Difference layer mask

[Boneappetit]

I just want to know, how to create a Difference layer mask... maybe the correct term is Difference mask, i'm not sure...

[Godmother]

Explain the question. I don't understand

[Boneappetit]

I kinda suck explaining things, but I guess it is just a Difference mask, like when you do a Luminosity mask or shadow mask...

[Der_W]

Hm, use the "Image"-"Calculations", enter the channels you want to compare and choose "Difference" as the blending mode?

I'm not sure what you mean though, this is pretty much a guess ;-)

[Godmother]

Originally Posted by Boneappetit

I kinda suck explaining things, but I guess it is just a Difference mask, like when you do a Luminosity mask or shadow mask...

The blending mode difference will show different things with different layers.

I guess you can always do a stamp of what you get when blending, then selecting the luminosity of the RGB channel and creating a luminosity mask of the difference blending mode results - after that you get rid of all the steps, you could create an action that does it for you

Is that what u want?

x

[Boneappetit]

Natalia and Jonas, thanx a lot guys, I can pick a bit of what you both wrote, I guess that this "Difference mode" is not something we use too often in Ps... Perhaps my question is not the correct one, I know how to do a Luminosity mask, I just wrote that there as a comparison. What I meant was: Is there a process to create a "Difference Mask" or if the Difference blending mode could be used on a mask? The purpose is to "darken" things or create ambient density.

Natalia: Lo voy a escribir en Español para ver si me puedo explicar mejor... Solo quiero saber si el modo de fusion (Difference) puede usarse en una mascara, o si solo tiene el proposito de usarse como blending mode? Se que la pregunta es rara ya que no he visto a nadie utilizar un Difference Mask. El proposito es crear densidad en la foto, en el ambiente de la foto mas bien...

Thanx again guys...

[Boneappetit]

No worries guys, i just found an old thread on the same theme, very tricky thou... I will also check both of your advises. Thanx

http://www.retouchpro.com/forums/pho...ence-mask.html

[Boneappetit]

Originally Posted by Godmother

The blending mode difference will show different things with different layers.

I guess you can always do a stamp of what you get when blending, then selecting the luminosity of the RGB channel and creating a luminosity mask of the difference blending mode results - after that you get rid of all the steps, you could create an action that does it for you

Is that what u want?

x

Gracias una vez mas Natalia. Esto funciono perfectamente. Me faltaba la parte del Luminosity mask, lo trate y me gusto el resultado. Para ser honesto no entendia el difference mode, y lo estaba tratando de usar como cualquier otra mascara. Tambien aprendi que lo puedo usar de otras maneras en conjunto con el blur para crear otros efectos, etc. Creo que entendiste mi pregunta, mejor que yo mismo, jejeje...

[Godmother]

Originally Posted by Boneappetit

Gracias una vez mas Natalia. Esto funciono perfectamente. Me faltaba la parte del Luminosity mask, lo trate y me gusto el resultado. Para ser honesto no entendia el difference mode, y lo estaba tratando de usar como cualquier otra mascara. Tambien aprendi que lo puedo usar de otras maneras en conjunto con el blur para crear otros efectos, etc. Creo que entendiste mi pregunta, mejor que yo mismo, jejeje...

Leyendo el otro thread no encontre la utilidad para hacer esto.
Vos si?

x

[Boneappetit]

Originally Posted by Godmother

Leyendo el otro thread no encontre la utilidad para hacer esto.
Vos si?

x

Tampoco yo lo encontre, decidi hacer lo que me habias recomendado y funciono... El difference mask como tal solo se puede hacer en After Effects. En Photoshop se usa el Blend Mode de otras formas, con diferentes exposiciones, o con el blur filter... Si deseas puedes ver este video, el cual encontre muy interesante... http://www.youtube.com/watch?v=zolWLMHUd94

[Godmother]

Originally Posted by Boneappetit

Tampoco yo lo encontre, decidi hacer lo que me habias recomendado y funciono... El difference mask como tal solo se puede hacer en After Effects. En Photoshop se usa el Blend Mode de otras formas, con diferentes exposiciones, o con el blur filter... Si deseas puedes ver este video, el cual encontre muy interesante... http://www.youtube.com/watch?v=zolWLMHUd94

Si, yo uso el difference para visualizar al hacer coincidir limites... no entiendo el punto de usar una mascara hecha con esa diferencia, lo que seria la "difference mask"

entendes?

