whole new duplicate layer would.

When you create an adjustment layer (say for levels) it automatically comes with a layer mask attached. That's the white rectangle to the right of the levels symbol in your layers pallet.

To use the mask, there are a myriad of different ways, and which is best depends on the image, and what you're doing with it. Straightforward way is to click on the empty mask (the white rectangle) then select your brush and check it is set to black (hit "D" on your keyboard to set default colours, then "X" to toggle between black and white). Now you can 'paint' onto your image in black. Anywhere you paint black will block the adjustment layer, and show through the layer beneath without the levels adjustment applied. Paint white to bring the adjustment layer back, and change the opacity of your brush for graduating the transition.

Another way:

Put your levels adjustment layer on, then go to layers > layer mask > delete.

Now click back to your image underneath.

Now make your selection (with the magic wand or whatever) and if you want to touch it up by hand, hitting "Q" will put you in quick mask mode, now you can paint with your black and white brush to fine tune the selection. Red area is not selected, and what you see clearly is in your selection. Again play with the opacity of your brush for gradation. Hit "Q" again to return to normal work mode.

Now select your adjustment layer, and go back to Layers > Layer Mask > Reveal Selection (or Hide Selection depending on which way around you did it). This will give you a ready made mask based on that selection. You can go in to the mask and fine tune if need be, using the simple method above.

A very good way to fine tune tricky masks:

After you have a pretty good solid mask using whatever method you choose. Select the mask and go to Filter > Blur > Gaussian Blur. Apply a radius of 1 pixel, now go to Image > Adjustments > Levels, playing with the midpoint of your mask will allow you to control very finely, the transition areas of your mask, great for hair and other fiddly bits.

I've only ever used CS, CS2 and CS3, so apologise if this doesn't translate to 6.0.

Hope it's of some help though,

J.
 
You can adjust sections of an image using the selection tools such as the magic wand, lasso and rectangle. Make your selection, go into image > adjustments (I think?) and select what is appropriate. Levels and curves works very well for sky adjustments.

This can leave quite a harsh edge, so I would suggest making your selection and looking for the "Refine Edge" button on the top tool bar before making the adjustment. In the refine edge menu you should experiment with the feathering.

This method does not use layer masks! The undo method is your friend when things go wrong :)
 
Jayst84 said:
Which is why you always use adjustment layers. You can't undo if you save and then return to the file. Or if you do other stuff later, you can't change your mind about edits done earlier. :thumbs:
Click to expand...

If you process from RAW files then you dont have a problem because you will always have the original ;)
 
Thanks guys, especially Jayst. I will look over your instructions and the tutorials in more detail later when I have time to try them out but I have a couple of questions in the meantime.

If I've already made the selection (it's currently as a quick mask) can I use this in a layer mask or do I need to start from the beginning of one of the methods you described?

Also the way that I did it before definitely had the adjusting after the mask was in place, is there a way to do this? The trouble with making the adjustment first is that the histogram will display tones for the whole image instead of just the unmasked bit.
Also is there a way to adjust an adjustment layer once it's been done - I think so far I've only ever deleted the layer and redone it.
 
voodoochild said:
If you process from RAW files then you dont have a problem because you will always have the original ;)
Click to expand...

You can go back to the raw file, but that's a bit annoying if you've just spent 6 hours doing other editing to the file.

Itti said:
If I've already made the selection (it's currently as a quick mask) can I use this in a layer mask or do I need to start from the beginning of one of the methods you described?
Click to expand...

I may be missing what you're saying here, but I think that's the second part of what I said. If you have your quick mask, hit "Q" to come back out of it, so it's a regular selection, then make your adjustment layer. This will automatically apply the mask to reveal just the selection. Remember that you can save selections and load them whenever you like. (Select > Save Selection).

Your masks also go into the channels pallet, so you can go and grab them for other layers from there.

Itti said:
Also the way that I did it before definitely had the adjusting after the mask was in place, is there a way to do this? The trouble with making the adjustment first is that the histogram will display tones for the whole image instead of just the unmasked bit.
Also is there a way to adjust an adjustment layer once it's been done - I think so far I've only ever deleted the layer and redone it.
Click to expand...

Yep, if you make all your selections first then create your adjustment layer it will create the mask right away and just apply it to your selection.

To go back into an adjustment layer just double click on its icon in the layers pallet. There are only a few functions left that aren't useable as adjustment layers, such as shadow and highlight. To allow these to be editable you have to create smart filters, but that's a whole other story.
 
Thanks for the quick reply (gosh we're both up late). I really appreciate the help.
I will go through this when I'm not revising (hopefully I'll have some time tomorrow) and let you know if I have any problems. :)
 
Itti said:
Thanks for the quick reply (gosh we're both up late). I really appreciate the help.
I will go through this when I'm not revising (hopefully I'll have some time tomorrow) and let you know if I have any problems. :)
Click to expand...

No worries, I'm not that great at putting things into words, so you'll probably find a few things I missed out.

(It's only 2pm down here ;))
 
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