Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: Hening Bettermann on December 27, 2012, 01:57:15 pm
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I had a bright moment and have figured out how to set the natural (visually correct) white balance at shooting time. But before I reveal the secret, you have to guess: which one of these 4 shots of this gorgeous scene has the most natural white balance?
#1 (7296) is the AWB
:-) Hening
Well uploading the images does not work. Not even a single one of 550 kB.
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new attempt uploading images
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The right number is the one that produces the appearance you desire. Any Kelvin values you find are a range of color. The same values in one converter can look quite different in another. The values are correlated from something that isn't real but theoretical (the black body radiator). YMMV.
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Hi Andrew
thank you for chiming in.
The appearance I desire is the appearance I saw at shooting time, and I exspect my processing pipeline to reproduce that.
The 4 images above were developed in Raw Developer, my camera profile, linear settings.
These below are processed in ACR, Adobe Standard camera profile, linear settings.
It seems to me that the relative difference between white balances persists quite well through the change of raw processor even with different camera profiles.
Good light - and true color.
Hening.
Oh, I forgot to mention that the Kelvin values were those set at shooting time, not in the raw processor.
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The bottom one has the most natural WB. What's the secret?
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You are right!
Here's the secret/recipe:
Set WB to manual. Take a shot based on an estimate. Step a little bit back from the tripod, so that you view the camera screen image and the scene at the same time. Adjust WB based on comparing the two. Take new shot and repeat until you are satisfied.
It is so ridiculously simple - yet I have not seen it described anywhere, and nobody mentioned it when I asked about how to set the WB manually, on this forum
http://www.luminous-landscape.com/forum/index.php?topic=30688.0;wap2
WB bracketing may be be helpful. My Canon 5D2 does not display the bracketed values by the numbers, but 3 units seem to equal 500 K.
If the camera had a physical dial to adjust the WB (as well as live view), shots would not be needed.
Good light - and true color!
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Hi Andrew
thank you for chiming in.
The appearance I desire is the appearance I saw at shooting time, and I exspect my processing pipeline to reproduce that.
The 4 images above were developed in Raw Developer, my camera profile, linear settings.
These below are processed in ACR, Adobe Standard camera profile, linear settings.
It seems to me that the relative difference between white balances persists quite well through the change of raw processor even with different camera profiles.
Good light - and true color.
Hening.
Oh, I forgot to mention that the Kelvin values were those set at shooting time, not in the raw processor.
Personally I don't see the point of this. Andrew's response is to me a valid point. However if you think the idea has merit then in ACR Adobe Neutral would be a better choice than Adobe Standard if you wish to make everything neutral. As to viewing the image on the back of the camera then what you are trying to match is a jpeg rendering of your RAW information, so a comparison won't be accurate. Setting Kelvin values in camera is at best a wild guess as to the scene in front of you and there isn't anything at all accurate about the whole exercise hence the reason nobody has admitted trying it before? :)
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Here's the secret/recipe:
Set WB to manual. Take a shot based on an estimate. Step a little bit back from the tripod, so that you view the camera screen image and the scene at the same time. Adjust WB based on comparing the two. Take new shot and repeat until you are satisfied.
You must be joking! :o
There's a reason why you never read that anywhere.
Camera display...
1) is often less than sRGB
2) is viewed in suboptimal conditions
3) refers to the style that has been cooke by that specific brand
It's no way a good nor precise way to set the WB.
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WB bracketing may be be helpful. My Canon 5D2 does not display the bracketed values by the numbers, but 3 units seem to equal 500 K.
If the camera had a physical dial to adjust the WB (as well as live view), shots would not be needed.
Assuming you're shooting raw, not so. The WB setting has zero effect on raw data. It is simply a metadata suggestion and again, based on a system of values that simply do not define an exact color! There's no reason to bracket the metadata, it would do nothing to the raw data. There's a reason, at least in Adobe raw converters (and others) we have control over Tint/Temp (WB over Magenta/Green and Yellow Blue color axis). No one value will be correct until you, the image creator decides what looks best and NOT using that pretty awful LCD on the camera which only shows you the effect of WB based on a JPEG. Unless you are capturing a JPEG and you use the manufacture’s converter (which may or may not deal with the metadata 'better' than another converter), you're wasting your time on site futzing with WB settings.