x

[Boneappetit]

Originally Posted by Godmother

Si, yo uso el difference para visualizar al hacer coincidir limites... no entiendo el punto de usar una mascara hecha con esa diferencia, lo que seria la "difference mask"

entendes?

x

Solo en estos ultimos dias he venido a entender "un poco el Difference Blend Mode", pero no lo de la mascara, ya que hasta donde yo recuerdo, nunca lo habia usado en mis trabajos. Solo hice la pregunta porque en un tutrorial lei el paso del Difference Mask para crear densidad en la foto. Algo como el trabajo que hiciste de diferentes modelos parados en un solar oscuro, en donde el ambiente de la composicion se ve denso, (de paso, muy buen trabajo).

Disculpa por poner a trabajar tu mente inecesariamente, por tus consejos tambien me he dado cuenta que no hace sentido el hacer ese DM, pero tampoco entiendo porque Adobe After Effect tiene esa funcion, supongo que es porque el programa es para hacer animaciones y pienso que en ese caso si puede tener efecto.

Me gusta hacer cosas diferentes siempre y busco como hacerlas y aprender de los mejores. De todas formas, tu consejo funciona. Gracias por tu ayuda, eres genial...

[Aladdin]

With due respect, can we have this in English so we all learn. Please.
@Boneappetit: If you get any thing out of this discussion, please feed us the goodies

[Boneappetit]

Originally Posted by Aladdin

With due respect, can we have this in English so we all learn. Please.
@Boneappetit: If you get any thing out of this discussion, please feed us the goodies

Hi Aladdin: My question was one out of not having knowledge on how to use the Difference Blend Mode, and I was trying to create a "difference mask" from it... Natalia and Jonas cleared that up for me... The difference blend mode, is used along with other features in Ps, like Luminosity Mask and Blur filter... besides, it is used with different exposures of the same shot. Basically i did this:
Quote:
The blending mode difference will show different things with different layers.

I guess you can always do a stamp of what you get when blending, then selecting the luminosity of the RGB channel and creating a luminosity mask of the difference blending mode results - after that you get rid of all the steps, you could create an action that does it for you. / ------

Actually it is a Luminosity mask with a Difference blend mode...

I came up with the question after I read this:
Quote:
Next make a difference mask like this…

http://www.robert-randall.com/MM/diff%20mask%201.jpg <---- Broken Link

Load it to make it active, 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. / ------

Perhaps Robert Randall meant something else, I don't know.
Difference mask is a feature that comes in Adobe After Effects not in Ps...
Natalia told me that she couldn't see the point on creating a mask from that difference. So that's about it...

I had to use Spanish with Natalia, so I could clearly communicate what I was trying to do...

Regards

[julianmarsalis]

Originally Posted by Boneappetit

Hi Aladdin: My question was one out of not having knowledge on how to use the Difference Blend Mode, and I was trying to create a "difference mask" from it... Natalia and Jonas cleared that up for me... The difference blend mode, is used along with other features in Ps, like Luminosity Mask and Blur filter... besides, it is used with different exposures of the same shot. Basically i did this:
Quote:
The blending mode difference will show different things with different layers.

I guess you can always do a stamp of what you get when blending, then selecting the luminosity of the RGB channel and creating a luminosity mask of the difference blending mode results - after that you get rid of all the steps, you could create an action that does it for you. / ------

Actually it is a Luminosity mask with a Difference blend mode...

I came up with the question after I read this:
Quote:
Next make a difference mask like this…

http://www.robert-randall.com/MM/diff%20mask%201.jpg <---- Broken Link

Load it to make it active, 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. / ------

Perhaps Robert Randall meant something else, I don't know.
Difference mask is a feature that comes in Adobe After Effects not in Ps...
Natalia told me that a "difference mask" makes no sense, and it really doesn't. So that's about it...

I had to use Spanish with Natalia, so I could clearly communicate what I was trying to do...

Regards

Robert Randall is a old master of photography who knows more about the subject then many peeps combined he was explaining exactly what his mask did in terms of the image and didn't cover its creation but if asked he would share maybe still would if asked. But I caveat he can be harsh but to be honest his work is pretty awesome and his knowledge of photography even moreso....

http://www.robert-randall.com/content/

Oh and I be very careful before I state something like his statement doesn't make sense be more like I don't understand how you made a or achieved a difference mask or you may get your ass handed to u lol...

