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Archive 2012 · RGB Values; 3 & 252
  
 
frank gross
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p.1 #1 · p.1 #1 · RGB Values; 3 & 252


How best to achieve this (instructions from a stock agency):

RGB Values
RGB values should be limited with a black point of no less than 3 and white point of no more than 252. This
should be performed at the end of Photoshop editing. In doing this, extreme highlight and shadow detail will
retain all the information needed to print successfully. This also will limit the possibility of color banding and
clipping within the file.

Do I create a Curves adjustment layer and drag the top & bottom points to 3 & 252, or is there a better way to achieve the task?

Thanks,

Frank



Jan 16, 2012 at 09:05 PM
skibum5
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p.1 #2 · p.1 #2 · RGB Values; 3 & 252


frank gross wrote:
How best to achieve this (instructions from a stock agency):

RGB Values
RGB values should be limited with a black point of no less than 3 and white point of no more than 252. This
should be performed at the end of Photoshop editing. In doing this, extreme highlight and shadow detail will
retain all the information needed to print successfully. This also will limit the possibility of color banding and
clipping within the file.

Do I create a Curves adjustment layer and drag the top & bottom points to 3 & 252, or is there a better way to achieve the task?

Thanks,

Frank


You could instantly do it with the Adjustments->Levels tool, no need for nonsense with curves and layers.
Just keep input at 0 and 255 and change output levels to 3 and 252



Edited on Jan 16, 2012 at 09:59 PM · View previous versions



Jan 16, 2012 at 09:57 PM
frank gross
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p.1 #3 · p.1 #3 · RGB Values; 3 & 252


Thanks. I got the answr I need in another forum = Levels adjustment > output box numbers


Jan 16, 2012 at 09:58 PM
frank gross
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p.1 #4 · p.1 #4 · RGB Values; 3 & 252


And thanks skibum5 too


Jan 16, 2012 at 09:59 PM
Peter Figen
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p.1 #5 · p.1 #5 · RGB Values; 3 & 252


The Levels Output method would only work assuming your numbers are 0 and 255 for black and white. It's much better to use actual Curves and place Info Palette probes in the areas you want to monitor and set your endpoints with the Curves dialog. Then, at the same time, you can address everything else you want or need to with that tool.

Furthermore, no matter what the stock agency says, you probably do want to let specular highlights go to 255, and if there's black with no detail at all, it does no harm to let it go below 3. Actually, nothing below about 10 is going to print with any detail anyway and an RGB 253 is almost always going to convert to 1C, 1M, 1Y, 0K, which is barely the slightest of tone and certainly not discernible detail. More realistic number for detail are 10 and somewhere between 245-248.



Jan 17, 2012 at 12:04 AM
skibum5
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p.1 #6 · p.1 #6 · RGB Values; 3 & 252


Peter Figen wrote:
The Levels Output method would only work assuming your numbers are 0 and 255 for black and white.
It's much better to use actual Curves and place Info Palette probes in the areas you want to monitor and set your endpoints with the Curves dialog. Then, at the same time, you can address everything else you want or need to with that tool.


Why wouldn't it work regardless It just makes sure everything is somewhere within 3 and 252 even if it doesn't hit 3 or 252 necessarily.

And if you want to use different inputs and make sure 3 and 252 are hit or want something else accomplished then just measure and change 0 to 3 or 10 or 255 to 252 or 240 or whatever you want





Jan 17, 2012 at 02:04 AM
pjheller
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p.1 #7 · p.1 #7 · RGB Values; 3 & 252


Just set the eyedroppers in curves . . . set the white to 245, middle to 128 and black to somewhere between 10-20 (depending on your preference).


Jan 17, 2012 at 08:24 AM
Peter Figen
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p.1 #8 · p.1 #8 · RGB Values; 3 & 252


"Why wouldn't it work regardless It just makes sure everything is somewhere within 3 and 252 even if it doesn't hit 3 or 252 necessarily.