Here's where you need to go to understand why a CCT Kelvin value is a range of colors and that depending on a large number of factors, the same set of values will look pretty different depending on what is deciphering those numbers.
http://www.ppmag.com/reviews/200512_rodneycm.pdf
After that, you may wish to read this piece which explains why you are not getting "accurate" color but maybe preferred color:
http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf
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Assuming you're shooting raw, not so. The WB setting has zero effect on raw data. It is simply a metadata suggestion and again, based on a system of values that simply do not define an exact color! There's no reason to bracket the metadata, it would do nothing to the raw data. There's a reason, at least in Adobe raw converters (and others) we have control over Tint/Temp (WB over Magenta/Green and Yellow Blue color axis). No one value will be correct until you, the image creator decides what looks best and NOT using that pretty awful LCD on the camera which only shows you the effect of WB based on a JPEG. Unless you are capturing a JPEG and you use the manufacture’s converter (which may or may not deal with the metadata 'better' than another converter), you're wasting your time on site futzing with WB settings.
The white balance setting has no effect on the raw file, but a white balance value is needed to properly render the appearance of the scene. As an example, here is a screen shot of an image shot with UniWB set on the camera. You can adjust the WB to obtain an image that is pleasing to you, but if you want to recover the actual appearance of the flower you need to know a WB setting that will enable an accurate reproduction of the flower.
The takehome point, is that if the scene contains no recognizable neutral values, you should shoot with a WhiBal or similar card in the scene or take a shot of the WhiBal under the same illumination.
Interested users may download the file here (https://docs.google.com/uc?id=0B03pK8ybOtKla0ZvbzNodDdDd1E&export=download). (warning 38 MB)
Regards,
Bill
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Hi again
I have now read your (Andrew's) article on white point and re-read the ICC white paper.
I am aware of that scene-referred data have to be translated (rendered) to human vision, which is non-linear, unlike the camera sensor. This process of translation will necessarily imply individual judgement, in particular w.r.t. the tone curve. This is in my eyes NOT a carte blanche to whatever arbitrariness. We should try to apply a terminology that at least theoretically enables us to describe the difference between a naturalistic, if by necessity subjective, rendering intent and e.g. an intended change of hues. Using the term "pleasing" for both is confusing.
jpeg
I am painfully aware of, that the in-camera jpeg is only very loosely linked to the raw data - because the camera maker does exactly what you advice me to do: just make it look pretty. I am not exspecting or claiming that my "method" gives color accuracy to the 3rd post comma digit. Nevertheless, with a precision level as coarse as 1,000°K, it could produce an image, that was MUCH closer to the scene than the AWB. Just picking the prettiest might have led me to #3.
The bracketing is only intended for the visual comparison, not believing that it will change the raw data. I will trash the shots after I have decided on the WB.
The magenta-green axis
I am aware of that that this is to be considered. But how much does the daylight change during the day along this axis? In another thread on this forum, which I fail to retrieve right now, I was told that it changes very little, and have since set the Tint in the raw converter to zero.
The difference between different (well, 2 so far) raw converters seems to be far less than the differences between the AWB and my "method".
Let's turn it around: Which are my alternatives?
AWB - see above.
Gray card, WhiBal and the like: Will theoretically make every image look like it was shot at noon.
Using a fixed value of say 5,500 K (which is what I have done lately): Well, #2 of my images is 6,000 K, and it's way off.
Maybe I can put it this way: the in-camera jpeg, despite all its shortcomings, still seems to be a tool that is my best bet in this situation. Better than AWB, and better than my memory after the shooting.
Good light - and true color
Bill, this was written before I read your post. I may return later.
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Bill,
I think the gray card method will give accurate color for the flower seen as an isolated object. But I think it will not solve the problem that "panopeeper" describes in the thread linked to in my above post #5: (page 1 in that thread as linked)
"When in the Lower Antelope Canyon, in Arizona, I shot a white card for later WB. When back home, developing the raw images, I tried to WB them based on that shot. The result was horrendeous. Although the resulting color matched the sand (we took a tiny amount in a small plastic bag), it did not resemble at all the scenery as I saw it, because the entire canyon inside was not lit by the "original" sunshine but by the reflections on the walls. Ultimately, I WBd based on my memory.
When shooting in a night club or bowling alley or other place, where the illumination is intentionally unnatural, like black light, should one WB so, that a white shirt become white? That would ruin the mood. I admit I have no idea how such a shot should be WBd if not purely subjectively."
I think that my "method" is a step in the direction to answer that last question. It views and compares the scene as a whole with all the reflections in place.
edit:
I think the gray card method will not show the color of the flower as you saw it at shooting time, because it will change that light into the light that makes the gray card neutral. (of course, if the light was near average daylight, the difference will be small).
