Re: Color Cast Question
On Jul 9, 2006, at 7:16 AM, Shel Belinkoff wrote: As noted elsewhere, the cast may have resulted from two or more light sources (daylight, tungsten, fluorescent). Also, I sometimes work on photos very late at night, when my eyes are tired, and I may miss some subtleties. A color cast can come from a lot of sources actually, I don't know how it got there can only guess and repeat what others have said. I find it very very difficult to judge colour while editing, because the eye/brain adjusts to colour offsets quite easily. This is why I keep a light box next to my computer, so I can keep an eye on the original slide as a colour reference. For negs, I have a daylight-balanced tungsten bulb which I'll pop into my desk lamp: the minilab print will be useful as a starting point. Practice is improving my colour-correction skills, so by the time I start scanning my negs I might not hate them so much. - Dave -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
As noted elsewhere, the cast may have resulted from two or more light sources (daylight, tungsten, fluorescent). Also, I sometimes work on photos very late at night, when my eyes are tired, and I may miss some subtleties. A color cast can come from a lot of sources actually, I don't know how it got there can only guess and repeat what others have said. Shel [Original Message] From: Kostas Kavoussanakis whatsoever to those who noted a blue, green or even yellow cast. More interesting were the number of ways to eliminate the cast that others said didn't exist. I'm sure there will be more comments waiting for me when I check my mail further ;-)) Will you also tell us how the cast got there? Is it a reflection, or post-processing or... -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On Jul 7, 2006, at 7:32 AM, Bob W wrote: It's a very interesting process - you don't even need a calibrated monitor, or a colour monitor even. Just by picking the brightest white where you want to hold detail, and the darkest black ditto, then setting them to some combination of CMYK (in the article, but later he shows it with RGB apparently - I don't have the book yet) you should be able to make everything else fall into its rightful place, colourifically. This is basically the technique I use when processing my scans. I use the numbers to set both the white black points to be as neutral as possible, at a certain brightness level. Most of the time that's all the colour correction I need to do, but sometimes I need to make a few more adjustments. This shouldn't be followed religiously: last night I was working on some more sunsets and found that the shadows really did need to be slightly redder than neutral. Sometimes I'll encounter a pic that doesn't have black and/or white points. These ones are usually quite easy for me as minor casts don't seem to be as noticeable if there's nothing neutral, so I'll just look at the slide on the light box (one reason why I hate scanning negs!) and adjust from there. If it all turns to custard, just convert to BW :) I could waffle on a bit more, but it's nearly dinnertime... - Dave -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
On Thu, 6 Jul 2006, Shel Belinkoff wrote: whatsoever to those who noted a blue, green or even yellow cast. More interesting were the number of ways to eliminate the cast that others said didn't exist. I'm sure there will be more comments waiting for me when I check my mail further ;-)) Will you also tell us how the cast got there? Is it a reflection, or post-processing or... Thanks, Kostas -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
I think your getting a variety of responses because the color cast of the shot is fairly close to what one might call neutral. As Godfrey demonstrated scientifically, there's a bit of blue in the whites, but the overall look is certainly within the range of acceptable color. So the aesthetic judgement, using the eye alone, becomes a matter of personal preference. I would call the color cast cool, but nice. I might warm it a touch if it was mine, but again that's personal preference. You're obviously going to get a wide range of answers, because some prefer a slightly warmer look, while others prefer a cooler look. Paul On Jul 6, 2006, at 11:51 PM, Shel Belinkoff wrote: Hi Tom, Bob ... There are many ways to achieve a specific result in Photoshop, rarely a best way - that's one of the things that makes it, to me at least, such a neat program. BTW, I asked about the color cast not only here, but on the Photoshop mailing list and on theAdobe Photoshop User-to-User forum, where a lot of PS experts hang out. I was somewhat surprised at the wide range of responses, from several people saying the image had no color cast whatsoever to those who noted a blue, green or even yellow cast. More interesting were the number of ways to eliminate the cast that others said didn't exist. I'm sure there will be more comments waiting for me when I check my mail further ;-)) Shel [Original Message] From: Tom C My point is that traditionally a filtering mechanism is used either at image capture time or at print time to provide color correction for the rendered image. By suggesting a warming filter in Photoshop be used, I was merely suggesting that an analog of the traditional approach be used. I don't know the best way to something all the time, but I may know a way that works. :-) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
