Reds

[jrista]

something else to think of, we are unable to remember colors. Our brain is just no wired that way. There are some exceptions to the rule, but they are few and far between. . . I work with colors in my daily job and have learned that my memory tricks me often and now have Pantone books in strategic locations.

pierre

I'd like to see the scientific papers that explain how and why this could be true. I remember colors quite clearly myself for a good while. It is only after years as memories naturally fade, and our recollection of all details, not just color, diminishes. There have been a few papers written on the subject of memory and color, and the science demonstrates that we actually remember things better when they are in color, particularly NATURAL colors, vs. when they lack color, or are artificially colored.

In that context, I can easily understand the OP seeing the red as his images are being replicated by LR, and not remembering the color of the real flowers that way. The real flowers obviously have natural color, whereas the rendition of those flowers in LR is less natural. That discrepancy, and the OP's sensation of it, more than anything else here, is absolutely real. The closer the OP can get his flowers to render like the real natural color, the less he will feel that something is off.

There are limitations with rendering realistic color when it comes to digital photography. For one, silicon is extremely sensitive to red and infrared light. To attenuate this sensitivity, camera manufacturers use IR cutoff filters that have a gradual incline in the passband as it enters the reds. This limits how well we can naturally resolve reddish colors. Further, most computer screens are 8-bit sRGB, and the sRGB gamut is a rather limited one. It does not allow the greatest extent for deeper reds. Combine that with potentially limited or incorrect recording of reds by the camera sensor, especially for brighter colors that may be close to the non-linear shoulder of the sensor's response (i.e. closer to the clipping point of the signal), and getting realistic reds can be very difficult.



Calibration with a color checker card is one way to improve results. I wouldn't call it a panacea, but it can help when your working with extreme colors. Keeping your exposure in the linear range of the sensor will also help. That usually means reducing the exposure a little bit, which might hurt shadow detail if you have any...but it will preserve more accurate colors at the high end of the signal.

Manual tweaking of colors with the color channel sliders in LR can do a lot, but it works best if all of your channels are sufficiently below the clipping point of the signal. You need some headroom to shift colors around without unnatural casts appearing.

 

[martti]

Outdoors, it's nearly useless if you don't re-shoot the card every other minute as the lighting is so quick to change (sun moving, clouds and moisture changing the wb).

The spectrum of sunlight is absolutely constant - by definition it is a black body radiator with CRI 100. Clouds are effectively color neutral except in major pollution zones, and the scatter from the sky serves to alter the color temperature of 'daylight' by increasing the blue bias, but it doesn't change - even at night, the sky is the same color of blue, as you can see if you take long-exposure photos under a full moon. The CRI is always 100, even at sunset.

The CCP/Macbeth chart is all about profiling the sensor's relative luma/chroma offsets, it is sensitive to low-CRI spectra such as an LED with a chunk of yellow missing, but the response is effectively immune to color temperature over the range of values you'll get under what we call 'daylight'. You can build one CCP profile for each camera in daytime conditions - sunny, cloudy, foggy, makes no difference - and for any other photo you simply need to fix the WB with a gray reference or one of the standard values. There is no need to wave a CCP in front of every scene. There's a reason your cameras have a WB control and a picture profile called "Neutral", but not one called "Sunny Neutral". You're adjusting entirely different things.

Hm. Theoretically maybe so.
In practice you see the color of the light change when clouds pass...there is less blue coming from the sky above if there is a white cloud above. If the cloud is in front of the sun and you have blue sky above, of course you get more blue light in. If you are in a forest, the relative amount of green sieving through the foliage as well as its hue varies according to sunlight. Shiny green leaves look blue when they reflect the blue sky above.

Theories are there to simplify reality so it becomes accessible to rational thinking.
Which is good, I suppose.

 

[DFM]

Hm. Theoretically maybe so.
In practice you see the color of the light change when clouds pass...there is less blue coming from the sky above if there is a white cloud above. If the cloud is in front of the sun and you have blue sky above, of course you get more blue light in. ...

... which changes the color temperature but does NOT degrade the CRI. It's a white balance effect only. If it wasn't, then the way the WB pickers operate in Lightroom or Photoshop would be invalid - we would have to apply a different spectral LUT for every Kelvin value.

If you were mixing daylight and artificial light (e.g. in a stadium), or shooting through a strong colored filter, then you would be introducing discrete spectral peaks and troughs, reducing the CRI, and changing the calibration profile.

 

[martti]

Hm. Theoretically maybe so.
In practice you see the color of the light change when clouds pass...there is less blue coming from the sky above if there is a white cloud above. If the cloud is in front of the sun and you have blue sky above, of course you get more blue light in. ...

... which changes the color temperature but does NOT degrade the CRI. It's a white balance effect only. If it wasn't, then the way the WB pickers operate in Lightroom or Photoshop would be invalid - we would have to apply a different spectral LUT for every Kelvin value.