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The magenta-green axis
I am aware of that that this is to be considered. But how much does the daylight change during the day along this axis?
Doesn't matter. It's just another rendering control to produce a desired image appearance. How much does daylight change that affects Clarity?
Let's turn it around: Which are my alternatives?
AWB - see above.
Gray card, WhiBal and the like: Will theoretically make every image look like it was shot at noon.
Using a fixed value of say 5,500 K (which is what I have done lately): Well, #2 of my images is 6,000 K, and it's way off.
Lots and lots of scenes do not warrant any WB (a model on the beach at sunset). WB that with a card, you get an awful appearing image. Again, whatever the value, it is simply a suggestion by any number of sources and in no way have to be honored even if honoring them would produce similar results in different products (it will not for all the reason's discussed).
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The magenta-green axis
I am aware of that that this is to be considered. But how much does the daylight change during the day along this axis? In another thread on this forum, which I fail to retrieve right now, I was told that it changes very little, and have since set the Tint in the raw converter to zero.
Bill, this was written before I read your post. I may return later.
While the magenta/green axis doesn't change a lot in normal blackbody radiators, the response of the magenta/green by a sensor can. Setting your Tint to zero is a mistake because ACR/LR looks at both the K & Tint to normalize White Balance. To have zero Tint is likely to be wrong in 90% + cases...
Really, your best bet for "accurate" vs. "pleasing" white balance is to shoot a known target and use the WB tool to set the starting point. Yes, there are problems if the light falling on the target is different in various areas of a scene...life's a bitch and then ya die, deal with it.
I'm reminded of a lecture Stephen Johnson gave on the Antarctic trip in 2009 (the 3rd of our trips to Antarctica). His whole lecture was about White Balance and he basically through up his hands and said it's impossible to have a technically accurate WB setting in Antarctic light. He shot a variety of "targets) and never got an "accurate" WB setting because, well, light it really, really tricky. His best advice (as I remember it) was to yank on the sliders until the image "looked" like you though it looked. If you know Stephen you would realize that what you though you saw and what you wanted to see and what you ended up capturing was all very different. At some point you need to get over what you though you saw and make the adjustments needed to make it look like what you want it to look like.
The bottom line? Sensors and human eyeballs are different...you can jump though as many hoops as you want, but what really matters is what you see on the display when you are done making your personal adjustments. There is zero chance of capturing what you thought you saw with your eyes...the best you can hope for is something that has a close approximation to what you think you saw. BTW, this all depends on the original illumination and it's luminance...any time you look at dimly lit scenes (such as the example image) your visual color accuracy goes right out the window.
The moment you think you have the keys to the universe, some SOB will change the locks...sorry bud, but you are barking up the wrong tree :~)
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Lots and lots of scenes do not warrant any WB (a model on the beach at sunset). WB that with a card, you get an awful appearing image. Again, whatever the value, it is simply a suggestion by any number of sources and in no way have to be honored even if honoring them would produce similar results in different products (it will not for all the reason's discussed).
That depends on what is meant by white balance. If you want the camera to reproduce the actual colors of the scene as accurately as possible, a white balance setting of 5500K is best, because the spectral power distribution for that color temperature is relatively flat, approaching an equal power distribution (Illuminant E (https://docs.google.com/uc?id=0B03pK8ybOtKla0ZvbzNodDdDd1E&export=download)). If no white balance at all is applied, the scene will appear quite green because most cameras are most sensitive to green. A white balance setting is needed to balance the output of the color channels.
Shown below is a sunset scene with daylight white balance of 5500K and without any white balance. Also shown are the SPDs of various natural illuminants. The spectrum of D55 is relatively flat over most of the visible spectrum.
Bill
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Hi again
I have now read your (Andrew's) article on white point and re-read the ICC white paper.
I am aware of that scene-referred data have to be translated (rendered) to human vision, which is non-linear, unlike the camera sensor. This process of translation will necessarily imply individual judgement, in particular w.r.t. the tone curve. This is in my eyes NOT a carte blanche to whatever arbitrariness. We should try to apply a terminology that at least theoretically enables us to describe the difference between a naturalistic, if by necessity subjective, rendering intent and e.g. an intended change of hues. Using the term "pleasing" for both is confusing.
