Making masks for people

SG
Posted By
Scottie_G.
May 12, 2005
Views
433
Replies
10
Status
Closed
In Katrin E’s book, she talks of using dodge and burn to help with mask, but I’m wondering why? Why not just black and white with brush?

And on the really difficult hair, she says it is better to insinuate a transition, instead of drawing in every hair. Sounds great, just don’t know what that means to do. thanks!
Related Tags
mask

Must-have mockup pack for every graphic designer 🔥🔥🔥

Easy-to-use drag-n-drop Photoshop scene creator with more than 2800 items.

GD
glen_deman
May 12, 2005
I believe she’s talking more about the edges of a mask. For example, if you had to isolate a furball, you would use the brush or just make a rough selection and fill the center in. For the edges though, you want to be able to color in just the whispy hairs but not have to zoom in all the way and use a tiny brush (which still wouldn’t look good). So, you can use the Burn tool set to Shadows, at low opacity, and just work the area over with broad strokes and it will only "work" on the hairs and not the background (assuming you already did some channel and levels voodoo to get the object semi separated). In the same way, you can use the Dodge tool set to highlights to clean up the surrounding areas that might have some grey specs.

You can also use the brush, set to Overlay, and use white or black and it will behave roughly the same way. It is more of a coarse effect, while the dodge/burn allows for more fine tuning (because you can choose to affect highlights, midtones, or shadows).

Best to explain with pictures. Say you have a Santa hat, and you want to isolate the white cotton area.

Blue Channel of a Santa Hat <http://www.mustangmods.com/data/8259/bluechannel.jpg>

If I use the Brush, black color, set to Overlay, you can see that it tends to darken the grey areas a little too much.

Using Brush set to Overlay on Black Background <http://www.mustangmods.com/data/8259/brush.jpg>

However, in this case, using the Burn Tool works better. It leaves the white and grey areas alone and just darkens the black areas.

Burn Tool, set to Shadows <http://www.mustangmods.com/data/8259/burn.jpg>

No painstaking small brush strokes needed here, just broadly went over the black areas.

I like to use the Brush/Overlay dealie with harder edged images.

On the second item, regarding hair, I think she’s just saying that it’s not worth going after every hair because the naked eye can’t see every strand anyway. To emphasize every hair would look unatural (much like you wouldn’t draw every eyelash when drawing a face, it just looks bad). There’s also the diminishing returns (is the pic really that much better because you got those 7 extra strands of hair).
SG
Scottie_G.
May 13, 2005
thanks Glen, nice info.
What I did not understand, is that your are masking, black, and white. and don’t you need those hairs to be one or the other? or not? you are saying they can be grey. and brushed over all at once, and they will go with the mask for the face.?
This was a weak part of the book.
D
deebs
May 13, 2005
Using a brush is more direct but also more dstruction and introduces pixels & data that were not present in the original

Using dodge & burn helps to tweak original data into black or into white but usually not into both
GD
glen_deman
May 14, 2005
Scottie – the mask for the hairs can be grey. Say you have some fly away hairs in the image; maybe it’s not possible to totally isolate them from the background. If you try to paint in the hair (paint in the mask, that is) with solid black, you will inevitably get some of the background to show through as well. You’d probably have to use a tiny brush to really get just the hair to show, but the result would be a very sharply defined hair, which the naked eye wouldn’t actually see and it will appear fake.

If you fake it though (which Katrin Eisman was talking about) and just make the hair fade away earlier than it actually does, you don’t have to worry about the background at all.
SG
Scottie_G.
May 15, 2005
thanks Glen:
that’s what I was wondering, that you really can’t paint them in, but then, if you paint grey, then wont the BG your are trying to get rid of show up in the future composite?

Have not gotten to the Extract tool yet, but I hope it’s better than the laborious manual technique here.
PC
Pierre_Courtejoie
May 15, 2005
The main point of masks is that you can have gradual opacity, not only black or white. A mask only made of Black or White will have sharp transitions, something that should be avoided in certain cases for realism. If you have a one pixel wide hair, you may want to have it partially opaque-or transparent.

Sometimes, one creates a mask out of a channel. At that point, the dodge and burn tools help to create the desired result.

Yes, sometimes you can paint with grey, it all depends of the image, the mask you want to create, the channels available, etc…

It is maybe the way you ask your questions, but it really sounds like you are afraid to open a picture, and try away when you are wondering something. Indeed, learning Photoshop can be a daunting task, but it can be so easier when you use your intuition.

Trust me, you’ll have more gratification, and reach a better understanding by fiddling, playing around, experimenting in Photoshop… Then ask questions when you are stuck, or something does not work.
D
deebs
May 15, 2005
I’m sure there is a tutorial on this – I know I have seen one other than Kath’s I mean.

Try www.russelbrown.com as first stop. Failing that try a google on Photoshop tutorials from wz2k

Have you tried a combination of channels to generate a grayscale mask? It seems that some Photoshop gurus recommend this as a good practise way to obtain masks for fine fly-away hair n stuff like that…
DM
dave_milbut
May 15, 2005
Have you tried a combination of channels to generate a grayscale mask?

that’s a good point deebs, ol’ bean! 🙂
SG
Scottie_G.
May 16, 2005
No, just making notes here. Can barely achieve what’s in that book. Any other great books on compositing? This has to be about the most complex thing in PHotoshop, no?
D
deebs
May 16, 2005
Only to begin with

IMHO try to see the wood for the trees.

The steps may be complicated but the desired effect is quite simple really: a mask that retains fine edges as typified by fine fly-away hair.

Remembering, of course, that any grayscale image or its inverse can be used as a mask

I keep meaning to try a thresholded grayscale as a trial thingy from a grayscale image to see what that does.

How to Improve Photoshop Performance

Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

Related Discussion Topics

Nice and short text about related topics in discussion sections