And if you want to use different inputs and make sure 3 and 252 are hit or want something else accomplished then just measure and change 0 to 3 or 10 or 255 to 252 or 240 or whatever you want"

Just setting the output setting in Levels to 3 and 252 doesn't make the highlights and shadows those numbers. What it does is move whatever your highlight number is down three notches and whatever your black point up three notches, so if you've got a black point of 4,5,3, it will end up at 7,8,6. You can't use the output sliders to make shadows darker or highlights lighter, only the other way around. Since there's no mention in the original post about whether or not this stock agency has specified the highlight number for specular highlights, that would create another problem. You usually want speculars to blow out to paper white, but bringing them down to 252 would only tone down the entire image, the opposite of what we're trying to do with print - y'know, maximize the impact of ink on paper.

While you can use the eyedroppers in Curves or Levels to set endpoints, it's almost always better to do it manually. You don't always want those numbers to be dead neutral, and very often you want to alter other points on the curve to maximize contrast or correct color casts or crossovers.

The funny thing about those numbers is that they're exactly the numbers I have locked into my drum scanner when I made the scanner profile from the HutchColor Velvia target. Those were the number that gave me just a tick of headroom on both ends, taking into account the conversion to working RGB. But to request those for stock photos doesn't make any sense at all.



Jan 17, 2012 at 08:57 AM
RustyBug
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p.1 #9 · p.1 #9 · RGB Values; 3 & 252


Peter Figen wrote:
so if you've got a black point of 4,5,3, it will end up at 7,8,6.


I would have thought that the output slider would have simply clipped the output, so that 4,5,3 would still remain 4,5,3 whereas 1,1,1 would have been clipped to 3,3,3. Does it really simply ADD/SUBTRACT rather than CLIP ?? (You can tell I don't use the output slider much.)


Yup, ADDS & SUBTRACTS ... go figure.
I never noticed since I use info pallette probes to watch as I adjust (curves or otherwise) ... like Peter suggests

Ran a series of 0,1,2,3,4,5,33 pure swatches, levels output @ 3 ... became 3,4,5,6,7,8,35
Ran a series of 252,249,246,243,240,222 levels output @ 248 ... became 245,242,239,236,234,216

Interesting to note (but likely insignificant) that @ 240,222 it only subtracted 6, and @ 33, it only added 2 (i.e. 1 less each).

So, if your image had a black @ 8, and you THOUGHT that using the output slider would clip the data, and you wanted an output of 12, setting the output slider @ 12 would actually yield 20, instead of the 12 that you were striving for. Setting the output slider to 4 (i.e. LESS THAN than your starting point of 8) would yield the 12 that you desired, i.e. Peter Figen wrote:
The Levels Output method would only work assuming your numbers are 0 and 255 for black and white.



EXCELLENT point Peter ... thanks.



Jan 17, 2012 at 09:06 AM
Peter Figen
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p.1 #10 · p.1 #10 · RGB Values; 3 & 252


Rusty - For years, literally, I was confused about why people recommended using the output sliders, and by people I really mean Bruce Fraser and the Real World Photoshop series going back to 1995 when I started reading them.

What I didn't understand then but do now, was, why you needed to set the output sliders to compensate for printing on paper when you had ALREADY set your pixel values as part of your tonal manipulation. Fraser and Blatner never explained that and left the same confusing examples in their books at least until the time I stopped reading them, which I think was around Ps7 (not CS7). I actually think that the advice to continue using the output sliders comes from so many people who read those books and were subsequently confused as well. There are plenty of other examples like that in those books. Thankfully, we now know better but still have to deal, like the original poster, with archaic, ill informed guidelines, often devised by people that just don't know any better but put in a position to enforce them nevertheless.



Jan 17, 2012 at 03:57 PM
 

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RustyBug
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p.1 #11 · p.1 #11 · RGB Values; 3 & 252


Personally, I'm not a big fan of some sliders ... but still use them with certain aspects. I'm a big fan of using the probes for the info pallette (numbers comfirmation). I just wish there were more than 4 available to use at one time ... like LR that has 9 or 10.

I'll typically use two or three of them to check any given aspect, 3 differing shadow areas, 3 differeing specular, white, WB, color cast areas, etc. I'd like to be able to keep more of them up all the time, so that as I start moving through PP I can keep tabs on everything. Instead, I have to move them around more than I'd like and lose track of things along the way, forgetting to 'double check' along the way when I get focused on some other aspect of PP.

