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Who uses curves?

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OK, I have a question

Ive gone through a couple basic tutorials by now on curves and setting the shadows and highlights, and Im confused on which levels for RGB to use.

For example, on the "popping" tutorial on Dgrin (a forum with smugmug) the poster sugessts 7 7 7 for black and 247 247 247 for white(rgb) and in Scott Kelby's CS2 book for Digital Photographers he suggests 20 20 20 for black and 244 244 244 for white. I understand they are different shots ( a portrait and a colorful lights at a carnival) but how do you when to change the values? The pop articles says to default those settings. Should you always use the same values for black and white when setting your points?
I hope someone can explain this. (and dumb it down as best you can)Thanks

Oh, and unrelated, but for lab, can I change back to rgb when im done with pp?

--
http://provethesunshine.smugmug.com/
http://shudderrelease.blogspot.com/
 
It has long been argued that those settings are incorrect because they don't exploit the full gamut of the monitor. And unless you're specifically preparing photos for printing there's no need to modify the black and white clipping points as in your example.

See this thread; especially the contributions by Thomas Niemann: http://forums.dpreview.com/forums/read.asp?forum=1006&message=25629602

Or better yet, go to his site at http://www.epaperpress.com/psphoto/index.html and click on Color Correction > Black/White and see what he has to say.

If I'm not mistaken some of the more recent Photoshop book like Photoshop CS3 Studio Techniques by Ben Willmore omit this advice on remapping clipping points.
fretsonfire said:
OK, I have a question
Ive gone through a couple basic tutorials by now on curves and
setting the shadows and highlights, and Im confused on which levels
for RGB to use.
For example, on the "popping" tutorial on Dgrin (a forum with
smugmug) the poster sugessts 7 7 7 for black and 247 247 247 for
white(rgb) and in Scott Kelby's CS2 book for Digital Photographers he
suggests 20 20 20 for black and 244 244 244 for white. I understand
they are different shots ( a portrait and a colorful lights at a
carnival) but how do you when to change the values? The pop articles
says to default those settings. Should you always use the same values
for black and white when setting your points?
I hope someone can explain this. (and dumb it down as best you
can)Thanks

Oh, and unrelated, but for lab, can I change back to rgb when im done
with pp?

--
http://provethesunshine.smugmug.com/
http://shudderrelease.blogspot.com/
Click to expand...
 
Thank you, Babine, Suddie and Kent -- I've been thinking I need to expand my curves "techniques."
 
fretsonfire said:
So you dont even set the shadows (blacks) and highlights (whites) ?
Isnt that how you get curves to use the full tonal range?
Uuugh, and I thought I had it figured out...
Please let me know. What you said goes against most of what ive learned.
Click to expand...
"Some image editing habits become so ingrained that it is hard to unlearn them when newer ways come along and make the old favorite methods redundant. An example of this is the subject of setting the output Levels in Photoshop for the print output. For many years Photoshop users were taught to set the output levels for the shadows at a slightly higher value than 0,0,0, even though (as you will read here) it has not been necessary to do so for quite some years now."

http://photoshopnews.com/2008/01/14/camera-raw-and-the-shadow-output-levels/

--
Kent

http://www.pbase.com/kentc
tutorial archive:
http://porg.4t.com/KentC.html
 
I think there may be two different issues under discussion here.

In curves, when you set a highlight point and shadow point, you select the brightest and darkest 'significant' areas -- those regions that you want to show at least some detail.

255,255,255 and 0,0,0 won't show any detail. So, you if you decide that some highlight and some shadow ought to show at least some detail, then you use curves to set those areas as almost while and almost black, but not quite. Everything brighter and darker will be blown or plugged: but this is OK, because those areas don't contain significant detail.

Which values you use to show significant detail is dependent on your output device. Ansel Adams' Zone System divided the output range into 11 zones, with zone 0 being black and zone X being pure white. He recommended placing the most significant dark tones in zone II and the most significant light tones in zone VII. In RGB values this translates the dark as 46 to 67, and the white from 185 to 207. Computer monitors do quite a bit better than this, so most folks recommend placing the most significant dark and light values closer to 0 and 255. However, I would think that printers still have a narrower range, but I don't know.
 
No, I don't alter the default settings in Photoshop.

Kent, thanks for that link to the Martin Evening article. I don't recall seeing it before.
fretsonfire said:
So you dont even set the shadows (blacks) and highlights (whites) ?
Isnt that how you get curves to use the full tonal range?
Uuugh, and I thought I had it figured out...
Please let me know. What you said goes against most of what ive learned.

--
http://provethesunshine.smugmug.com/
http://shudderrelease.blogspot.com/
Click to expand...
 
I DO! I DO!

Very useful tool.

For some basic curves info - go to google video and type in "photoshop curves".

DAWF
 
OK, can someone clarify.

Is setting the the shadows and highlights necessary for making the image better overall? It seems like theres mixed comments here. Is it something that I should try to do to all my images to maximize tones, or should I just use curves to say find the highlights and shadows in a bug or a face and mess with them how I want to with an s curve, etc. (the more you dumb it down, the better)
--
http://provethesunshine.smugmug.com/
http://shudderrelease.blogspot.com/
 
suddie,
suddie1215 said:
Kent, thanks for that link to the Martin Evening article. I don't
recall seeing it before.
Click to expand...
Welcome. Black Point Compensation was added in PS 5.0:

http://partners.adobe.com/public/developer/en/pdf/AdobeBPC.pdf
http://www.digitaldog.net/files/Black_Point_Compensation.pdf

... and as noted that has to be checked in your settings... well, check out this discussion:

http://www.outbackphoto.com/tforum/viewtopic.php?TopicID=2134

--
Kent

http://www.pbase.com/kentc
tutorial archive:
http://porg.4t.com/KentC.html
 
Can you explain what that is and how/ why I do it? Sorry for all the questions, if you're sick of my stupidity, just let me know :)

But I really really really appreciate all this help! Im overwhelmed with helpful information. It just seems suddenly its all clashing. Through all the articles I'ce read, it seemed to me that one of the most important, crucial actions in curves is to set the black and white points...and I had that down pat! :( I was excited that I was finally getting it. haha. now that isnt even needed...hmm...ill get it eventually.
--
http://provethesunshine.smugmug.com/
http://shudderrelease.blogspot.com/
 
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