Difference layer mask

[Boneappetit]

Originally Posted by julianmarsalis

Bone its not a mode its a mask your creating to just effect midtones with a curve layer lol key pt from Mr Randall is and then ask for a layer curve. Now you can play with adding or detracting density from the midtone area to help create the illusion of more density. Usually this is a darkening move, but it can go the other way too.


Its not a mode its a type of mask you use on a curves layer a difference mask >.>. I have the picture somewhere printed out lol...

Julian: I don't understand why you insist in something that is completely out of context... are you Mr. Randall's lawyer? My question is already answered, Jonas, Natalia, Murray and Flashtones already wrote the correct answer. The confusion comes because of the term "Difference Mask", relax man, it is not the end of the world, at least not yet, that's all. We are all learning here...

[julianmarsalis]

Originally Posted by Boneappetit

Julian: I don't understand why you insist in something that is completely out of context... are you Mr. Randall's lawyer? My question is already answered, Jonas, Natalia, Murray and Flashtones already wrote the correct answer. The confusion comes because of the term "Difference Mask", relax man, it is not the end of the world, at least not yet, that's all. We are all learning here...

lmao dude it doesnt get more relaxed then me it doesn't matter a bit at all I think you take what I am saying wrong so no biggie cool breeze....

[Flashtones]

Originally Posted by mistermonday

Hi Flashtones, what you have generated is known by me as a midtone mask. It can also be generated by Select>Color Range and select Mid Tones from the pull down menu.
To me a difference mask has always been a mask created to isolate fine differences between two almost identical layers and those differences are more often not in midtones. One example where I use it is to make a very precise selection using a Hue/Sat adj layer. A Hue/Sat adj can actually isolate certain pixels in a manner that can not be achieved with Selective Color or Magic Wand, or other tools. The problem is that Hue/Sat will not allow you to make a selection from the pixels that it is affecting. Setting the layer to Difference Blend mode and making a mask of the difference does the job.
Regards, Murray

Murray, what you describe can certainly be considered a difference mask, I just don't think it's what Mr Randall was describing and that Bone is in quest of. Randall was talking about increasing contrast and dimension via curves through finely controlled luminosity masks, with the difference mask set to target the midtones.

Edit: as I read above it appears that is not what Boneappetit is looking for and I really don't understand the context of the conversation. Oh well...

[Boneappetit]

Misc. note: Difference Blend Mode can also be used with the blur filter and a couple of steps more to boost colors of a flat looking image...

[julianmarsalis]

Originally Posted by Flashtones

Murray, what you describe can certainly be considered a difference mask, I just don't think it's what Mr Randall was describing and that Bone is in quest of. Randall was talking about increasing contrast and dimension via curves through finely controlled luminosity masks, with the difference mask set to target the midtones.

Edit: as I read above it appears that is not what Boneappetit is looking for and I really don't understand the context of the conversation. Oh well...

Ditto flash but what you showed is exactly what I need tho and appears to be exactly what Mr Randall is discussing thanks again Julian

[Flashtones]

Originally Posted by julianmarsalis

Ditto flesh but what you showed is exactly what I need tho and appears to be exactly what Mr Randall is discussing thanks again Julian

I think so too. If one tries my method vs Color Range > Midtones they'll see exactly the more nuanced mask that he mentions.

[Boneappetit]

Originally Posted by Flashtones

Murray, what you describe can certainly be considered a difference mask, I just don't think it's what Mr Randall was describing and that Bone is in quest of. Randall was talking about increasing contrast and dimension via curves through finely controlled luminosity masks, with the difference mask set to target the midtones.

Edit: as I read above it appears that is not what Boneappetit is looking for and I really don't understand the context of the conversation. Oh well...

Yes Flash, it is exactly what I was looking for... As I wrote earlier, the confusion comes over the term "Difference Mask", some call it that, that's ok. That feature only comes with After Effects, what some call DM it's a luminosity mask along with a Diff Blend mode... As I told Natalia, the way I see it is that After Effects uses this because it is an animation program, there I can understand the "use of a difference mask", but not in Ps. The important thing here is the result of using this process... and I already have it... I didn't think my question was going to get this complicated, and even more after I got what i wanted, hehe...