Of course, PS has much more than just one way to accomplish just about everything, i.e. tools of choice for user preference. I'm still learning much and much to go, but am starting to get settled in after around two years of PS. Somedays, I feel like I've got pretty good command & control ... other days, I feel like it'll be decades before I ever "master" the silly thing.



Jan 17, 2012 at 04:15 PM
Peter Figen
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p.1 #12 · p.1 #12 · RGB Values; 3 & 252


Linocolor, the old Heidelberg scanning app had eight probes back in the mid 1990's, and even though I know Adobe has had requests for more for Photoshop, they seem to have resisted. While four is an inconvenience, it's not that big a deal to move them around as needed.


Jan 17, 2012 at 04:36 PM
frank gross
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p.1 #13 · p.1 #13 · RGB Values; 3 & 252


I'm losing you guys.I cant keep up...

In novice terms...

Assuming there are no specular highlights to be concerned about flattening to a dull 'grey'.
Would the 3 & 252 requirement be best achieved with Levels output numbers?



Jan 17, 2012 at 06:03 PM
Peter Figen
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p.1 #14 · p.1 #14 · RGB Values; 3 & 252


Frank,

I make a good part of my income setting up files for all sorts of output. If I were doing it, I would ignore the output levels part and just use your Info Palette to monitor your pixel values. You can shoot for highlight with detail values of approximately 245-250 and shadow with detail of about 10-15. There is some room for subjective decisions there. If you want real detail in the highlights, err more toward 245 or maybe down to 240. It all depends on the image and what mood you're going for. On the shadow end, pretty much everything below 10 is going to print black anyway. A black point of 3 is, for all practical purposes, going to look identical to one of zero or five. If you push it to zero, it is possible to, at the same time pull a 13 down a few notches and lose some of the near black detail. Again, subjective, and depending on how it's going to be used, you may want to go one way or the other. For stock images, I would think you're better off being a tad conservative and letting whoever is buying the images make the final adjustment.



Jan 17, 2012 at 06:16 PM
RustyBug
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p.1 #15 · p.1 #15 · RGB Values; 3 & 252


Not a big deal ... just would like to be able set up my workspace with a few more, that's all ... maybe CS6 will provide for better workspace customization.


Jan 17, 2012 at 06:55 PM
skibum5
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p.1 #16 · p.1 #16 · RGB Values; 3 & 252


Peter Figen wrote:
"Why wouldn't it work regardless It just makes sure everything is somewhere within 3 and 252 even if it doesn't hit 3 or 252 necessarily.

And if you want to use different inputs and make sure 3 and 252 are hit or want something else accomplished then just measure and change 0 to 3 or 10 or 255 to 252 or 240 or whatever you want"

Just setting the output setting in Levels to 3 and 252 doesn't make the highlights and shadows those numbers. What it does is move whatever your highlight number is down three notches and whatever your
...Show more

As I said it makes sure that everything is somewhere between 3 and 252 even if it doesn't necessarily hit 3 or 252.

And as I also said if you do want the boundaries of the output to hit 3 and 252 then you could ask for the darkest and brightest and say it is 8 and 240 and then you simply enter 8 and 240 for input and 3 and 252 as output.


You can't use the output sliders to make shadows darker or highlights lighter, only the other way around.


No, but you can use the input sliders to do that and levels also has input sliders.

As for curves, maybe you want some altered roll-off rather than a quick levels adjustment, that depends, sometimes you might prefer that and sometimes you don't want it at all or the difference isn't enough to care even if you do and levels is fast and easy.

Since there's no mention in the original post about whether or not this stock agency has specified the highlight number for specular highlights, that would create another problem. You usually want speculars to blow out to paper white, but bringing them down to 252 would only tone down the entire image, the opposite of what we're trying to do with print - y'know, maximize the impact of ink on paper.


This is a very good point, if you preserve them too much you can end up with my print is too dark or it looks a bit to flat, dull, etc. I definitely don't disagree with this in any way at all.