Hi! Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html The highlights are slightly bluish-cyanish on my screen. Although it is not really a cast of all the picture, just some elements of it. Boris -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On 6/7/06, Shel Belinkoff, discombobulated, unleashed: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Yes, just a tad. PowerBook G3, Mac OS 10.4.5, Safari 2.0.3 But you won't see this message. So pretend I didn't write it. Pretend I deleted it before I sent it. Life is good :-) -- Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=|http://www.cottysnaps.com _ -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On Thu, 6 Jul 2006, Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html I don't have a calibrated monitor but I think so. I have had this symptom with cheap flashes, but it could be other things too. Kostas -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
More greenish I think. Don Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Shel -- Dr E D F Williams www.kolumbus.fi/mimosa/ http://personal.inet.fi/cool/don.williams/ 41660 TOIVAKKA – Finland - +358400706616 -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
Yep... too cool, IMO. Might try one of Photoshop's warming filters as a quick fix. Tom C. From: Shel Belinkoff [EMAIL PROTECTED] Reply-To: Pentax-Discuss Mail List pdml@pdml.net To: PDML PDML@pdml.net Subject: Color Cast Question Date: Thu, 6 Jul 2006 09:02:32 -0700 Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Shel -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
I've just reset my screen with Adobe and I think the picture looks fine. No perceivable cast. Don W Kostas Kavoussanakis wrote: On Thu, 6 Jul 2006, Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html I don't have a calibrated monitor but I think so. I have had this symptom with cheap flashes, but it could be other things too. Kostas -- Dr E D F Williams www.kolumbus.fi/mimosa/ http://personal.inet.fi/cool/don.williams/ 41660 TOIVAKKA – Finland - +358400706616 -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On Jul 6, 2006, at 9:02 AM, Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Yes. It has a slight bluish cast to my eye on my calibrated monitor, and Photoshop's analysis tools allow me to see the blue in the highlights (make a small selection and move it around the screen like a sampler, read using the Histogram palette). Put a 5x5 sampler on the white fur by the cat's nose and another in the specular reflection on the bowl. Add a Curves adjustment layer and use the white point selector to sample and set a curve on each of those points. You'll see that the auto adjustment selected pushes the green and red channels to a steeper angle to compensate for the blue. Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
Looks OK to me - on a monitor calibrated with a Spyder about 3 days ago -P Don Williams wrote: I've just reset my screen with Adobe and I think the picture looks fine. No perceivable cast. Don W Kostas Kavoussanakis wrote: On Thu, 6 Jul 2006, Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html I don't have a calibrated monitor but I think so. I have had this symptom with cheap flashes, but it could be other things too. Kostas -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
Maybe a little, but it's pretty clean on my monitor. Less cast than you'd find in an old Ektachrome slide Shel Belinkoff wrote: Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Shel -- When you're worried or in doubt, Run in circles, (scream and shout). -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
This is an interesting thread for me, and an interesting reply from Tom. I have been mulling whether to ask something about colour correction, but I can't readily formulate a question at the moment. As you know, I am going to buy a new printer soon, and intend to use a fully colour-managed workflow. Now, like many men I am red/green colourblind - to the extent that I get all the flash cards wrong in colour-blindness tests, so I don't trust the evidence of my own eyes when colour is involved. Therefore for a colour-managed workflow I will need to work by numbers. I have dug out and re-read Color correction by numbers by Dan Margulis. http://www.ledet.com/margulis/PP7_Ch02_ByTheNumbers.pdf It's a very interesting process - you don't even need a calibrated monitor, or a colour monitor even. Just by picking the brightest white where you want to hold detail, and the darkest black ditto, then setting them to some combination of CMYK (in the article, but later he shows it with RGB apparently - I don't have the book yet) you should be able to make everything else fall into its rightful place, colourifically. This relies on some assumptions, of course, but you should be able to select an area that ought to be white, or black, look at the relationships between the numbers as against the 'correct' numbers for the white you want, and determine from that what type of cast there is over the whole picture. No doubt there are drawbacks to this technique, but it seems like a reasonably good way of getting an objective answer to your question, and a more balanced approach than applying a quick fix filter. -- Cheers, Bob -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom C Sent: 06 July 2006 17:32 To: pdml@pdml.net Subject: RE: Color Cast Question Yep... too cool, IMO. Might try one of Photoshop's warming filters as a quick fix. From: Shel Belinkoff [EMAIL PROTECTED] Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Shel -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On Jul 6, 2006, at 12:32 PM, Bob W wrote: ... No doubt there are drawbacks to this technique, but it seems like a reasonably good way of getting an objective answer to your question, and a more balanced approach than applying a quick fix filter. ... Yes, setting color values by number actually does work well, presuming you understand the scene characteristics. The drawback to this kind of technique moves beyond the science of accuracy and measurement, where it works very well, to the realm of aesthetic values ... the goal in making color adjustments is to obtain a pleasing rendering, which are often not accurate in a technical sense. For instance, most photographers find a small percentage extra yellow or red in a portrait makes a much more pleasing photo than accurately portraying the cool tones of a blue sky's reflection in highlights and skin tones. Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
