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Photo Masks...

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Old 09-28-2002, 08:39 AM
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Rick Rick is offline
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Photo Masks...

hey all..I am trying to do something with a photo, and I figured turning the picture itself into a mask would be eaier.

I've tried several different ways to do it. I've looked for help all over the place, but I can't seem to find directions easy enough to follow.

I know it's possible, but maybe I'm just too dense to get it, or I'm looking for a complicated way of doing it, when it's easy.


The reason why I'm doing it is that I'd like to be able to easily change the backgrounds and/or make the face to show a pattern within it.

Thanks all,

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Old 09-28-2002, 10:14 AM
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winwintoo winwintoo is offline
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Rick, there are probably as many ways to make a mask as there are PhotoShop users but this is my favorite way when I want to change the background.

After opening the original image in PS, I make a copy of the original layer - I NEVER work on the original layer! Hide the original layer by clicking on it's eyeball.

On the copy layer, I add a layer mask by clicking on the layer mask icon at the bottom of the layer pallet.

With the layer mask selected and using the lasso tool, make a loose selection around the part of the image that you want to keep - don't get too close to the edges. Now reverse the selection - Selection > Inverse. Fill the selection with black. You will now be able to see the checkerboard which indicates that there is nothing there. Deselect.

Now using a soft round bruch, paint with black up to the edges of the image. If you paint over - and "erase" - part of the image that you wanted to keep, simply paint it with white and it will reappear.

When you're done, go to Layer>Remove Layer Mask>Apply

Now add a new layer with the new background and you're done.

Hint: I find the checkerboard hard to work on, so I usually put a layer filled with contrasting color under the image layer - it makes it easier to see what hasn't been painted out.

Hope this isn't too confusing,
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Old 09-28-2002, 10:31 PM
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jeaniesa jeaniesa is offline
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I think what you want to do is make what's called an "alpha channel". Margaret's solution works well and is easy when you have a well-defined subject. But I find when I have an intricate subject (such as tree branches/twigs), it is extremely time consuming to paint over each individual branch.

So, what I usually do (which may or may not be the easiest way) is look at each individual RGB channel (and sometimes the individual CMYK and/or Lab channels) to find the one that contains the most contrast between the subject (that I want to keep) and the background (that I want to replace). Once I find the channel I think has the most contrast, I drag the channel to the "new channel icon" at the bottom of the channels palette. I have now created an "alpha channel" (which can be loaded as a selection via Selection-Load selection...)

I usually need to do a little more work on the alpha channel to get it to the point where it makes a good selection for me however. The first thing I do is make sure the new channel is active, then run Edit->Adjust->Levels. I move the shadow and highlight sliders towards each other to get a good black and white mask (instead of the various shades of gray I invariably start out with. Often this will make some of the highlights in my subject/foreground turn white, which I don't want. So, I take a black brush and paint over any areas that I want to keep as my foreground. Depending on the subject, I might then run a slight Gaussian blur so that the selection edges are not too harsh. At this point, I may leave it as is or invert it - depending on my desired use. Remember that anything white in the alpha mask will be the area that is selected when you load the selection.

You will probably need to play around with the levels adjustment and the amount of blur you apply to the mask to get a good result, but I've used this technique quite successfully to isolate the pine needles of a pine tree (to my great relief!)

Good luck and please let me know if this is confusing in any way and I'll try to be more specific or explain it in a different way.


P.S. You might also want to look attutorial1 and tutorial2 which show the technique I describe above.
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Old 10-01-2002, 04:31 AM
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Flora Flora is offline
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Hi everybody!


Originally posted by Margaret
...there are probably as many ways to make a mask as there are PhotoShop users...
.....and I couldn't agree more!!! ... but when it comes to isolate a complex picture from its background I found this tutorial by Katrin Eismann to be the best!!

Sometimes I need to tweak this procedure by: desaturating, being less 'conservative' in the usage of the Levels, expanding or conctacting the selection a bit or by feathering other words, adjusting everything I can according to my necessities!...

It may not be the easiest nor the fastest way to mask an image...but the results are impressive!!

I attach an example of what I managed to do using this procedure....I left the wire at the bottom right of the image to show its accuracy....
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Old 10-01-2002, 07:40 AM
Stephen M Stephen M is offline
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A link to further links on masking and extraction:

A small article of mine on 'utility masks' - or common multi purpose Swiss army knife masking techniques:

Stephen Marsh.
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Old 10-01-2002, 10:02 AM
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Flora Flora is offline
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Hi Stephen!

Thank you very much for your precious links!!!!....And what an interesting and very useful article you wrote!!!

In Your article you mentioned the 'Custom Filter' as a way of masking.....I have started to 'fiddle' with it, (after reading Katrin Eismann book), as a way of sharpening as well.....any tip in helping me to better understand how it really works...and what all the 'squares' represent?
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