Jan 17, 2012 at 07:23 PM
skibum5
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p.1 #17 · p.1 #17 · RGB Values; 3 & 252


RustyBug wrote:
I would have thought that the output slider would have simply clipped the output, so that 4,5,3 would still remain 4,5,3 whereas 1,1,1 would have been clipped to 3,3,3. Does it really simply ADD/SUBTRACT rather than CLIP ?? (You can tell I don't use the output slider much.)
:


No output slider can't clip, you are mixing up the input slider with the output slider.

Levels maps input range to output range.

The output slider sets the range for the output.

The input slider doesn't map the image to the input slider range since that would be redundant to what you can do with the output slider and provide no way to clip. The input slider clips off anything below its bottom setting and anything above its top setting.

Levels maps bottom of input to bottom of output and top of input to top of output.

So input is 0-255 and output is 0-255 nothing happens.

If input is 20,200 then any parts of the image below 20 or above 200 are clipped to 20 and 200 as you could verify if you set output range to match at 20 and 200 then the darkest tones are all 20 and the brightest are all 200.

If you set input 20,200 and output 0,255 then you end up with all of the original image at 20 or below set to black and anything in the original image at or above 200 set to white.

If you leave input at 0,255 and set output to 50,200 then you clip away nothing but reduce contrast and dynamic range and have the darkest parts look gray and the brightest parts look very dingy white.

etc.

You can use the midtones part of input to skew scaling away from balanced toward shadows or highlights.


(as for Bruce Fraser and so on I've never read any of his books or any of the other guides actually other than a few peeks here on there to find out a few things about masking or levels or how to make animated gifs or how to slide images from layer to layer and the LAB space sharpening thing back before smart sharpen)



Jan 17, 2012 at 07:40 PM
frank gross
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p.1 #18 · p.1 #18 · RGB Values; 3 & 252


Peter Figen wrote:
Frank,
If I were doing it, I would ignore the output levels part and just use your Info Palette to monitor your pixel values. .


Peter,
Do mean simply by moving the cursor over the image & looking at the Info palette?
What is the suggested workflow? Do I have a Curves adj layer open at the same time and use the little 'hand icon' to click on and adjust the curve ?



Jan 17, 2012 at 08:05 PM
RustyBug
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p.1 #19 · p.1 #19 · RGB Values; 3 & 252


skibum5 wrote:
If you leave input at 0,255 and set output to 50,200 then you clip away nothing but reduce contrast and dynamic range and have the darkest parts look gray and the brightest parts look very dingy white.


i.e. 0+50=50 and 255-55=200

along with:
193 (25% gray) becomes 164
67 (75% gray) becomes 89



Jan 17, 2012 at 08:09 PM
Peter Figen
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p.1 #20 · p.1 #20 · RGB Values; 3 & 252


"Peter,
Do mean simply by moving the cursor over the image & looking at the Info palette?
What is the suggested workflow? Do I have a Curves adj layer open at the same time and use the little 'hand icon' to click on and adjust the curve ?"

Frank - I think the worst feature Adobe crammed into the new version was that horrible little "hand" - the TAT control or whatever it's called. It's okay for Hue/Saturation, but not at all appropriate for Curves.

When I open a Curves Adjustment Layer - and I do with using an F-Key Action in order to get the older dialog box which I find far superior, I first determine where I want to "probe", as it were, and use the Shift-click method to place probes in areas of interest. Another reason to access the older dialog box is that Adobe changed the shortcut for placing probes, which had not changed since I started using Ps. After place the probes, I'll open the individual Curves for the red, green and blue channels and use those to set the end points - neutral if that's what I want - or not if I want a cast. At the same time, you can address overall color, contrast and crossovers. You can either fix or induce crossover with Curves, but not with Levels. And often, you want to do one Curves move with the Adjustment Layer set to Luminosity blend and another to Normal or maybe Color. It's too easy using the master RGB curves to oversaturate unintentionally when set to Normal blend mode.

I never ever use the "hand". I always place adjustment points along the curve corresponding to the areas tonally that I want to affect. Remember that you can place up to 16 points on a given Curve and can use multiple points to help isolate areas and "lock down" others.



Jan 17, 2012 at 08:32 PM
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