Hening,
It is a misunderstanding that our images are gamma encoded since the human vision is nonlinear (near logarithmic) and the gamma encoding is necessary to accommadate human vision. When the image is shown on the screen, the gamma encoding is reversed so that the final system gamma is close to 1.0. This is explained clearly by Sean McHugh on the Cambridge in Color web site (http://www.cambridgeincolour.com/tutorials/gamma-correction.htm). If the reproduction is to be viewed with a dark surround as in a movie theater, the gamma 1 reproduction will appear flat and an overall gamma of 1.5 is preferable as explained here (http://www.w3.org/TR/PNG-GammaAppendix.html).
Scene referred images do appear flat when tone mapping is done to fit the luminances to a low dynamic range output device. However, if one has a high dynamic range output device, a scene referred image will reproduce the actual scene. Modern displays do have a relatively large DR and a scene referred will look fine in most cases if one uses the proper profile such as LinearRimm. Otherwise, the scene referred image will appear dark.
Regards,
Bill
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Bill, how do you set your camera to 5500k? The numbers on my nikon d700 and d800 do not give identical results.
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His best advice (as I remember it) was to yank on the sliders until the image "looked" like you though it looked. If you know Stephen you would realize that what you though you saw and what you wanted to see and what you ended up capturing was all very different. At some point you need to get over what you though you saw and make the adjustments needed to make it look like what you want it to look like.
BRAVO! At some point we need to stop thinking "Perfect" color, and create with our minds eye. Be the Artist and interpret what we Feel and not what just what we see.
Peter
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Bill, how do you set your camera to 5500k? The numbers on my nikon d700 and d800 do not give identical results.
Since 5500K is not a standard preset, you have to go to the shooting menu and navigate to the white balance tab and select choose color temperature and then set the color temperature as shown. As to the identical results on the D700 and D800, i'm not sure what you mean. If you are in Lightroom/ACR, ignore the color temperature and tint. For my D800e with 5500K and no tint, the ACR reading is 5300K and tint of +6.
Regards,
Bill
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If you want the camera to reproduce the actual colors of the scene as accurately as possible...
In the context of this tread, the use of the term "accurate color" isn't useful and isn't even an accurate term <g>. It only serves to confuse the OP and others. The OP is asking about setting a CCT value on the camera, which has no bearing on the raw data and will be interpreted by differing processes to an extent that the term "accurate" needs to be left out of the conversation. The OP should listen to the words of Steve Johnson who knows a few things about digital capture and image processing! The latest and most salient point the OP should be looking over, instead of digging a deeper rabbit hole in terms of "accurate" color and setting CCT values is this:
At some point we need to stop thinking "Perfect" color, and create with our minds eye. Be the Artist and interpret what we Feel and not what just what we see.
Peter
Maybe if someone on LuLa sets up a forum for scientific capture of digital images, the discussion would be better there. In this context, creating imagery with color in context, it's just a digression into theoretical verbal masturbation. Make the image appear on your calibrated display (or not, just on the print itself) as you desire. There's no accurate matrix one can assign to that process and for good reasons.
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His best advice (as I remember it) was to yank on the sliders until the image "looked" like you though it looked. If you know Stephen you would realize that what you though you saw and what you wanted to see and what you ended up capturing was all very different. At some point you need to get over what you though you saw and make the adjustments needed to make it look like what you want it to look like.
BRAVO! At some point we need to stop thinking "Perfect" color, and create with our minds eye. Be the Artist and interpret what we Feel and not what just what we see.
Peter
For artistic photography, Jeff's advice is well taken. However, for documentary photography one aims to reproduce the scene or the perception of the scene. For the former, an accurate white balance is needed. For the latter, one must take human perception into account. The OP wanted to reproduce the scene as he perceived it. The scene was relatively dark, likely in the range of mesopic vision (http://en.wikipedia.org/wiki/Mesopic_vision). As Jeff pointed out, color perception is decreased as one is going into darkness. Also, if one wants to reproduce the appearance of the scene, chromatic and dark adaption must be taken into account. His empiric approach was relatively crude and limited by the camera's LCD, but it got the job done. The Photoshop CIECAM02 plugin (https://sites.google.com/site/clifframes/ciecam02plugin) can help in adjusting the appearance of the reproduction.
Regards,
Bill
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For artistic photography, Jeff's advice is well taken. However, for documentary photography one aims to reproduce the scene or the perception of the scene.