Hi Bob, I find that it's often the results that count, not the process. Somebody very technically adept with Photoshop for instance may do a 3-step process to make a correction and might indeed have a good reason for doing so. If I use a quicker route to achieve the desired effect or correction, not knowing there might be a technically better way... well who knows when looking at the end photo how a particlar rendering was arrived at? With no reference for comparison, one generally accepts that the image displayed is as desired. By way of example, Shel suggested his image had a bluish cast. I saw it, but I might not have recognized it at all, except for power of suggestion. Others did not see a color cast at all. IMO, the filter is there for a reason, it produces a desired effect with possibly a great saving of time. In my mind, it's identical to putting a filter over the lens instead of changing the lighting itself. I agree that the more knowledge of the process and therefore control one has the better. I don't know what the filter is doing behind the scenes, maybe a process similar to what would be done manually without using the filter. If one simply wants the entire photograph to be rendered slightly differently, there's often a quick route that's not necessarialy destructive and produces the desired result. How would a color negative exhibiting a bluish cast be corrected when printing??? Rhetorical question. Tom C. From: Bob W [EMAIL PROTECTED] Reply-To: Pentax-Discuss Mail List pdml@pdml.net To: 'Pentax-Discuss Mail List' pdml@pdml.net Subject: RE: Color Cast Question Date: Thu, 6 Jul 2006 20:32:39 +0100 This is an interesting thread for me, and an interesting reply from Tom. I have been mulling whether to ask something about colour correction, but I can't readily formulate a question at the moment. As you know, I am going to buy a new printer soon, and intend to use a fully colour-managed workflow. Now, like many men I am red/green colourblind - to the extent that I get all the flash cards wrong in colour-blindness tests, so I don't trust the evidence of my own eyes when colour is involved. Therefore for a colour-managed workflow I will need to work by numbers. I have dug out and re-read Color correction by numbers by Dan Margulis. http://www.ledet.com/margulis/PP7_Ch02_ByTheNumbers.pdf It's a very interesting process - you don't even need a calibrated monitor, or a colour monitor even. Just by picking the brightest white where you want to hold detail, and the darkest black ditto, then setting them to some combination of CMYK (in the article, but later he shows it with RGB apparently - I don't have the book yet) you should be able to make everything else fall into its rightful place, colourifically. This relies on some assumptions, of course, but you should be able to select an area that ought to be white, or black, look at the relationships between the numbers as against the 'correct' numbers for the white you want, and determine from that what type of cast there is over the whole picture. No doubt there are drawbacks to this technique, but it seems like a reasonably good way of getting an objective answer to your question, and a more balanced approach than applying a quick fix filter. -- Cheers, Bob -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom C Sent: 06 July 2006 17:32 To: pdml@pdml.net Subject: RE: Color Cast Question Yep... too cool, IMO. Might try one of Photoshop's warming filters as a quick fix. From: Shel Belinkoff [EMAIL PROTECTED] Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Shel -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
How would a color negative exhibiting a bluish cast be corrected when printing??? Rhetorical question. Tom C. Rhetorical answer: Do you mean a digital print or a traditional print? I know absolutely nothing about traditional colour printing, and probably never will. For digital printing from a colour neg I don't know for sure, but I suppose from reading the article (I stress that I haven't actually tried any of this yet) that you look for something that is neutral in the real world, preferably black or white, and set that to the colour values that closely match the real world colour values. Everything else should fall into place since all the relationships in between the black and white values are maintained. Bob -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
We are probably having a tangential conversation. :-) I was referring to a traditional print. The enlarger has filters for the light source that affect the color balance of the light that reaches the negative. My point is that traditionally a filtering mechanism is used either at image capture time or at print time to provide color correction for the rendered image. By suggesting a warming filter in Photoshop be used, I was merely suggesting that an analog of the traditional approach be used. I don't know the best way to something all the time, but I may know a way that works. :-) Tom C. From: Bob W [EMAIL PROTECTED] Reply-To: Pentax-Discuss Mail List pdml@pdml.net To: 'Pentax-Discuss Mail List' pdml@pdml.net Subject: RE: Color Cast Question Date: Thu, 6 Jul 2006 21:36:32 +0100 How would a color negative exhibiting a bluish cast be corrected when printing??? Rhetorical question. Tom C. Rhetorical answer: Do you mean a digital print or a traditional print? I know absolutely nothing about traditional colour printing, and probably never will. For digital printing from a colour neg I don't know for sure, but I suppose from reading the article (I stress that I haven't actually tried any of this yet) that you look for something that is neutral in the real world, preferably black or white, and set that to the colour values that closely match the real world colour values. Everything else should fall into place since all the relationships in between the black and white values are maintained. Bob -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