[julianmarsalis]

Originally Posted by Robert Randall

Sometimes the difference mask can be a bit abrupt in transition of tone. When that happens, you can possibly overcome the effect by blurring one of the masks in your difference calculation.

a little more insight on the mask creation calculations baby...

Originally Posted by Robert Randall

When you stop to think of the number of different channels available for use in blending and calculations it's mind boggling. Most people think there are 10. RGB, CMYK, LAB, GS. I can make a huge amount of different channels from an assortment of color separations, as well as fabricating HSL channels through calculations. There are quite possibly hundreds of channels to choose from in making the assorted masks you might need. And yes, I use them all.

This thread is just full of Mr. Randall dropping knowledge people can't handle lol...

http://www.modelmayhem.com/po.php?th...=304298&page=1

[julianmarsalis]

Another interesting excert Mr Randall never answered but I am gonna try it myself:

Originally Posted by digital Artform

I assume you are taking a positive mask image and a negative mask image and using the Photoshop blend mode 'difference' to create these difference masks?

I played around a bit with that to see what it does. My guess is the difference blend mode turns a standard linear 45 degree rising tone curve into an inverted V-shape.

I have a suggestion that produces a soft curve into and out of the midtone difference mask.

http://www.digitalartform.com/archiv...s/outline1.jpg

http://www.digitalartform.com/archiv...s/outline2.jpg

Sometimes when I need what I think you are calling a difference mask I take a postive image and multiply it by its negative.

http://www.digitalartform.com/archiv...s/outline3.jpg

Anything that was black in either the positive or the negative goes black in the multiply, and what survives are the common grays.

http://www.digitalartform.com/archiv...s/outline4.jpg

The brightest gray is 25%, since it is the product of the 50% mid-grays in the input images, so you have to use a steep curve to crank final brightness by 400% to make it white.

http://www.digitalartform.com/archiv...ng_an_out.html

http://www.digitalartform.com/archiv...s/outline5.jpg

---------------

http://www.digitalartform.com/archiv...es/demoman.jpg

Here's my "outline" recipe in action in the movie Demolition Man (1993). I used black and white 3D turbulence to wipe this movie set from "normal" to "icy." All of the midtone gray areas in the wipe were extracted using the recipe described above and turned electric blue.

[julianmarsalis]

If its this simple someone slap me lol

If you copy one of the images to a new layer above the other,
change the mode to difference, duplicate the image, flatten layers and desaturate, this should give you a map of the difference between the images, where black is no difference,
that you can then use as a mask.

[mistermonday]

Originally Posted by julianmarsalis

If its this simple someone slap me lol

If you copy one of the images to a new layer above the other,
change the mode to difference, duplicate the image, flatten layers and desaturate, this should give you a map of the difference between the images, where black is no difference,
that you can then use as a mask.

Yes, that would work but wouldn't it be more efficient to just create a merge all layer and select the luminosity and hit the Create mask button?
Regards, Murray

[Boneappetit]

Originally Posted by julianmarsalis

Robert Randall is a old master of photography who knows more about the subject then many peeps combined he was explaining exactly what his mask did in terms of the image and didn't cover its creation but if asked he would share maybe still would if asked. But I caveat he can be harsh but to be honest his work is pretty awesome and his knowledge of photography even moreso....

http://www.robert-randall.com/content/

Oh and I be very careful before I state something like his statement doesn't make sense be more like I don't understand how you made a or achieved a difference mask or you may get your ass handed to u lol...

Hi Julian: There is no doubt in my mind that Mr. Randall is a super pro. But if you do a search on the internet about "Difference Mask in Photoshop" you won't find even a dot of info. not even on the Adobe page, and BTW that's why I asked. The only reference I've seen so far, is his own tutorial (the one you posted) but that link is dead, because he closed his MM account... I just said that "maybe he meant something else", I don't know...

Just want to clarify, I didn't say Robert Randall doesn't make any sense. For me and my very limited knowledge of Ps, it doesn't make sense, it is just not the purpose of the "D Blending Mode". I even wrote the question for him, then I changed my mind and didn't send it, because I thought, he won't bother to answer... So, if you find a tutorial on how to do it, please share it...

Correction: What Natalia told me was that she didn't see the point in doing a mask from Difference, the comment "makes no sense" is mine, reason written above. <---- bear in mind that Spanish is our main language...