Perception, key word above. I suspect the same is true for non documentary photography and neither the subject nor the photographers intent changes the facts that there's nothing accurate here, certainly past someone saying they feel it's accurate. We could both be at the same scene, shooting it together with identical cameras and settings. You could say what you captured is "accurate" or looks as you recall it, I could say you're way off base. Neither of us can provide anything scientific to say our perception of either the scene or the capture is more accurate than the other. The concepts don't belong here. They might belong in a post about capturing data using some kind of sound, scientific method and using some sound analytically useful tools.
Even IF you could provide that your capture was colorimetrically accurate than mine, if I like my capture better, the story is over. Accurate loses over desired color appearance for the vast majority of the people making images who come to LuLa.
People can discuss how many ICC profiles can theoretically dance on the head of a pin, or what CCT value on a camera produces "accurate" colors, I don't see how this will in any way aids in creating preferable appearing images.
What's more accurate, Fujichrome, Ektrachrome or (ugh) Agafchrome? Answer, doesn't matter. What matters is which film stock do you visually prefer and thus buy and use.
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Hi Bill,
so it was you who posted that graph in that old WB thread of mine. The cached version I found through Google is stripped of images. Thank you for providing it, then and now.
The value of 6,000 K (close to 5,500) did not work well in my test as can be seen.
> Also, if one wants to reproduce the appearance of the scene, chromatic and dark adaption must be taken into account. His empiric approach was relatively crude and limited by the camera's LCD, but it got the job done.
Exactly. I am of course aware of the limitations of the camera screen and the in-camera jpeg, and the precision level of 1,000°K can be raised to 100°K (on the Canon 5D2). But even at 1,000°, my "method" could do something no other method I know of can. One may see it as a crunch to a freehand estimate of the Kelvins, including not only the light, but also its reflections through the scene, and phenomena specific for human vision. Just like the grayscale step wedge in the old days was in estimating the EV.
> Even IF you could provide that your capture was colorimetrically accurate than mine, if I like my capture better, the story is over.
Andrew you are insinuating 2 things I have never claimed nor am interested in.
1-I am not talking about colorimetry. I want to reproduce the scene as I saw it. But to me this is far different from sheer arbitrariness. I just don't buy it.
2-I don't want to urge anybody to use my method. If your preferred rendering of that scene is say like the one resulting from the AWB, you're welcome.
All I wanted to do is for once give back a little to this forum where I have learned so much.
> Neither of us can provide anything scientific to say our perception of either the scene or the capture is more accurate than the other.
No we can't. The kind of science that might apply here might be something like this: I should gather xx naturalistic painters on my porch, have them look at the scene, then at the images on my calibrated screen, and have them select the one they found most natural. Until I get that done, I will proudly point to Tim Lookingbill (post #4) who picked the same image as I did even if he was not at the scene.
Good light - and true color :-)
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1-I am not talking about colorimetry. I want to reproduce the scene as I saw it.
That is a perceptual phenomena. The end result of the excitation of photoreceptors followed by retinal processing and ending in the visual cortex. We define colors based on perceptual experiments.
As I said, we can both be at the same scene and disagree about what we perceive. Colorimetry is the yardstick in which we could attempt to say which person and subsequent capture is as you or the camera "saw it", otherwise this is no more accurate than an assumption.
The kind of science that might apply here might be something like this: I should gather xx naturalistic painters on my porch, have them look at the scene, then at the images on my calibrated screen, and have them select the one they found most natural. Until I get that done, I will proudly point to Tim Lookingbill (post #4) who picked the same image as I did even if he was not at the scene.
You mean Tim and you agree about a preferred rendering? It says nothing about accuracy, my original point.
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In my o.p. I did not ask which rendering anybody preferred, but which one anybody found most natural, and that was the question Tim answered. It says nothing about which rendering he preferred.
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In my o.p. I did not ask which rendering anybody preferred, but which one anybody found most natural, and that was the question Tim answered. It says nothing about which rendering he preferred.
The original quote I see is:
I had a bright moment and have figured out how to set the natural (visually correct) white balance at shooting time. But before I reveal the secret, you have to guess:
Visually correct is what you prefer. I've said that now more than once. It has nothing to do with the numbers you set on the camera, see on the back of the LCD or in reality, what you remember you saw when you took the capture. OK, done.
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In my o.p. I did not ask which rendering anybody preferred, but which one anybody found most natural, and that was the question Tim answered. It says nothing about which rendering he preferred.
The illumination of the scene appears to be quite blue, perhaps most of it is coming from the skylilght, which could easily have a CCT of 10000K even towards dusk. One can estimate the illumination by looking at the roof of the structure covered with snow.