How would a color negative exhibiting a bluish cast be corrected when printing??? Rhetorical question. Whether it's rhetorical or not, WillieR can answer this more precisely than I, but I expect you would add a little magenta and subtract some cyan in the filter pack. Negative printing to paper in traditional process is a subtractive color setup, or CMY based. Usually you leave one color fixed when you're close. In the digital domain, you usually work in additive color space, RGB, so you would add R+G to reduce the B or subtract some B. Same difference. ;-) Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
... No doubt there are drawbacks to this technique, but it seems like a reasonably good way of getting an objective answer to your question, and a more balanced approach than applying a quick fix filter. ... Yes, setting color values by number actually does work well, presuming you understand the scene characteristics. The drawback to this kind of technique moves beyond the science of accuracy and measurement, where it works very well, to the realm of aesthetic values ... the goal in making color adjustments is to obtain a pleasing rendering, which are often not accurate in a technical sense. Yes, I'm sure you're right. The problem for colourblind people, though, is that something that looks ok to us can look absurd to other people. Why is the sky yellow, Bob?. When the intention is to show something as realistically as possible then colourblind people have few options. Incidentally, I don't necessarily agree that the goal is to obtain a pleasing rendering, but then one can easily get into a long discussion about realism versus aesthetics. That's for some other time and some other thread. For instance, most photographers find a small percentage extra yellow or red in a portrait makes a much more pleasing photo than accurately portraying the cool tones of a blue sky's reflection in highlights and skin tones. The photographer Terence Donovan (or perhaps it was David Bailey) has been quoted as justifying their overuse of warm filters by saying whoever heard of a f-cking client complaining because their picture was too warm?, so clearly you have something there. But the technique Margulis describes appears to work for all kinds of skin tones too. Regards, Bob -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On Jul 6, 2006, at 3:23 PM, Bob W wrote: ... The problem for colourblind people, though, is that something that looks ok to us can look absurd to other people. Why is the sky yellow, Bob?. When the intention is to show something as realistically as possible then colourblind people have few options. Not to disparage colorblind folks, but they should always have a person with full color vision proof their color photos. Taking the path to accuracy in rendering will at least ensure a good baseline. Setting the color by the numbers will work well for that. Incidentally, I don't necessarily agree that the goal is to obtain a pleasing rendering, but then one can easily get into a long discussion about realism versus aesthetics. That's for some other time and some other thread. Yes, this is a long discussion akin to the What Are You Trying To Say? thread which I have as yet not appended my thoughts to. I've been too busy trying to say something in the past couple of weeks to write about it. ;-) Needless to say, photographs *can* encompass more than just realistic rendering. What they ought to present is up to the intent of the photographer... The photographer Terence Donovan (or perhaps it was David Bailey) has been quoted as justifying their overuse of warm filters by saying whoever heard of a f-cking client complaining because their picture was too warm?, so clearly you have something there. But the technique Margulis describes appears to work for all kinds of skin tones too. :-) Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
On 7/7/06, Tom C [EMAIL PROTECTED] wrote: How would a color negative exhibiting a bluish cast be corrected when printing??? Rhetorical question. I was taught to subtract the cast or add the complementary colour. Cheers, Dave -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
Re: Color Cast Question
- Original Message - From: Shel Belinkoff Subject: Color Cast Question Does this pic have a bluish cast to it? http://home.earthlink.net/~morepix/sunrabrunch.html Yup. William Robb -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
RE: Color Cast Question
Hi Tom, Bob ... There are many ways to achieve a specific result in Photoshop, rarely a best way - that's one of the things that makes it, to me at least, such a neat program. BTW, I asked about the color cast not only here, but on the Photoshop mailing list and on theAdobe Photoshop User-to-User forum, where a lot of PS experts hang out. I was somewhat surprised at the wide range of responses, from several people saying the image had no color cast whatsoever to those who noted a blue, green or even yellow cast. More interesting were the number of ways to eliminate the cast that others said didn't exist. I'm sure there will be more comments waiting for me when I check my mail further ;-)) Shel [Original Message] From: Tom C My point is that traditionally a filtering mechanism is used either at image capture time or at print time to provide color correction for the rendered image. By suggesting a warming filter in Photoshop be used, I was merely suggesting that an analog of the traditional approach be used. I don't know the best way to something all the time, but I may know a way that works. :-) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