[Flashtones]

Originally Posted by Boneappetit

Yes Flash, it is exactly what I was looking for... As I wrote earlier, the confusion comes over the term "Difference Mask", some call it that, that's ok. That feature only comes with After Effects, what some call DM it's a luminosity mask along with a Diff Blend mode... As I told Natalia, the way I see it is that After Effects uses this because it is an animation program, there I can understand the "use of a difference mask", but not in Ps. The important thing here is the result of using this process... and I already have it... I didn't think my question was going to get this complicated, and even more after I got what i wanted, hehe...

I'm glad it worked out.

[Aladdin]

I will stick to solving world hunger.

@Boneappetit: Thank you so much.

[Boneappetit]

Originally Posted by Aladdin

I will stick to solving world hunger.

@Boneappetit: Thank you so much.

No problem mate, that's the good part of all this, we can all learn...

[Eikon]

Originally Posted by Flashtones

One can be made without calculations as such.
Go to the channels pallet and CMD+Click the composite channel to select the luminosity.
Hit the new channel button at the bottom of the pallet to create an alpha channel based on this luminosity.
Select the new channel to make it active. The original Luminosity selection should still be active, and now fill that selection with black.

I wa reading the same dave hill thread with the missing mr.randall links and went in search of how to create a difference mask. The above appeared to be the solution but i couldnt get it to work. So let me see if i have this right...

First off, unless im a damn fool, im cs5, ctrl clicking selects the layer contents, not the luminosity. Apparently to do that, the new shortcut is ctrl+alt+2.

With that selected, clicking the new channel button gives me black, not a luminosity based alpha. To create a new channel based on this selection you must either...
a) ctrl click the new channel button & invert that new map, or...
b) select -> save selection, create new channel

With that done, and the original lumi selection still marching, filling that selection with black doesnt work... At least not via the paint bucket. You can press delete to bring up the fill option and select black, and that will fill with black properly.

This apparently finally gives you the magical differnce map... Cept, is it? Its a black and grey map, no white... Is this what we want? If you open up levels on this new channel you see all the info is over on the left. If we drag the white slider over to the edge of color range, the we get a full white black and shades of grey map. But again, is this what we want? Using this "full range" version as a curves mask will give different results than using the original black and grey version.

So thats my question... Just wondering which is the INTENDED way to use the difference map.

Thanks all.

[John Wheeler]

Hi Eikon

As always, my posts are all just IMHO.

In reading the whole thread, the search for the Holy Grail of the Difference Mask was much like a solution in search of a problem.

Sometimes it is much easier to describe what you would like to achieve (as was eventually done in the thread) and come up with ways to achieve a solution to that problem.

From my best understanding (because it jumped around a bit) this was in search of a midtone mask. You are correct that the approach mentioned in the thread that you repeating in your post does not have a mask that reaches all the way up to white. So if you want an adjustment Layer to be able to have full effect that Layer Mask created as you indicated would have to be adjusted.

Murray indicated an much easier way to create a midtone mask and that was with the Color Range tool and selecting midtones. All of the neutral color tones in the Color Range are based on Luminosity. Once the selection is made it can be converted directly as a Layer Mask or saved as a Channel. If this Mask/Channel does not transition as desired it is a simple change with a Levels or Curves adjustment.

IMHO there was a lot of focus on Robert Randall's difference mask approach. From all that I have read about Robert Randall his approach is more along the lines of having an image, knowing what he wants to change, and then with a deep understanding of how all the different Photoshop tools, blends, etc he uses (or invents on the fly) the approach that achieves what he intends to change. It may sound subtle yet I think it is significant. He is "what do I need to change" centric vs "what can this tool do for me centric."

Everyone has an approach that best works for them and if you want a midtones adjustment mask (which I think is the bottom line of the thread) then Murray's approach is the easiest without having to create extra channels, selections, adjustments, calculations, or angst. Hope this was helpful.