If you were mixing daylight and artificial light (e.g. in a stadium), or shooting through a strong colored filter, then you would be introducing discrete spectral peaks and troughs, reducing the CRI, and changing the calibration profile.

Hm. Theoretically so. It just so happens that when you take pictures of a person while you are walking with her in the shades of trees and bushes you might get her face all green if you do not watch out. Green is not a temperature, it is a color or a hue. You can take pictures of green things under various color temperatures and they remain green. But if the light falling on your model's face is green (sifted through the foliage) no amount of temperature adjustment will ever get it back to normal skin color again. Now you have to do something to take the green hue away. Like a fill-in flash if you do not mind the artificial look it gives to your shot.
Or locally adjusting the amount of green in PP.

If you have a grey card in your shot next to the face and you smartly use the color picker to put your color balance right, you end up with magenta trees. If that's what you like, OK.

You see?

 

[martti]

something else to think of, we are unable to remember colors. Our brain is just no wired that way. There are some exceptions to the rule, but they are few and far between. . . I work with colors in my daily job and have learned that my memory tricks me often and now have Pantone books in strategic locations.

pierre

I'd like to see the scientific papers that explain how and why this could be true. I remember colors quite clearly myself for a good while. It is only after years as memories naturally fade, and our recollection of all details, not just color, diminishes. There have been a few papers written on the subject of memory and color, and the science demonstrates that we actually remember things better when they are in color, particularly NATURAL colors, vs. when they lack color, or are artificially colored.

In that context, I can easily understand the OP seeing the red as his images are being replicated by LR, and not remembering the color of the real flowers that way. The real flowers obviously have natural color, whereas the rendition of those flowers in LR is less natural. That discrepancy, and the OP's sensation of it, more than anything else here, is absolutely real. The closer the OP can get his flowers to render like the real natural color, the less he will feel that something is off.

There are limitations with rendering realistic color when it comes to digital photography. For one, silicon is extremely sensitive to red and infrared light. To attenuate this sensitivity, camera manufacturers use IR cutoff filters that have a gradual incline in the passband as it enters the reds. This limits how well we can naturally resolve reddish colors. Further, most computer screens are 8-bit sRGB, and the sRGB gamut is a rather limited one. It does not allow the greatest extent for deeper reds. Combine that with potentially limited or incorrect recording of reds by the camera sensor, especially for brighter colors that may be close to the non-linear shoulder of the sensor's response (i.e. closer to the clipping point of the signal), and getting realistic reds can be very difficult.



Calibration with a color checker card is one way to improve results. I wouldn't call it a panacea, but it can help when your working with extreme colors. Keeping your exposure in the linear range of the sensor will also help. That usually means reducing the exposure a little bit, which might hurt shadow detail if you have any...but it will preserve more accurate colors at the high end of the signal.

Manual tweaking of colors with the color channel sliders in LR can do a lot, but it works best if all of your channels are sufficiently below the clipping point of the signal. You need some headroom to shift colors around without unnatural casts appearing.

Our sensory system is not only analog but relative as well. It has not evolved to give exact values aroud certain zero point along graduated axes but rather bright-dark, warm-cold, pressure-lightness etc. Rough and ready is what is needed for survival!

Our vision gets calibrated according to the ambient light so that we see green as green and red as red whether it is sunlight or candlelight around us. In moonlight, however our cones cease to function and we only see in BW. that's why all the cats are grey in the dark. They do not change color but our machinery or perception changes the way we see them. That's because rods are more sensitive to light...it is better seeing BW than not seeing anything at all.

All this is very basic physiology known for decades now.
We cannot remember the amount of light, we cannot know the weight of a bag of grain unless we either weigh it or have a bag of known weight at hand so we can tell if the other one is lighter or heavier. We cannot asses the volume of a sound and only very few of us have perfect pitch...they can tell whether a note is a C or a C# just by the ear...for some reason a lot of native Mandarine Chinese have perfect pitch but nobody knows why.

Mathematics is basically music with ice cubes in it.

Color vision is very interesting as well. For instance whales have lots of sensors for blue light on their retina.
That's because they have dwelled in the oceans for so long. Seals, on the other hand who are close relatives to bears, have similar retinal sensors as their terrestial cousins.

Women (some of them) have two different variations of red sensors on their retinae.
Because their speciality was to judge whether a fruit was at its optimum ripeness for picking.

The point is: Do not argue with your wife about the color balance of the pictures you have taken of her.
She is better equipped than all the Adobe males bunched together in this very matter!

 

[martti]

And still another point: A flower does not have a natural color. this is a nonsensical statement. The pigments in a flower reflect and absorb the spectrum (=the combination of different wavelengths) of the light that is falling on them...and not only that because we only talk about the what we can see which is a very limited part of the spectrum that we antropomorphically call 'visible light'.

