Go to my blog www.craigstutorials.com/blog and scroll down to find the tut called "The Precise way to use levels to get great colors" and there you will find how to the exact spot for your white point or your dark point. My example is for Levels but it works for curves as well. Good Luck, Craig
Reference: Pop Tutorial – New & Improved (May 2004)
Question: What do you use as a white point when there’s no specific “white” in your image? (See my photo.)
Here's a way to do it with curves. The key is understanding what you want the "white point" to be in this picture. In DavidTo's tutorial, it's 247, 247, 247, or pretty much pure white. Here it obviously isn't. Using the Thresholds command described in the tutorial, the brightest point of interest is yellow in the flower. So you want the "white point" to be as bright a yellow as you can get. This means B=0 for sure. This particular yellow looks a little on the orange side, so we probably want R=247, and the only question is what G should be. I experimented until I liked what I saw (G=231). For the black point, it's easy, as the bee's body is the darkest spot and is indeed black. So we're aiming for R=G=B=5, or thereabouts. This is the curve I used to get there.
which produced this
Then you can extend the contrast enhancement technique in the tutorial by curving the R, G, and B separately. The objective is to get contrast on each of the curves (steepen the curbes) in the areas of interest. The same technique applies as in the tutorial to find the area of the curves to steepen, and they won't be the same in each channel. For a picture like this, you don't have to worry about messing up the color in the process.
Here are the curves I used
to produce this
An improvement, but not a major one. Somewhat better detail in the center of the flower and in the bee's body.
RE: "The Precise way to use levels to get great colors"
Craig...
Your video is good and it the process I'm aware of using the Threshold to Levels route to set white & black pt. Help me out here...
This process only works if you have a well defined black & white pt in the image? I first used it on my image above & enhanced the black on the bee. However, since there's no white pt...
John - Follow up questions. I’m going back over what you wrote & here is a few questions.
With the yellow flower (w/bee) image, there’s no “white point.” Under such circumstances, I still need to determine the brightest point using the Threshold command. In this case, the “white point” becomes getting the yellow as bright as I can. Got this part & here us were I get lost. My guess is that I need to understand the Color Wheel, or the color range variation in each channel, and/or the Info palette?
Blue Channel = 0 (O = Brightest yellow vs 255 = Blackest right?). You state this particular yellow looks a little on the orange side (I don’t have the experience yet to see this.) Therefore…
Red Channel = 247. How did you choose this value? This leaves what the Green channel out to be.
Green Channel = 231. Again, how did you know to come up with this value?
R, G, B = 5 for the black bee’s body. Why 5? I thought blackest value was 255?
It randomly generates a color, and you try to get the values for the color in RBG, Lab, or HSB. Of course, you need some understanding of the color space before you do it, but having a basic understanding, it hones your skills in identifying colors.
Blue Channel = 0 (O = Brightest yellow vs 255 = Blackest right?). You state this particular yellow looks a little on the orange side (I don’t have the experience yet to see this.) Therefore…
Red Channel = 247. How did you choose this value? This leaves what the Green channel out to be.
Green Channel = 231. Again, how did you know to come up with this value?
You're correct about the Blue channel. You want it to be 0, as this is the brightest yellow. For a pure yellow, you would have Red and Green at the maximum (255, although many prefer to reduce is slightly - I was following the tutorial recommendation to 247). From here, you can just reduce the Red or Green values slightly, to see what gives you the result that looks right to you. I decided looking at it that it was more orange (that is, more red), and so the Green value needed to be reduced. You could easily play with reducing one or the other to see which looks better. In any event, you're going to end up with a high value in both channels. When I did it, 231 in Green just looked right.
R, G, B = 5 for the black bee’s body. Why 5? I thought blackest value was 255?
No. The brightest value in any RGB channel is 255, the darkest is 0. Pure black is R=G=B=0. Again, some prefer to derate it slightly, and I was following the tutorial and used 5 instead of 0. (CMYK is a different beast altogether, but I won't go there).