[Flashtones]

I've not read all the links in this thread, and maybe I'm way off here, but I always thought of a difference mask as the difference between a luminosity mask and an inverted luminosity mask. IOW, a mid-tones mask.

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.

At that point the blacks of your alpha channel should be filled with black (upon creation of the alpha thru the luminosity selection,) and the whites should be filled with black too from filling the still active selection with black. What's left are your midtones - the difference between the luminosity mask and the inverted luminosity mask.

Adjustments made through this mask would primarily affect midtones.

But maybe I'm misinterpreting.

[Boneappetit]

Originally Posted by mistermonday

Yes, that would work but wouldn't it be more efficient to just create a merge all layer and select the luminosity and hit the Create mask button?
Regards, Murray

That's exactly my point Murray... Julian, I created an Action using these simple steps, just what Natalia posted earlier... So now I can see it is just a matter of how Mr. Randall calls that... No wonder why we cannot find any info. under the term "Difference Mask", it is just a Luminosity Mask under a Difference blend mode... Thanx for pointing this out Murray...

[Boneappetit]

Originally Posted by Flashtones

Adjustments made through this mask would primarily affect midtones.

But maybe I'm misinterpreting.

Darn right Flashtones, it affects midtones...

[julianmarsalis]

Originally Posted by Flashtones

I've not read all the links in this thread, and maybe I'm way off here, but I always thought of a difference mask as the difference between a luminosity mask and an inverted luminosity mask. IOW, a mid-tones mask.

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.

At that point the blacks of your alpha channel should be filled with black (upon creation of the alpha thru the luminosity selection,) and the whites should be filled with black too from filling the still active selection with black. What's left are your midtones - the difference between the luminosity mask and the inverted luminosity mask.

Adjustments made through this mask would primarily affect midtones.

But maybe I'm misinterpreting.

I think we may have a winner here basically it was for adjusting midtones.

Per Mr Randall

Load it to make it active, 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. / ------

Thanks Fleshtones that clears that up most excellent...

[Boneappetit]

Originally Posted by julianmarsalis

I think we may have a winner here basically it was for adjusting midtones.

Per Mr Randall

Load it to make it active, 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. / ------

Thanks Fleshtones that clears that up most excellent...

Julian: I think that's not the Difference Mode, that's more like the tangent mode, LOL...

[Flashtones]

Originally Posted by Boneappetit

That's exactly my point Murray... Julian, I created an Action using these simple steps, just what Natalia posted earlier... So now I can see it is just a matter of how Mr. Randall calls that... No wonder why we cannot find any info. under the term "Difference Mask", it is just a Luminosity Mask under a Difference blend mode... Thanx for pointing this out Murray...

But a stamped merge layer in difference mode over the file that created it would yield zero difference, or a fully black mask, no?

Which begs the question, what is the "difference" one is trying to find/effect?

I don't think the purpose it to find the difference between two images (to what effect?), it's to find an area of luminosity within one image.

[julianmarsalis]

Originally Posted by Boneappetit

Julian: I think that's not the Difference Mode, that's more like the tangent mode, LOL...

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...

[mistermonday]

Originally Posted by Flashtones

I've not read all the links in this thread, and maybe I'm way off here, but I always thought of a difference mask as the difference between a luminosity mask and an inverted luminosity mask. IOW, a mid-tones mask.

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.

At that point the blacks of your alpha channel should be filled with black (upon creation of the alpha thru the luminosity selection,) and the whites should be filled with black too from filling the still active selection with black. What's left are your midtones - the difference between the luminosity mask and the inverted luminosity mask.

Adjustments made through this mask would primarily affect midtones.

But maybe I'm misinterpreting.

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

[Boneappetit]

Originally Posted by Flashtones

But a stamped merge layer in difference mode over the file that created it would yield zero difference, or a fully black mask, no?

Which begs the question, what is the "difference" one is trying to find/effect?

I don't think the purpose it to find the difference between two images (to what effect?), it's to find an area of luminosity within one image.

Yes, if you apply the Difference Mode directly on the stamped layer, first we need to select the Luminosity mask, create it and then apply the DBM...

[julianmarsalis]

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

Robert talked about the limits of using select color...

Originally Posted by Robert Randall

Are you talking about using Color Range as a tool to create masks? You might find that creating masks by using apply several times in multiply gives you a smoother transition than a mask created using color range parameters.