Of course a bee or a snake would define 'visible light' differently...

 

[jrista]

And still another point: A flower does not have a natural color. this is a nonsensical statement. The pigments in a flower reflect and absorb the spectrum (=the combination of different wavelengths) of the light that is falling on them...and not only that because we only talk about the what we can see which is a very limited part of the spectrum that we antropomorphically call 'visible light'.

Of course a bee or a snake would define 'visible light' differently...

Within the context of human vision, which sees wavelengths from about 750nm through 380nm (the visible spectrum, as it is scientifically defined, and in contrast to the near infrared or near ultraviolet spectrums that bound it), flowers absolutely do have a natural color. It is human vision we are talking about, not bee or snake vision.

Natural color is colors that occur in nature, and are "appropriate" for the given subject, within the context of human vision and experience. In contrast, a total lack of color would be grayscale or monochrome of some kind. False color would be when colors do not conform to the natural distribution (i.e. green flowers with red stalks and leaves.)

As I said, there have been scientific studies on this subject.

 

[martti]

fail

No. No 'natural color' but just a part of the spectrum of ambient light absorbed and reflected and observed with the human visual system. Your thinking is wrong.
Get acquainted with the science of vision before you make arguments about it.

 

[jrista]

Re: fail

No. No 'natural color' but just a part of the spectrum of ambient light absorbed and reflected and observed with the human visual system. Your thinking is wrong.
Get acquainted with the science of vision before you make arguments about it.

Your entirely missing the point, but that isn't surprising on these forums. Why not do a couple searches and read some of the articles I am talking about? Your talking spectrum, I'm talking psychology. Missing the point. (Why does everyone around here miss the point 99% of the time? Meh.)

 

[danski0224]

Has anyone posting in this topic tried UniWB?

I have not yet, but would like to.

 

[jrista]

Has anyone posting in this topic tried UniWB?

I have not yet, but would like to.

I tried UniWB on my 7D a long time ago. I found it unnecessary, as the white balance setting in the camera is simply metadata added to the image. It does not actually affect the exposure of individual green pixels, since all in-camera white balance occurs after the sensor is read out. The only potential benefit with UniWB is that it might prevent the camera from overexposing one channel if your using some kind of automatic or semi-automatic exposure mode (P, Av, Tv) that relies on in-camera metering, but that is it. It does not actually change white balance, since white balance in RAW is simply a bit of metadata and some math.

 

[danski0224]

The more accurate RAW histogram is why I want to try it.

 

[Marsu42]

The more accurate RAW histogram is why I want to try it.

You gotta be kidding me - unless you are on 1d why fuss around with a hack if Magic Lantern gives you an actual raw histogram, all nice with even an estimation of how much dr was clipped?

 

[jrista]

The more accurate RAW histogram is why I want to try it.

You gotta be kidding me - unless you are on 1d why fuss around with a hack if Magic Lantern gives you an actual raw histogram, all nice with even an estimation of how much dr was clipped?

Totally agree here...use ML for the RAW histogram. Much better than UniWB.

 

[danski0224]

Unfortunately, ML doesn't work on 1D bodies.

 

[martti]

Re: fail

No. No 'natural color' but just a part of the spectrum of ambient light absorbed and reflected and observed with the human visual system. Your thinking is wrong.
Get acquainted with the science of vision before you make arguments about it.

Your entirely missing the point, but that isn't surprising on these forums. Why not do a couple searches and read some of the articles I am talking about? Your talking spectrum, I'm talking psychology. Missing the point. (Why does everyone around here miss the point 99% of the time? Meh.)

WHo do you think you are fooling?
You do not know what the point is so you do not have one.
Psychology...give me a break. You know nothing about it!

 

[jrista]

Re: fail

No. No 'natural color' but just a part of the spectrum of ambient light absorbed and reflected and observed with the human visual system. Your thinking is wrong.
Get acquainted with the science of vision before you make arguments about it.

Your entirely missing the point, but that isn't surprising on these forums. Why not do a couple searches and read some of the articles I am talking about? Your talking spectrum, I'm talking psychology. Missing the point. (Why does everyone around here miss the point 99% of the time? Meh.)

WHo do you think you are fooling?
You do not know what the point is so you do not have one.
Psychology...give me a break. You know nothing about it!

Ah, bluster. The hallmark of the man without an argument. Nice meeting you, martti. You'll fit right in here. Your a pea in the pod.

 

[bholliman]

That doesn't change my opinion 'bout the op's "red" shot though, with proper handling of the 6d it shouldn't be necessary to use a color checker to avoid the nuclear holocaust look of those flowers.

Looks like harsh lighting- could have used a shade.

