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DPChallenge Forums >> Hardware and Software >> 3 basic editing layer questions
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 10/02/2005 05:02:33 AM · #1
About this time last year my monitor got too dark to calibrate -- then died. I managed to get a second-hand replacement as payment for helping a friend set up a home network -- but the guns don't align properly, giving strange color tints at odd places and making every image look like it is over sharpened.

But, last week I (finally) bought a new monitor. To celebrate I joined the Critique Club (just did my first) and have been voting again. Working a lot of mandatory overtime allowed me to get the monitor, but it hasn't permitted too much free time to enjoy it. I did manage to get 20% in 'Rule of 3rds' -- but I spent most of that time playing with the 'interesting' entries in PS. As I vote I drag the images that catch my attention into PS and see what I would have done differently. I've learned a lot, just in this last week, but I've also acquired a few questions about PS layers and legalities under the Basic rules.

Question 1:
Is there a way to force a layer to reference the pixels of a specific layer -- and not the cummulative modifications of all layers below it. For instance, assume these layers:

4: Levels adjustment layer for Highlights
3: Levels adjustment layer for Midtones
2: Levels adjustment layer for Shadows
1: Original untouched Background layer

As it is:
- Layer 2 will reference the pixel values of the Background layer,
- Layer 3 will reference the pixel values of the Background layer modified by Layer 2,
- and Layer 4 will reference the pixel value of the Background layer modified by layers 2 and 3.

Is there a way to make layers 2-4 each reference the pixels of the Background layer? I know I could place each of Layers 2-4 each in a group with a copy of the background layer -- but, duplicating the Background layer for each makes for large files. That, and I was hoping to keep this Basic challenge legal.

Looking thru the PS help files I found the concept of Linking layers. While the description sounded promising, "... linked layers retain their relationship until you unlink them" -- but it should have read, "... the contents of linked layers retain their relationship until you unlink them" as it seems to only affect the on-canvas relationship of the layer contents and not the relationship of the layers to each other.

Question 2:
The rule on layers states: ... Only Adjustment Layers (or the non-Photoshop equivalent) may be used. ... Adjustment Layers must be applied in Normal mode. ...

Simply stated, are Groups of layers legal? This does lead to additional questions though. The default Blending mode of a group is 'Pass Through', not 'Normal'. 'Normal' is an option, however selecting it causes the group as a whole to be treated as an individual layer -- while 'Pass Through' treats the layers as if they were all inline and the grouping didn't exist.

A group set to 'Pass Through' isn't affecting the image at all, and is simply an organizational convenience -- so I would quess using a group in this manner is Basic editing legal. However, when set to 'Normal' the group itself becomes an image modifying layer -- but is not actually an Adjustment layer. So would groups be legal under the Basic editing rules with 'Pass Through' and 'Normal' blending modes?

Question 3
This question involves the 'Blend if...' option in the Blending Options dialog box. While this is a blending option, it is not a blending method anymore than opacity is. This allows the blending of the layer to be restricted to only certain tones or channels -- and while restricting modifications by pixel location (with selections or masks) has never been allowed, restricting modifications to specific tones or hues always has been.

I feel this option is in agreement with the existing enforcement of the Basic editing rules, and allows the use of techniques that duplicate the affect of some of the newer features of PS (such as Shadows/Highlights) which have been ruled as legal -- without requiring the latest versions of PS, or even using PS for that matter as this option is available in other editing programs (such as PSP) where Shadow/Highlights is not.

I should also note that I asked Manic this 3rd question in a PM last night. His view is that it would not be legal. I want to stress that my bringing it up here afterwards is not intended to challenge or disrespect his viewpoint in anyway. I just figured while I was asking questions, I may as well get a few more views on this as well.

Thank you.
David
 10/02/2005 05:58:04 AM · #2
Originally posted by Britannica:

Question 1:
Is there a way to force a layer to reference the pixels of a specific layer -- and not the cummulative modifications of all layers below it. For instance, assume these layers:

4: Levels adjustment layer for Highlights
3: Levels adjustment layer for Midtones
2: Levels adjustment layer for Shadows
1: Original untouched Background layer

As it is:
- Layer 2 will reference the pixel values of the Background layer,
- Layer 3 will reference the pixel values of the Background layer modified by Layer 2,
- and Layer 4 will reference the pixel value of the Background layer modified by layers 2 and 3.