[Eikon]

i gotcha john. not saying i was trying to be rob randal or anything. i was just reading a thread which lead me to the question of whats a difference mask, and how can i make one. i use highlight and shadow masks all the time, but since the process flashtones outlined didnt work, that got me MORE determined to figure out what it was and how to make it.

and ya, i realized you could do it with color range, but think i also read something like 'you get better, more subtle results if you do it this way'. so i wanted to create the mask both ways and see which was better.

anyway, ya it was helpful. ultimately i was not looking for someone to handhold me in PS. iv been doing it long enough and usualy know how to get the look im after. its just something id never heard about and figured there was an opportunity to learn!

thanks for the insight.

[John Wheeler]

Hi Eikon
No intention to imply anything about robbing. Just trying to point out I think the difficulty of finding documentation on Randall's difference mask approach increased the anticipation of value as if it were the Holy Grail (I. Obviously did not communicate well).

You duplicated the technique in the thread and got the same result that I also observed. I create difference masks an alternate way and for a different purpose. If interested I could add that to the thread as well.

[Eikon]

sure john... might as well! the more methods the merrier.

[Flashtones]

Originally Posted by Eikon

I wa reading the same dave hill thread with the missing mr.randall links and went in search of how to create a difference mask. The above appeared to be the solution but i couldnt get it to work. So let me see if i have this right...

First off, unless im a damn fool, im cs5, ctrl clicking selects the layer contents, not the luminosity. Apparently to do that, the new shortcut is ctrl+alt+2.

With that selected, clicking the new channel button gives me black, not a luminosity based alpha. To create a new channel based on this selection you must either...
a) ctrl click the new channel button & invert that new map, or...
b) select -> save selection, create new channel

With that done, and the original lumi selection still marching, filling that selection with black doesnt work... At least not via the paint bucket. You can press delete to bring up the fill option and select black, and that will fill with black properly.

This apparently finally gives you the magical differnce map... Cept, is it? Its a black and grey map, no white... Is this what we want? If you open up levels on this new channel you see all the info is over on the left. If we drag the white slider over to the edge of color range, the we get a full white black and shades of grey map. But again, is this what we want? Using this "full range" version as a curves mask will give different results than using the original black and grey version.

So thats my question... Just wondering which is the INTENDED way to use the difference map.

Thanks all.

Not sure what the problem is. I'm using CS5 on a mac and my steps work as stated. CMD+Clicking the composite RGB channel is exactly the same as CMD+OPT+2.

Sorry I can't explain why it works on my system and not yours. Maybe you could pose the question on the Adobe board, but I suspect you are doing something wrong. Are you sure you're clicking on channels and not layers?

Anyway, ultimately a mask of blacks and grays is fine; that's the subtlety, that was noted, in play. If your adjustments through that mask aren't strong enough just duplicate the adjustment layer as many times as needed for added strength. Or, adjust the mask with levels, etc, to suit your needs.

[Eikon]

Not to worriec about it. Maybe its a pc thing? I dont recall if i tried it with clicking the rgb channel, or just the layer. I probably tried it both ways since i read your description over and over and over to try and figure out why it wasnt working as described.

Anyway no prob. We all get there eventually!

[John Wheeler]

Hi Eikon

Per our previous discussion, following is the images and mask used where the key ingredient in creating the mask was using the difference mode blend. I did this in a post about 6 months ago in another forum. I received permission to post the original image on RTP from its author Shawn Rakestraw at http://www.pixelrake.com/

Here is the original image:
Original.jpg

Here is the mask that I created using blend mode as a key ingredient:
Difference-Mask.jpg

Using that mask I replace the background as an example:
Replaced-Background.jpg

And here is the image and just using some adjustment layers with the mask:
Modify-Just-Sky.jpg

Here is the copy and paste from the other forum on the steps I took:

I usually make up the masking approach on an image by image basis and on the fly - enjoy the experimenting. I usually think in terms of how can I make the image parts I don't want black and the parts I do whan white. I wanted to get rid of the blues and the bright white clouds. Soooo
1) To make blue black
Stamped image; foreground to sampled blue sky; ;pencil tool to difference mode and painted one continuous stripe over area ~ horizon and above
2) Make White clouds black
Stamped another original image; foreground to sampled white clouds; pencil tool in difference mode and painted one continuous strip over area ~horizon and above; used curves adj layer (levels would work too) and moved white point for right balance with tree and snow on tree (won't be perfect)
3a) Combine 1 and 2 with blend (I used screen yet others work too)
3b) Used B&W adj layer to tweak the image to get right balance
4) Threshold to max just make black and white
5) Use "0" tolerance and Quick selection tool to pick up a few pieces of tree snow not picked up by above (I typically have a zero tolerance policy in regards to the Quick Selection Tool
6) Magic wand to give selection
7) Use intersection of this selection with all area above horizon
8) Move selection to mask
9) Use refine mask to add 1 px feather
-------------------------------------------------------
Difference mode blend was used in combination with several other approaches to create the mask I desired. Hope this is useful and thanks again to Shawn to use his original image.

[Chain]

Original question has been solved (make a mask of the mid-tones). Discussion is venturing into interesting masks that can be made based on the results of the Difference blend mode -*perhaps worthy of it's own (less confusing) thread?

Just jumping in here to request that we stop using the confusing term "difference mask" (it explains nothing) and call it "mid-tone mask" or whatever is most explanatory. Or just "mask".

To me, the term "difference mask" could be applied to any mask that has been created as the difference between two layers. It doesn't specify what the mask actually is so I find it only serves to confuse.

[unimatrix001]

I understand that this thread has been solved but i found this awhile back from a photography site thought it might help clarify this question for new readers.
http://internet-retards.com/wpmu/pho...t-photography/

[Chain]

Nice little link related to using the difference between two layers/images as a mask; could just use a couple of example images.

The link refers to what I have encountered as difference keying in video. To summarize you take two almost identical photographs (or video sequences) – one with the object, and one without – and use the difference as a mask (or at least a starting point).

[Eikon]

john, thanks for the blurb but i didnt quite follow it, sorry i find it quite hard to read instructions and get whats going on. im better at watching instructions or doing then... ive always learned better that way. bottom line, as long as you get the mask/selection you want...EHHH! everyone wins. especially you.

[skoobey]

1. I've read the whole theme, so please don't make me read it again.

2. What has been discussed is mostly product photography, landscapes and background clean up-s.

What I intend to do is USING A DIFFERENCE BLENDING MODE on a MERGED LAYER of all the healing for example (merging the split and the separate healing into one layer) to MAKE a MASK of all the differences in order to achieve a simple on/off effect as if that the split wasn't there in the first place.

This kind of masking would only be effective if done with high level of precision and would HELP LOWER THE SIZE OF THE IMAGE FILE CONSIDERABLY especially if you are using multiple splits and split-related layers.

[Eikon]

skoobey, i dont think this is the type of difference they were refering to, but if it works for you, keep on trucking.

does skoobey refer to skoobey do? or do you own a subaru?.... that wasnt meant to rhyme, its a serious question.

[skoobey]

OK, HERE GOES.

Save the file as a backup in case something goes wrong.
Merge all the layers you wish to be affected by mask.
Set merged layer at difference blending mode.
Reset your swatches by pressing D.
Select>Color range at 0 Fuzziness.
Click the mask icon holding the Alt/Option key.
Set the layer blending mode back to normal.
Now you right-click the mask icon and chose Apply mask if you wish to apply the mask, or alt+click on the mask to see the differences between the layers more clearly.

P.S. It is what it is, lol, my nickname has no particular meaning.

Also, I think I explained it rather well here, even if you dont apply the mask, it sure is easier to NOTICE things on a MASK itself rather then searching through a dark and gloomy difference mode.

+ You don't have to merge anything, but grouping those layers instead and then seting the groups blending mode to Difference, and then doing everything as I told you. I mean, experiment with it, THIS IS JUST A PRINCIPLE TO GET A MASK OUT of a DIFFERENCE MODE.