The WB with a CCT of 10000K gives the most neutral result and it is not surprising that it was favored by several observers.
(http://bjanes.smugmug.com/Other/CCT-Examples/i-MwtZbNZ/0/O/CCT_Composite.png)
One can open one of the images in ACR and white balance on the roof as shown. This could be used as a starting point from which adjustments to obtain the best match to the perceived scene.
(http://bjanes.smugmug.com/Other/CCT-Examples/i-5pr36bK/0/O/ACR_WB.png)
Regards,
Bill
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The original quote I see is:
Visually correct is what you prefer.
Hi Andrew,
I disagree with your interpretation of the OP's quote. The way I interpret Hening's revelation, he wants a reasonably close representation of what he saw at the time of shooting encoded as "As shot". Period. Where that initial white balancing will ultimately lead to is not yet decided. That seems to be a perfectly valid approach, because it provides a much more reasonable starting point than we could get from an "Auto" setting or from our memory. It could well be something close to 5500K. As a minimum it would probably reduce a significant percentage of magenta sunsets (sunsets are usually not magenta), and produce a somewhat more realistic looking thumbnail in the Raw file.
Cheers,
Bart
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I think that the images presented weren't the best to prove or disapprove anything. Aesthetically not at all pleasing. Better images might have helped? Hening's idea isn't going to become popular mainly because the lcd on a camera isn't calibrated, too small and notoriously difficult to see. An "accurate" WB as Andrew points out is meaningless. If there was only one small flaw in Henings idea then it would be possible to argue a good case but there is more than one so it isn't going to happen? Like 99% of Heureka - I think he means eureka - moment's ....it is doomed to failure.
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Bill, Setting the color temp in my camera on the d700 and d800e do nog give identical result. That is why i stopped working with a set colottemp, i just use AWB and where possible a CCP image or more if light situation changes.
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WB can get quite philosophical. Do you want each color rendered as closely as possible to how the physical scene was (i.e. a spectrophotometer would have as similar readings in the original scene vs the recreation as possible)? Do you want to remove the spectral bias caused by the scene illumination? Do you want to replace it by the illumination used in the room where the image is to be viewed? Do you want image "white" to match passpartout white?
I use the WB picker on something perceived as "white", then push the sliders until I see something that I like on screen, then do a few iterations of prints until I am happy (lr softproofing is only slightly helpful to me). I also have profiles for my camera, displays and printer/paper.
-h
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Hi Bart
> Where that initial white balancing will ultimately lead to is not yet decided.
I must admit though that my intention is to leave it there - I have nothing better to come up with. Every change would be merely arbitrary.
Hi Stamper
> Aesthetically not at all pleasing.
Agreed! I had no artistic ambition with the image. The scene has what I needed: a tricky WB - that's all.
> I think he means eureka
Indeed it turns out that is the english spelling. The original greek word contains a little diacritic mark which is the equivalent of a leading "h", and so the quote is spelled in my native german.
> the lcd on a camera isn't calibrated, too small and notoriously difficult to see.
All sadly true. Further more, the Canon in-camera jpeg is over-steepened in contrast and over-saturated in colors. If memory serves me, my Nikon D200 was more civilized.
But alas - we have to live with the tools we can get...
And I still think that despite all of the above, my "method" can do something I have not found elsewhere.
Hi Christmas Dwarf!
My WB philosophy: I want to reproduce the scene as I perceived it at shooting time. That is not a colorimetric representation, but the same, biased by human vision, herein the AWB of our brain - and the limits of that AWB. I do not want to remove the spectral "bias" caused by the illumination - that is the approach which is valid for catalog shooting and art reproduction. To me, this "bias" is part of the "subject" I want to reproduce. At shooting time, I can not take into account the illumination in any room.
I, too, have profiles for my camera and my monitor. For printing I use a service which has good profiles for their printers. My passe-par-touts are black.
Good light - and true color :-)
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My WB philosophy: I want to reproduce the scene as I perceived it at shooting time. That is not a colorimetric representation, but the same, biased by human vision, herein the AWB of our brain - and the limits of that AWB. I do not want to remove the spectral "bias" caused by the illumination - that is the approach which is valid for catalog shooting and art reproduction.
The WB model we use with our digital cameras works well for relatively high levels of illumination and with illuminants whose CCT does not deviate too far from daylight. At low levels of illumination, the Purkinje effect (http://en.wikipedia.org/wiki/Purkinje_effect) occurs and this is not taken into account by the usual WB algorithm. Also, chromatic adaption is never complete with illuminants much below 3000K or thereabouts. Candlelit scenes will always appear reddish.