Is there a way to make layers 2-4 each reference the pixels of the Background layer? I know I could place each of Layers 2-4 each in a group with a copy of the background layer -- but, duplicating the Background layer for each makes for large files. That, and I was hoping to keep this Basic challenge legal.

David


I don't believe this is true. I believe all 3 new layers are each referencing the pixels of the BG layer. Each layer is sending a set of instructions to a certain set of pixels in the BG layer.

For the rest of it, I have raised similar questions in the past about the internal logic of allowing certain kinds of layers and not other kinds, and it seems that the bottom line is they want to keep basic editing rules very simple on the surface. The further we go into cherry-picking certain actions, modes, whatever and making them "legal", the more complex it gets. The simplest possible ruleset (as far as layers go) would we be "no layers". Since they've allowed "adjustment layers" they've restricted all layers to normal blending mode to keep things simple.

Such simplicity can lead to some internal apparent contradictions; you have pointed out one, another would be allowing the use of "edit/fade effect" but not allowing duplicate layer from BG with effect on it and faded. I'm willing to accept that the SC posioon makes sense; once you start tweaking allowability, it spirals into major nitpicking and it gets hard to enforce.

R.
 10/02/2005 07:40:57 AM · #3
Originally posted by bear_music:
... I believe all 3 new layers are each referencing the pixels of the BG layer. Each layer is sending a set of instructions to a certain set of pixels in the BG layer. ...

You certainly have more experience with PS than I, but a simple experimnet illustrates each layer is accessing the end result of all visible layers under it. Create an arrangement to compress the dynamic range with two levels adjustment layers, one named Shadows (to lighten the image) and the other named Highlights (to darken the image. If it were true that both adjust from the background layer directly, it would not matter what order these layers were in. But, even with the 'Blend if...' option to limit the range of tones affected, the lower layer of the two will change the value of pixels to be within the affected area of the upper one. Dragging the layers to change their order while watching the image and the histogram shows the order does indeed matter -- and matters because a layer affects the combined result of all visible layers below it.

Originally posted by bear_music:
... For the rest of it, I have raised similar questions in the past about the internal logic of allowing certain kinds of layers and not other kinds, and it seems that the bottom line is they want to keep basic editing rules very simple on the surface. The further we go into cherry-picking certain actions, modes, whatever and making them "legal", the more complex it gets. The simplest possible ruleset (as far as layers go) would we be "no layers". Since they've allowed "adjustment layers" they've restricted all layers to normal blending mode to keep things simple.

Such simplicity can lead to some internal apparent contradictions; you have pointed out one, another would be allowing the use of "edit/fade effect" but not allowing duplicate layer from BG with effect on it and faded. I'm willing to accept that the SC posioon makes sense; once you start tweaking allowability, it spirals into major nitpicking and it gets hard to enforce.

R.

I agree, which is why I and several others have advocated moving away from the tool-based rule set we currently have. Such a system of rules always seems to move either toward more complexity as more and more tools are introduced or toward more inconsistency as the rules are kept simple.

The guideline I referenced above is a good example of this. As it stands, the guideline "selection by pixels is bad, selection by tone or hue is good" is the 'unwritten' guideline the tool-based rules are evaluated against -- I think it would make more sense to have that guideline as the rule and the usages of specific tools as the interpretation. Not only would it make the rules less complex, but a lot easer to understand -- not to mention increasing the accuracy of predicting rulings. Working toward a consistency in implementation seems s step in the right direction -- complex rules can be simplified (such as the above), but inconsistencies are harmful to the game as a whole.

I too am quite willing to accept whatever rules are handed down as the best for the community as a whole -- it is after all, their game. ;)

Incidently, it was your comments in recent threads (combined with playing around with images while voting) that led to these questions. You've mentioned looking for a Basic rule legal method of duplicating the dynamic range adjustments possible with the Ctrl-Alt-~ screen/multiply technique. These three questions were the result of having this question in the back of my mind while looking over the images.

David
 10/02/2005 09:07:59 PM · #4
Anyone with answers? ...comments? ...insults? ...anyone?