I would bet that the image as a whole is overexposed. For sure, the red channel is all the way right. I would guess that the exposure compensation should have been at least -1 if not -1.5.

A circular polarizer would have helped a great deal.

The image as-is might look decent in B&W. I have a few that look bad in color but great in monochrome.

I hadn't checked this thread in awhile and was surprised to see it had grown to 3 pages.

I know this picture isn't very good. It was one of a few quick shots I took while walking through the garden with my wife during a short stop while traveling. Yes, its full, late afternoon sun. Not only is the light less than ideal for good flower photography, but I should have stopped down further so the fountain behind the tulips was not so out of focus. Since we didn't have much time, and my wife little patience for photography I just took a few quick unplanned shots. If this garden were closer to home, I would have shot it in better light and more carefully composed the shot.

I used it as an example since I've seen these messed up reds before. Always in full sunlight, so maybe its just poor technique on my part. That said, shouldn't I be able to get good color rendition in full sun?

Looking at the raw histogram in Lightroom when I reset it, the exposure looks OK and I don't see major problems with the histogram. None of the color channels have highlights clipped. Blue is clipped in the shadows.

I can make the RAW file available to anybody who wants to play with it, but not sure how to transfer a file this large.

BTW, the settings for the shot are:

ISO 100
1/320
f/5.0

 

[danski0224]

I used it as an example since I've seen these messed up reds before. Always in full sunlight, so maybe its just poor technique on my part. That said, shouldn't I be able to get good color rendition in full sun?

I would try a custom white balance.

This is easy to use, inexpensive for photography gear and straightforward: www.digitalphotographykits.com

I have noticed that it really makes a noticeable difference. I haven't used it much, but the results I get are telling me that I need to make the effort to use it more.

Also try a circular polarizer- plenty of light in full sun.

Digital cameras have UV filters, so I don't know if there are additional issues any possible UV reflection from the flowers requiring an additional UV filter.

You may need to dial in some negative exposure compensation. Try it, it can't hurt.

 

[bluemoon]

something else to think of, we are unable to remember colors. Our brain is just no wired that way. There are some exceptions to the rule, but they are few and far between. . . I work with colors in my daily job and have learned that my memory tricks me often and now have Pantone books in strategic locations.

pierre

I'd like to see the scientific papers that explain how and why this could be true. I remember colors quite clearly myself for a good while. It is only after years as memories naturally fade, and our recollection of all details, not just color, diminishes. There have been a few papers written on the subject of memory and color, and the science demonstrates that we actually remember things better when they are in color, particularly NATURAL colors, vs. when they lack color, or are artificially colored.

In that context, I can easily understand the OP seeing the red as his images are being replicated by LR, and not remembering the color of the real flowers that way. The real flowers obviously have natural color, whereas the rendition of those flowers in LR is less natural. That discrepancy, and the OP's sensation of it, more than anything else here, is absolutely real. The closer the OP can get his flowers to render like the real natural color, the less he will feel that something is off.

There are limitations with rendering realistic color when it comes to digital photography. For one, silicon is extremely sensitive to red and infrared light. To attenuate this sensitivity, camera manufacturers use IR cutoff filters that have a gradual incline in the passband as it enters the reds. This limits how well we can naturally resolve reddish colors. Further, most computer screens are 8-bit sRGB, and the sRGB gamut is a rather limited one. It does not allow the greatest extent for deeper reds. Combine that with potentially limited or incorrect recording of reds by the camera sensor, especially for brighter colors that may be close to the non-linear shoulder of the sensor's response (i.e. closer to the clipping point of the signal), and getting realistic reds can be very difficult.



Calibration with a color checker card is one way to improve results. I wouldn't call it a panacea, but it can help when your working with extreme colors. Keeping your exposure in the linear range of the sensor will also help. That usually means reducing the exposure a little bit, which might hurt shadow detail if you have any...but it will preserve more accurate colors at the high end of the signal.

Manual tweaking of colors with the color channel sliders in LR can do a lot, but it works best if all of your channels are sufficiently below the clipping point of the signal. You need some headroom to shift colors around without unnatural casts appearing.

Sorry, no papers, but here's what I have read and what seems to be going at my work.
As explained by martti, our vision system is relative rather than absolute. When we try to memorize the colors, we mentally compare them to something we know or describe them as a warm red, darker than something else and so on. We are creating a reference point that can be used for later recognition.
try this, have somebody make you 10 squares of various red color. pull one out of the hat and mark the back. Look at the color and try to memorize it without rationalizing its hue, saturation or brightness. Put it back in the hat and have the person helping you lay them out on the table next day. See if you can pick the right one. If you concentrate on the color alone without making mental references to it being dark, light, warm, cold and so on, it is very unlikely that you'd be able to pick the right square.

let me know how it goes!

pierre