Because of these complications, your empiric approach is necessary at low levels of illumination and with low CCT illuminants. Some have criticized your use of the camera LCD for this purpose but have offered no solution other than to adjust the WB after the fact using your memory of the scene. However, memory is imperfect. Another approach would be to use live view and a field monitor such as this (http://www.bhphotovideo.com/c/product/786655-REG/Marshall_Electronics_V_LCD70XHB_HDMIPT_SL_7_Field_Camera_Top.html). I don't know if this model can be calibrated. If so, one would have to decide on what luminance and CCT to use for the white point.
Anyway, thanks for a useful post that has led to some interesting discussion despite some naysayers. As per an old saying, no good deed goes unpunished. :)
Regards,
Bill
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Hi Bill
Thank you for your encouragement. I am happy to read that you find my post useful. As said, I felt that for once I might be able to give back a little to this forum, where I find myself on the asking side for the most. Almost all my education in digital photography has gone on here.
As for a field monitor: Thanks for the link! I would order this one at once if id did not weigh 860 grams - and not specified if that includes batteries - or does 'battery adaptor' mean that one needs a wall socket ??
I have long wondered why nobody makes an adaptor to use the iPhone for this purpose. That weighs only 100 grams...
Anyway - thanks again -
and a happy new year to all of you!
Hening
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Interesting read, Hening.
Don't know if anyone's tried this and arrived at the same results, but I've noticed processing a thousand or so Raws shot under various non-pro/non-studio light conditions after setting WB in ACR clicking on a WhiBal card target included in the scene, I can adjust the Temp/Tint sliders to noticeably change the overall color cast of the image with very little if no change to the R=G=B readouts on the WhiBal card gray portion barring any noise sampling point issues.
What does that say about scientifically setting accurate WB according to a spectrally flat target?
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As for a field monitor: Thanks for the link! I would order this one at once if id did not weigh 860 grams - and not specified if that includes batteries - or does 'battery adaptor' mean that one needs a wall socket ??
I have long wondered why nobody makes an adaptor to use the iPhone for this purpose. That weighs only 100 grams...
Anyway - thanks again -
and a happy new year to all of you!
Hening
Helicon does make an ap for Android devices (Helicon Remote (http://www.heliconsoft.com/heliconremote.html)) that is primarily for focus stacking but it might be used to preview the camera image. An iPhone/iPad version is planned, but it will only be able to communicate with the camera via WiFi since the Apple system is closed and the necessary WiFi transmitter is expensive. For Nikon, Control my Nikon (http://www.controlmynikon.com/index.html) enables tethered operation and is very inexpensive. Unfortunately it requires a PC or Mac. Perhaps one could use one of the small notepad PCs. If anyone has any experience with the above, please share your findings.
Regards,
Bill
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That is really good news! The Google Nexus 7 looks affordable and not too heavy (12 ounces, 340 grams). I am investigating concerning the connectivity. Both the tablet and the camera have Micro USB sockets, but I can not find a cable that has micro USB male on either end. I am not familiar with WiFi. Can one set up a connection just between the camera and the tablet without a router and outside Internet coverage?
Good new year! - Hening
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Kinon from the Helicon forum has kindly pointed me to this adapter cable:
http://www.usbfever.com/index_eproduct_view.php?products_id=2447
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The magenta-green axis
I am aware of that that this is to be considered. But how much does the daylight change during the day along this axis? In another thread on this forum, which I fail to retrieve right now, I was told that it changes very little, and have since set the Tint in the raw converter to zero.
While the magenta/green axis doesn't change a lot in normal blackbody radiators, the response of the magenta/green by a sensor can. ... To have zero Tint is likely to be wrong in 90% + cases...
The canned settings for Daylight, Cloudy and Shade in ACR are indeed based on a fix value and offset for Tint which is suggested to be +10, thus adding some magenta neutralizing the slight green cast of the standardized D illuminants relative to the Planckian locus (while the so-called Daylight locus is a tad of 0.003 delta-uv above the blackbody curve in the CIE xy chart).
ACR Daylight: 5500 /+10, Cloudy: 6500 /+10 and Shade: 7500 /+10
Aside from possible deviations with the chromaticities of natural daylight, we have seen this +10 value to be a reasonable assumption for one camera, whereas it was found to be persistently off target and should be more -10 for another camera (referring to different camera models).
