jjbong
Jan-10-2011, 08:37 PM
One of the PPW tools is what Dan Margulis calls False Profile and Multiply through a Mask, and
pathfinder suggested a providing description and example of this.
It is intended for images that have two very distinct sections, one light and one dark,
like my shot of the Coloseum in a different thread:
185327
But it can also be used with images that have a much less extreme issue of the same
sort, like this image of Villa Torlonia, a lovely villa outside of the walls of
Rome (that Mussolini appropriated as his residence):
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249/1152006087_FoHAu-XL.jpg
It doesn't look so terribly bad, But the interesting parts of the image are quite dark, and
there is an interesting part of the image on the right that is much darker than the rest of the image.
I'll use this as an example for the technique.
Dan discusses False Profiles in Chapter 15 of Professional Photoshop 5th edition, but
has not documented the False Profile/Multiply through a Mask technique in his books,
as the PPW postdates the latest book. I looked through the threads on his book in Dgrin
for a discussion of Chapter 15, but I couldn't find any. I found a few references to using
them, but not much else.
The use of False Profiles is based on an insight on how to achieve certain results, and
a specific way to do this in PS. Unfortunately, the concept of False Profiles is difficult
to understand, and both the creation and use of them is fraught with opportunites to
make mistakes. Fortunately, it turns out that there's another, much easier way to do
exactly the same thing. This was discovered by others exploring the PPW, and I've seen
some posts from Dan saying that he does it himself in certain cases. So I'll not talk at all
about False Profiles, and instead discuss the simpler, equivalent mechanism.
The core idea is very simple. You have an image like the Villa, where you want to
lighten part of it and at the same time not lose the contrast in the lighter parts. First you
lighten the entire image, taking care not to blow out any part of it. Then you
darken what were the light parts, without darkening too much what were the dark parts.
The first part you do by changing the image's gamma, the second by multiplying the
result through a mask.
Note that I am using PS CS3. In later versions, the user interface may vary somewhat.
Beginning in PS CS3, you have the ability to change the gamma of an image. You do
Image->Adjustments->Exposure and you get this dialog:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Gamma/1152018563_QEZM9-O.jpg
You adjust the gamma by moving the slider to the left to lighten the image, and to the
right to darken it. You don't have to know anything about what gamma actually is or
what the numbers represent. Just play with the slider to get the effect you want.
Unlike more standard ways of lightening the image, adjusting the gamma will do so without
blowing out the highlights.
For this image, for example, I adjusted the gamma by 1.4, with this result.
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-After-Gamma/1152018484_29sKR-XL.jpg
If you understand what gamma is, note that I am not setting the gamma to 1.4, but
adjusting it by 1.4, whatever that means to PS (I haven't found exact documentation
for it; I have read posts that claim that it's a relative adjustment, i.e., multiplicative
to the current workspace gamma).
The whole image is lighter, and nothing is blown out. Of course, the original light
parts don't have the contrast they did, but that's for the multiply step.
You duplicate the background layer, set the mode to Multiply, and then duplicate the
top layer again. On some images, you will do this multiple times. Then you merge all of
the multiply layers down into a single layer. Here we'll use just two multiply layers
(layers before the merge):
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Layers-1/1151994131_ZYvvJ-O.jpg
This is what you get:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-Multiply-no-Mask/1152016979_GMC2x-XL.jpg
Pretty awful, at this point. We have restored contrast to the highlights, but the rest
of the image is worse than where we started. What we want to do is get the lightening effect
of the gamma change in the darker parts of the image and the effect of the additional multiply into the
lighter parts of the image. The way we do this is with a layer mask. We want a mask that's
light in the light parts of the image and dark in the dark parts. That's not hard at all to
build, as probably each of the individual R, G, and B channels have this characteristic, as
does the composite RGB channel. So we just have to pick out the best one.
Merging the multiply layers, and adding a layer mask:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Layers-2/1151994223_c86Lo-O.jpg
Set the layer mask using the Image->Apply Image (when you add the layer mask,
the layer mask itself is automatically selected, so that's where the Apply Image target is).
You have 8 choices for a layer mask in RGB:
each of the R, G, and B channels and the composite RGB, and you can select either the
Background layer or the Merged layer. Since the Background layer is lighter than the Merged
layer, using one of its channels will result in a darker image overall (since the mask will
be relatively light everywhere, allowing the multiply in the top layer more effect). Conversely,
using a channel from the Merged layer will result in a lighter image overall.
You can cycle through these choices in the Apply Image dialog and select the best one. Here,
I chose composite RGB from the Background layer, as I liked the sky better and I knew I could
improve the villa. But you could go in the opposite direction and choose the composite RGB
channel from the Merged layer and use other techniques to get a better contrast in the sky.
As is usually the case with masks, you want to blur them. For this technique, a pretty big
blur (30px or so) usually works well, although I've found cases where it generates
unacceptable halos. Here, I applied a Guassian Blur, 30 px. to get this:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-After-Multiply/1152008861_CVmAP-XL.jpg
It isn't finished, but it's a much better base for the standard techniques than the
original. The shadows are lighter, and there's still good detail in the mid-tones and
highlights.
That's bascially it. You use the gamma slider to lighten the image, you choose how
many layers to multiply, you choose a channel for the layer mask (from 8 choices),
and you blur. This becomes the base image for your normal workflow.
Using the rest of the PPW, I ended up with this:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-Final/1152017492_5TM4F-XL.jpg
I am happy to provide the missing steps, but the point of the post was the gamma
change/multiply through mask technique, so I'm omitting the rest of it for now.
pathfinder suggested a providing description and example of this.