David
 10/02/2005 10:20:07 PM · #5
In a stack of adjustment layers, the top layer is affecting the BG pixels as modified by the active layers below it.

Try toggling some of the lower layers on and off to check the result.
 10/02/2005 10:27:42 PM · #6
David,
If you are trying to use more than one levels adjustment layer, you will definitely have issues with their interaction. A better alternative would be to use curves. Much of what can be done on multiple levels layers can be done more effectively on one curves layer. It's also a little easier to use more than one curves layer, since you can limit the tones that a curves adjustment affects by the area of the curve you manipulate. Overall, curves is a much more powerful tool than levels, and is quite intuitive once you get the hang of it.
Multiple adjustment layers are still legal in basic, but duplication of the base layer is not, even if all copies are the same. Just the way the rules are written.
10/03/2005 07:02:00 AM · #7
Originally posted by GeneralE:
In a stack of adjustment layers, the top layer is affecting the BG pixels as modified by the active layers below it.

Try toggling some of the lower layers on and off to check the result.

Originally posted by kirbic:
David,
If you are trying to use more than one levels adjustment layer, you will definitely have issues with their interaction. ...

Thank you both for your responses.

This is as I understood layers to work -- starting with the original, each layer changes the state of the image and passes it on to the next -- I was curious if there was a way to force a non-linear dependancy between the layers. After searching the help files and the internet to no avail -- I've concluded it is likely not possible. While doing so would allow for some specific relationships (such as the one I described) without the significant increase in PSD file size duplicating the background layer has -- but it would do so at the expense of greater complexity in dealing with layers that out-weight the gain, so I won't miss the functionality.

That takes care of question #1, and further experimentation has made question #2 irrelevant. While it is true selecting a blending mode other than 'Pass Through' causes the group to be treated as if it was a pixel layer -- it must have a pixel layer within the group for this to be true. Selecting anything other than 'Pass Through' for a group with nothing but adjustment layers in it results in the group having no effect on the image -- in other words, it turns the layers within the group off. Since the Basic editing rules only allow adjustment layers, it doesn't matter in the slightest what mode the group is set at; if 'Pass Through' the adjustement layers within the group behave as they would if they were outside the group and any other setting turns them off. This leaves just question #3.

Originally posted by kirbic:
... A better alternative would be to use curves. Much of what can be done on multiple levels layers can be done more effectively on one curves layer. ... Overall, curves is a much more powerful tool than levels, and is quite intuitive once you get the hang of it. ...

Curves is powerful -- no doubt about that -- combining most other adjustment tools into one, it can do most anything the others can. However, that is also it's greatest liability as all the other adjustments are changed at the same time. While I understand the operation of curves, I prefer the greater precision of breaking the editing steps into specific actions seperated as much as possible from the other adjustments to be made. There are some things curves does best -- but I have to disagree that basic distribution of pixels on the histogram is one of them. There may come a time when my knowledge of how the various adjustments interrelate with each other is great enough to be comfortable adjusting all of them at once -- but I doubt I will use curves even then for anything other than what only it can do. Keeping the process clean, clear and 'novice' readable is just too deeply instilled.

Originally posted by kirbic:
... It's also a little easier to use more than one curves layer, since you can limit the tones that a curves adjustment affects by the area of the curve you manipulate. ...

This is exactly the position I was stating earlier regarding question #3, thanks for illustrating it. Curves allows for selectively effecting only certain areas of the tonal range, as does the Shadow/Highlights, Color Balance, Selective Color and others I'm not thinking of at the moment -- all of which have been ruled legal under basic editing due to the interpretation that tonal selections are legal and pixel selections are not.

I am merely curious of how a ruling will go regarding the ability that allows for the same selective application of adjustments based on tone. The 'Blend if...' option does this -- and is much less PS-dependant than specific tools such as Shadow/Highlights.

As Bear mentioned earlier regarding his quest; although my sense of order and fair play grates at inconsistencies, I am willing to abide by either decision. But which will it be -- greater consistency of interpretation and application of the rules or maintaining the simplicity of the rules?

Originally posted by kirbic:
... Multiple adjustment layers are still legal in basic, but duplication of the base layer is not, even if all copies are the same. Just the way the rules are written.

This is as I understood it to be, no questions here -- thanks for the comfirmation.

David
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