But as you noticed earlier, a bright yellow is a very dark blue, and so the Blue channel will be close to 0 for that.
How to capture & post Curves window
Okay, I've finished working on a new image & want to upload it to get some feedback. With this next image, I've added more CS3 techniques, going from "as shot," to what I say, a custom finish. My idea of finish is by no means, complete!
I do have a few questions before posting my next image, which will not appear here, but the main "Finishing School" forum.
1) Posting image - I've created a category in my area just for PS, before & after images. From there, I'm okay with posting the forum image from this category, right? Anything I need to do/know before I proceed?
2) Sharpening - Suggestions? I spend time today reviewing a number of articles (Bill Frazier stuff was very informative. There were a few from here.) I know there's a difference between posting an image on the web vs for printing. From what I've read, "Lab Color" process appears to be the "best?" I can continue this discussion in whatever (non ACR) sharpening tutorial or thread there is.
3) When I post an image for post processing review is there some specific information I ought to note?
I've reworked the POP tutorial, take a look at it here.
And use this thread for any discussion or questions!
I am sure this question is going to get a laugh but how do you use this tutorial in Paint Shop Pro? I tried just doing the first steps but there is no way to "mark" anything in the threshold dialog box in PSP X or X!.
Regards,
gegjr
0
Marc MuenchRegistered UsersPosts: 1,420Major grins
edited April 29, 2008
Great tute David
Black and white points are simple yet complex
This is by far the single most important step in working an image in post
Something I did not read anywhare in this thread, the reason it is so important when printing. Yes, it does make the image fill the dynamic range thus POP, but what the numbers corrilate to are drops of ink on the paper. In the 0 to 255 scale, 0 representing black and 255 rep white, any area with 255 in all three RGB values, will hold no printing dot, in other words NO INK! just white paper or not so white paper or not even close to white paper. 0 on the other hand is a bit easier and in most cases, I agree with Vincent and setting the numbers to 7. However, with a accurate RIP there will be tonal differences between 0 and 5 so I always set my black point to 3, which is a compromise.
Also, I dont think every image needs a white point or in some cases even a full dynamic range This is why everything in photography, especially post, is IMAGE DEPENDENT. Therefore the black point is most important with the white point becoming cast-less less significant. I really wish ACR and LR would include RGB layers in the curves palette:cry
Even though this is a very old thread, the tutorial here is timeless. I followed the tutorial, using CS2 and I'm very impressed with the results. Here's the before and after. Thank you for this tutorial.
I read your contrast tute a while ago and was so ignorant that I didn't understand what I was reading. Now I have more experience and I get it and, more importantly, why it works.
Being the OCD type that I am, I like to know how to do stuff, but I REALLY like to know why something works.
OK, the questions:
In the last pane of page 1 and the first of page 2, you set the black value to #070707 and the white to #f7f7f7 (247, 247, 247). Why did you choose these values?
And, why is the black point not, for example, 248, 248, 248 (which would be 7 off of white - 255, 255, 255)?
Is there something magical about the number 7 (as in offsetting from full black by 7)?
Thanks again for the tute and TIA for the answers to the above questions.
On rereading this thread I see I missed this question Scott. Several people quoted Versace, Margulis and others, but did not really answer where they got their numbers. The best answer I have found is in "Fine Art Printing for Photographers" by Uwe Steinmuller and Juergen Gulbins published by Rocky Nook. I do like the books Rocky Nook publishes; they always seem to have the right blend of theory and downright practice. "Fine Art Printing for Photographers" really is quite worthwhile.
The white point and black point ultimately are derived from what you can print AND distinguish with YOUR printer and YOUR paper.
On page 79 there is a printer white point and black point test ramp - essentially a stepped grey scale from 0,0,0 to 255,255,255 that you must print with your printer and identify exactly where in the stepped scale you can begin to see a difference between the steps. If your printer cannot print steps that you can see with careful examination under good print lighting, below say 7,7,7 - then, there is no point in including that range in your image. If you cannot tell the difference between 247,247,247 and 255,255,255 then you have found your white point for your system. That is why Versace's numbers vary from Margulis. I believe Versace usually is printing with a fine art inkjet printer, and Margulis' usual printer concern is a CMYK linotype style industrial printer.