It is intended for images that have two very distinct sections, one light and one dark,
like my shot of the Coloseum in a different thread:
185327
But it can also be used with images that have a much less extreme issue of the same
sort, like this image of Villa Torlonia, a lovely villa outside of the walls of
Rome (that Mussolini appropriated as his residence):
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249/1152006087_FoHAu-XL.jpg
It doesn't look so terribly bad, But the interesting parts of the image are quite dark, and
there is an interesting part of the image on the right that is much darker than the rest of the image.
I'll use this as an example for the technique.
Dan discusses False Profiles in Chapter 15 of Professional Photoshop 5th edition, but
has not documented the False Profile/Multiply through a Mask technique in his books,
as the PPW postdates the latest book. I looked through the threads on his book in Dgrin
for a discussion of Chapter 15, but I couldn't find any. I found a few references to using
them, but not much else.
The use of False Profiles is based on an insight on how to achieve certain results, and
a specific way to do this in PS. Unfortunately, the concept of False Profiles is difficult
to understand, and both the creation and use of them is fraught with opportunites to
make mistakes. Fortunately, it turns out that there's another, much easier way to do
exactly the same thing. This was discovered by others exploring the PPW, and I've seen
some posts from Dan saying that he does it himself in certain cases. So I'll not talk at all
about False Profiles, and instead discuss the simpler, equivalent mechanism.
The core idea is very simple. You have an image like the Villa, where you want to
lighten part of it and at the same time not lose the contrast in the lighter parts. First you
lighten the entire image, taking care not to blow out any part of it. Then you
darken what were the light parts, without darkening too much what were the dark parts.
The first part you do by changing the image's gamma, the second by multiplying the
result through a mask.
Note that I am using PS CS3. In later versions, the user interface may vary somewhat.
Beginning in PS CS3, you have the ability to change the gamma of an image. You do
Image->Adjustments->Exposure and you get this dialog:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Gamma/1152018563_QEZM9-O.jpg
You adjust the gamma by moving the slider to the left to lighten the image, and to the
right to darken it. You don't have to know anything about what gamma actually is or
what the numbers represent. Just play with the slider to get the effect you want.
Unlike more standard ways of lightening the image, adjusting the gamma will do so without
blowing out the highlights.
For this image, for example, I adjusted the gamma by 1.4, with this result.
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-After-Gamma/1152018484_29sKR-XL.jpg
If you understand what gamma is, note that I am not setting the gamma to 1.4, but
adjusting it by 1.4, whatever that means to PS (I haven't found exact documentation
for it; I have read posts that claim that it's a relative adjustment, i.e., multiplicative
to the current workspace gamma).
The whole image is lighter, and nothing is blown out. Of course, the original light
parts don't have the contrast they did, but that's for the multiply step.
You duplicate the background layer, set the mode to Multiply, and then duplicate the
top layer again. On some images, you will do this multiple times. Then you merge all of
the multiply layers down into a single layer. Here we'll use just two multiply layers
(layers before the merge):
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Layers-1/1151994131_ZYvvJ-O.jpg
This is what you get:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-Multiply-no-Mask/1152016979_GMC2x-XL.jpg
Pretty awful, at this point. We have restored contrast to the highlights, but the rest
of the image is worse than where we started. What we want to do is get the lightening effect
of the gamma change in the darker parts of the image and the effect of the additional multiply into the
lighter parts of the image. The way we do this is with a layer mask. We want a mask that's
light in the light parts of the image and dark in the dark parts. That's not hard at all to
build, as probably each of the individual R, G, and B channels have this characteristic, as
does the composite RGB channel. So we just have to pick out the best one.
Merging the multiply layers, and adding a layer mask:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/Layers-2/1151994223_c86Lo-O.jpg
Set the layer mask using the Image->Apply Image (when you add the layer mask,
the layer mask itself is automatically selected, so that's where the Apply Image target is).
You have 8 choices for a layer mask in RGB:
each of the R, G, and B channels and the composite RGB, and you can select either the
Background layer or the Merged layer. Since the Background layer is lighter than the Merged
layer, using one of its channels will result in a darker image overall (since the mask will
be relatively light everywhere, allowing the multiply in the top layer more effect). Conversely,
using a channel from the Merged layer will result in a lighter image overall.
You can cycle through these choices in the Apply Image dialog and select the best one. Here,
I chose composite RGB from the Background layer, as I liked the sky better and I knew I could
improve the villa. But you could go in the opposite direction and choose the composite RGB
channel from the Merged layer and use other techniques to get a better contrast in the sky.
As is usually the case with masks, you want to blur them. For this technique, a pretty big
blur (30px or so) usually works well, although I've found cases where it generates
unacceptable halos. Here, I applied a Guassian Blur, 30 px. to get this:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-After-Multiply/1152008861_CVmAP-XL.jpg
It isn't finished, but it's a much better base for the standard techniques than the
original. The shadows are lighter, and there's still good detail in the mid-tones and
highlights.
That's bascially it. You use the gamma slider to lighten the image, you choose how
many layers to multiply, you choose a channel for the layer mask (from 8 choices),
and you blur. This becomes the base image for your normal workflow.
Using the rest of the PPW, I ended up with this:
http://jjbong.smugmug.com/Photo-Work/Dgrin-Grad-School/MG3249-Final/1152017492_5TM4F-XL.jpg
I am happy to provide the missing steps, but the point of the post was the gamma
change/multiply through mask technique, so I'm omitting the rest of it for now.