Hence there can be a need to calibrate the ACR arithmetic to the camera/sensor, for example by creating own Presets in ACR for the various Temperatures but with a different offset for Tint. Or, by just having this Tint offset in mind when starting editing with camera-AWB as shot.
Adjust to taste, warmer or colder, is typically easier when having green/magenta already somewhat in the ballpark.
Peter
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Thank you for this info, Peter. - Would this magenta-green calibration of the camera not be automatically included in a custom camera ICC or DNG profile?
Concerning an external camera monitor to go with the Helicon Remote software: The Samsung Galaxy Note weighs only 180 grams (6.3 ounces) and seems large enough.
Good light!
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Thank you for this info, Peter. - Would this magenta-green calibration of the camera not be automatically included in a custom camera ICC or DNG profile?
The DNG profile editor allows to do so in the Color Matrices pane (-> white balance calibration),
however, from what we can tell such deviating offset with Tint is not already considered by Adobe in the profiles as shipped.
Best regards, Peter
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What hasn't been addressed in this discussion that I'ld like touched upon is what any given white balance (aesthetically or technically accurate according to color science and spectra data) does to individual colors that aren't included as part of the color target used to produce a DNG profile or regular canned ones like Adobe Standard.
Take for instance this portrait I came across linked to in a Photo.net Lighting forum thread:
http://www.flickr.com/photos/vimages/8298075493/in/pool-1773207@N23/
Pinky caucasian skin syndrome using any number of flash or bright noon daylight. This happens quite often in similar shots among quite a few photographer's galleries I've come across online. And what seems to fix this in my shots that exhibit this is to add green to the white balance or use HSL to fix it but then the reds/oranges suffer for other image elements not exactly close to this skin color.
Just wonder if a study on perception of how much WB influences some colors over others has been conducted.
I realize another way to fix this is on an individual color by color basis tweaking the DNG profile recipe in Adobe DNG Profile Editor. That can get pretty cumbersome and sometimes when doing this it can introduce posterization if you get too refined the closer that pinky skin gets into other reds and oranges that look correct on other image elements.
There's also the issue of adaptation in whether one sees pinky skin appear orangish tan that has nothing to do with the appearance of WB but rather tweaks to the color table I've demonstrated in the two caucasian skin appearances between a custom dual illuminant profile and Adobe Standard on the same image below.
Here's an experiment...First look at the DNG Profile version for a while and note how much yellow appears in the skin compared to the pinky skin flickr portrait above, then close custom DNG Profile image and stare a bit at your 6500K display white a bit and then go back and first stare at the Adobe Standard version for a while and then quickly switch to the custom DNG Profile. For me when doing this, the DNG Profile now looks more pink than it did before.
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Hi
--this is not a reply to Tims post just above (#41), but to Peter_DL (#40) --
Peter I don't quite understand you. What I had in mind was: If the magenta offset is a constant for any particular camera, rather than something that changes during the day - will it not automatically be corrected if one makes a custom profile for that camera? Just any reasonable profile?
The manual of Raw Therapee (version 4.0.9, page 31) has a table for temp and tint values for neutral rendering for a number of cameras. The tint values range between about 0.9 to 1.1. I wonder how this relates to your figure of plus-minus 10.
Kind regards - Hening
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What I had in mind was: If the magenta offset is a constant for any particular camera, rather than something that changes during the day - will it not automatically be corrected if one makes a custom profile for that camera?
When running the Chart Wizard of the DNG Profile Editor, the ColorChecker chart as shot gets automatically white-balanced (based on the second brightest neutral patch i.e. light gray), before the Hue/Sat.-corrections are built per color patch. However, the Temp/Tint adjusts from this preceding white balance do not flow directly into the profile e.g. by ruling white balance calibration in the Color Matrices pane.
It would not necessarily be wise to have this auto-included at this stage, while the software cannot differentiate between the two effects:
a.) the variance of natural occurring daylight perpendicular to the Daylight curve or Plackian locus (as shot).
b.) a systematic offset with Tint introduced by the camera/sensor.
Anyway I was referring to DNG profiles and the DNG Profile Editor.
ACR does not take ICC/DCP profiles. No idea what related profiling software does in this respect.
The manual of Raw Therapee (version 4.0.9, page 31) has a table for temp and tint values for neutral rendering for a number of cameras. The tint values range between about 0.9 to 1.1. I wonder how this relates to your figure of plus-minus 10.
Interesting though !
Best regards, Peter
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Thank you. So an ICC camera profile (which I have in use) may be different.