After performing this exercise with my Epson 3800, I favor 5,5,5 and 250,250,250 when I am printing on a satin lustre paper. For a matte paper, I might prefer a different set of numbers.
This is what Marc was saying just above, in a much more abbreviated fashion I believe. As he mentions, to a certain point it is image dependent, since some images may not need a full contrast range or a white point at all. A picture of fog, might suffer is expanded to a full range of tones.
I am looking forward to your book with great interest. I WILL purchase it as soon as it is available.
I did remember you mentioned that you were working with Rocky Nooke publishers. I do like the quality of the editing and printing they have in their books.
After I read the section on printing that I mentioned above, about where the white point and the black point numbers came from, image editing made more sense to me. But that is the only place I have ever seen it described so simply and clearly in print.
Comments
Good Luck,
Craig
which produced this
Then you can extend the contrast enhancement technique in the tutorial by curving the R, G, and B separately. The objective is to get contrast on each of the curves (steepen the curbes) in the areas of interest. The same technique applies as in the tutorial to find the area of the curves to steepen, and they won't be the same in each channel. For a picture like this, you don't have to worry about messing up the color in the process.
Here are the curves I used
to produce this
An improvement, but not a major one. Somewhat better detail in the center of the flower and in the bee's body.
Craig...
Your video is good and it the process I'm aware of using the Threshold to Levels route to set white & black pt. Help me out here...
This process only works if you have a well defined black & white pt in the image? I first used it on my image above & enhanced the black on the bee. However, since there's no white pt...
I’m going back over what you wrote & here is a few questions.
With the yellow flower (w/bee) image, there’s no “white point.” Under such circumstances, I still need to determine the brightest point using the Threshold command. In this case, the “white point” becomes getting the yellow as bright as I can. Got this part & here us were I get lost. My guess is that I need to understand the Color Wheel, or the color range variation in each channel, and/or the Info palette?
Blue Channel = 0 (O = Brightest yellow vs 255 = Blackest right?). You state this particular yellow looks a little on the orange side (I don’t have the experience yet to see this.) Therefore…
Red Channel = 247. How did you choose this value? This leaves what the Green channel out to be.
Green Channel = 231. Again, how did you know to come up with this value?
R, G, B = 5 for the black bee’s body. Why 5? I thought blackest value was 255?
~ Thanks ~
Yes. Here's one way to do it:
http://www.broadhurst-family.co.uk/lefteye/MainPages/a_challenge.htm
It randomly generates a color, and you try to get the values for the color in RBG, Lab, or HSB. Of course, you need some understanding of the color space before you do it, but having a basic understanding, it hones your skills in identifying colors.
You're correct about the Blue channel. You want it to be 0, as this is the brightest yellow. For a pure yellow, you would have Red and Green at the maximum (255, although many prefer to reduce is slightly - I was following the tutorial recommendation to 247). From here, you can just reduce the Red or Green values slightly, to see what gives you the result that looks right to you. I decided looking at it that it was more orange (that is, more red), and so the Green value needed to be reduced. You could easily play with reducing one or the other to see which looks better. In any event, you're going to end up with a high value in both channels. When I did it, 231 in Green just looked right.
No. The brightest value in any RGB channel is 255, the darkest is 0. Pure black is R=G=B=0. Again, some prefer to derate it slightly, and I was following the tutorial and used 5 instead of 0. (CMYK is a different beast altogether, but I won't go there).
But as you noticed earlier, a bright yellow is a very dark blue, and so the Blue channel will be close to 0 for that.
Right! I was turned around thinking about the histogram associated brightest with being more saturated.
Posting these questions is very helpful!
