Extract filter output as a layer mask

it'd be real handy if the Extract filter could provide its output as a layer mask instead of erasing the original layer. this would provide the user the option of applying the mask, and more importantly, it would preserve the original image on the layer allowing the user to edit the mask using the standard tools.
can this be done?

The engineers explained that this would not be possible due to the color edge decontamination that extract makes.

If you really want to do it, duplicate your layer, apply extract, CTRL+click on the layer thumbnail, then select the original layer and click on the layer mask icon.

ah.. sorry for bringing up old news. i searched for "extract" and "mask" and found nothing. i thought of the Ctrl+click method after sleeping on the problem, and i'm glad to see you suggest it too. it will server my purposes nicely.

i don't fully follow the explanation of why it can't be done. the filter is changing the color and the transparency of the pixels. can't it just change the transparency via a layer mask? if it's changing the color of the pixels as well, that's no big deal. that can be done as usual. i guess i'll just add this to the list of things that would be much easier if transparency could be manipulated like a color channel.

thanks.

I'm not an engineer, I have to trust them :D

I'm not an engineer, I have to trust them.




I'n not either, but I don't. Perhaps the code that they have written and modified over time does as you were told, and would need to be rewritten from scratch to provide this fuction.

So be it.

As it is I can copy a layer, run extract, then use that layer as a mask for the original. Finally I delete the copy that I extracted, giving the desired result.

This proves it is possible.

Yes, I gave that workaround in another thread made by Daniel, I think, but the enginner (was it Chris Cox?) said that doing so, it will negate the color edge contamination features of extract
(That I have an hard time to notice. Maybe for blue/green screen?).

It can't be rewritten to do that - you'd get bad results if you output it as a layer mask.

It is NOT possible to do what extract does and output a layer mask.

The color decontamination is a big part of what extract does (removing the background color from the foreground object).

The color decontamination is a big part of what extract does (removing
the background color from the foreground object).




Ah. That I understand, and agree that a mask won't cut it. Could it then be an option via a check box? Off, and the feature behaves as it does not. On, and it creates a mask, and disables the colour removal.

Sigh.

No, not really.

That would require a completely different masking tool.

the checkbox option would be fine, but it's easy enough to do the workaround as described manually.

not to be a pain about this, but i still don't understand what color decontamination has to do with transparency. a pixel has values for RGB and O (let's call it opacity). before applying Extract, all the pixels are completely opaque (100%). the filter then performs its magic, modifying the color of the edge pixels as well as their opacity. changing the RGB values of a pixel doesn't change its opacity just as changing the opacity of a pixel doesn't affect its RGB values. the filter does both, and they are independent. my question is: why is it impossible to separate the color change from the opacity change?

i'm not saying that the filter shouldn't perform color decontamination, it should. it should modify the colors of the pixels. however, it also changes the opacity of the pixels, and it would be nice if there was the option to do this via a layer mask instead of erasing the original (how about that checkbox?).

is this really impossible? the fact that i can perform the workaround and achieve identical opacity on the edges (though without the color decontamination) suggests that this is not only possible, but really easy.

Think about it....

The pixel starts out opaque, and it is a mix of the foreground object color and some fraction of background object color.

Decontamination is the removal of the background color (after creating some estimate of the fraction of foreground/background) -- leaving a foreground color that will composite correctly over any other color.

Unless you want hard edged masks (0 and 100% opacity only), you need the decontamination.

And the two need to go together to get a correct result.

um... you lost me. who said anything about doing away with decontamination?

i'm talking about AFTER the decontamination has been run. each edge pixel has been modified in color AND in opacity. all i'm advocating is using the new opacity values to create a layer mask (like the workaround), and restoring the pixels in the layer to full opacity.

the workaround does just this, but it applies the new opacity values to the original layer (without the color decontamination).

i guess this isn't that big a deal. it just makes more sense to me to edit things in a non-destructive fashion whenever possible. creating a mask always seems like a better choice than erasing pixels. especially since the user can always apply the mask and delete the pixels whenever they like.

i suppose, what i'd really like is the same control over pixel opacity as i have over RBG (or CMYK or LAB or whatever). right now Photoshop always feels incomplete whenever i'm working with opacity.

Ah, he wants direct opacity controls over pixels. A man after my own heart.

would it be worth it to start a new thread to request Opacity as a real channel or has it been covered enough in the past?

mmm... to make Adjustments on Opacity... makes my mouth water.

Chris, one thing to think about in regards to Extract is that the decontamination of pixels is ONLY worth it if the opacity matte of the Extract is perfect. And in my experience, the extract opacity is NEVER perfect ... I always have to go back and fix it once the filter is finished.

There's no good way to re-reveal what Extract has taken away ... so most people (like the posters here) ditch the color results of Extract and end up using just the opacity as a basis for a final mask.

What Extract is lacking in an abstract form is the ability SOMEHOW to touch up the opacity layer to make it perfect.

~Hanford