~ Thanks ~
Okay, I've finished working on a new image & want to upload it to get some feedback. With this next image, I've added more CS3 techniques, going from "as shot," to what I say, a custom finish. My idea of finish is by no means, complete!
I do have a few questions before posting my next image, which will not appear here, but the main "Finishing School" forum.
1) Posting image - I've created a category in my area just for PS, before & after images. From there, I'm okay with posting the forum image from this category, right? Anything I need to do/know before I proceed?
2) Sharpening - Suggestions? I spend time today reviewing a number of articles (Bill Frazier stuff was very informative. There were a few from here.) I know there's a difference between posting an image on the web vs for printing. From what I've read, "Lab Color" process appears to be the "best?" I can continue this discussion in whatever (non ACR) sharpening tutorial or thread there is.
3) When I post an image for post processing review is there some specific information I ought to note?
You've been a BIG help!
~ Much Thanks ~
I am sure this question is going to get a laugh but how do you use this tutorial in Paint Shop Pro? I tried just doing the first steps but there is no way to "mark" anything in the threshold dialog box in PSP X or X!.
Regards,
gegjr
Black and white points are simple yet complex
This is by far the single most important step in working an image in post
Something I did not read anywhare in this thread, the reason it is so important when printing. Yes, it does make the image fill the dynamic range thus POP, but what the numbers corrilate to are drops of ink on the paper. In the 0 to 255 scale, 0 representing black and 255 rep white, any area with 255 in all three RGB values, will hold no printing dot, in other words NO INK! just white paper or not so white paper or not even close to white paper. 0 on the other hand is a bit easier and in most cases, I agree with Vincent and setting the numbers to 7. However, with a accurate RIP there will be tonal differences between 0 and 5
Also, I dont think every image needs a white point or in some cases even a full dynamic range
Muench Workshops
MW on Facebook
Before:
After:
On rereading this thread I see I missed this question Scott. Several people quoted Versace, Margulis and others, but did not really answer where they got their numbers. The best answer I have found is in "Fine Art Printing for Photographers" by Uwe Steinmuller and Juergen Gulbins published by Rocky Nook. I do like the books Rocky Nook publishes; they always seem to have the right blend of theory and downright practice. "Fine Art Printing for Photographers" really is quite worthwhile.
The white point and black point ultimately are derived from what you can print AND distinguish with YOUR printer and YOUR paper.
On page 79 there is a printer white point and black point test ramp - essentially a stepped grey scale from 0,0,0 to 255,255,255 that you must print with your printer and identify exactly where in the stepped scale you can begin to see a difference between the steps. If your printer cannot print steps that you can see with careful examination under good print lighting, below say 7,7,7 - then, there is no point in including that range in your image. If you cannot tell the difference between 247,247,247 and 255,255,255 then you have found your white point for your system. That is why Versace's numbers vary from Margulis. I believe Versace usually is printing with a fine art inkjet printer, and Margulis' usual printer concern is a CMYK linotype style industrial printer.
After performing this exercise with my Epson 3800, I favor 5,5,5 and 250,250,250 when I am printing on a satin lustre paper. For a matte paper, I might prefer a different set of numbers.
This is what Marc was saying just above, in a much more abbreviated fashion I believe. As he mentions, to a certain point it is image dependent, since some images may not need a full contrast range or a white point at all. A picture of fog, might suffer is expanded to a full range of tones.
Moderator of the Technique Forum and Finishing School on Dgrin
Hey Jim
This is good to hear, as I am working on my book NOW for them:D
Your explanation regarding numbers is exactly what I was referring to.
Muench Workshops
MW on Facebook
I am looking forward to your book with great interest. I WILL purchase it as soon as it is available.
I did remember you mentioned that you were working with Rocky Nooke publishers. I do like the quality of the editing and printing they have in their books.
After I read the section on printing that I mentioned above, about where the white point and the black point numbers came from, image editing made more sense to me. But that is the only place I have ever seen it described so simply and clearly in print.
Moderator of the Technique Forum and Finishing School on Dgrin