Why it's not a good idea to calibrate a display to a 5000K color temperature.

Discussion in 'Digital Darkroom' started by tim_lookingbill, Sep 27, 2009.

  1. I've never calibrated my display to a 5000K color temperature. I've always set it at native or 6500K which usually is the same thing. My 2004 iMac's LCD panel has aged to the point it's native color temperature is now at 6000K. It's still, compared to 5000K, quite neutral looking, just a smidge less blue than 6500K.
    I've often wondered why there are those that insist on calibrating and editing images using a 5000K display, so I decided to find out for myself by comparing the different color temperatures. Surprisingly I found under 5000K I had to extensively edit hue and saturation in 100's of landscape shots that were OK under 6000K and 6500K. Under 5000K cool colors lost their vibrance and skintones took on a dull looking yellow. I even waited for adaptation to kick in and it didn't.
    I started investigating the subject of color constancy to find an answer as to why this occurs. I discovered through observation that displays don't have the same spectral characteristics and affect on our eyes compared to viewing prints under let's say a full spectrum, neutral light source like the Solux lamp. This light retains the appearance of hue/saturation in prints despite its dull yellowish cast because of it's inherent ability to bring out the spectral reflectance of the ink and the paper substrate.
    An LCD can't do this or at least the calibration software isn't building the proper tables to compensate the hit to hue/saturation in color managed images enough so to make the image look correct to the point no further edits are required.
    Below shows shots taken with my Pentax K100D DSLR of my iMac calibrated to 6500K, 6000K(native) and 5000K using Eye-One Display in order to demonstrate this optical phenomenon. The fourth image shows the overall neutral feel the Solux lamp imbues to a scene due to its ability to bring out different spectral properties contained in various white/neutral objects despite its slight yellow cast on certain objects similar to the white of the 5000K display. Notice the 5000K display seems to have a yellow filter over the entire screen where as the scene lit by the Solux lamp doesn't. This is why 6500K is the ideal color temperature to calibrate to and edit under. It just looks neutral.
    Just FYI for those that ever wondered about this. Your thoughts and opinions are welcome.
    00UbBI-176113584.jpg
     
  2. What color of paper are you printing on?
    Run a sheet of newsprint through your inkjet printer, and you might see the difference. This is probably a bad example, but here are two photos.
    00UbE6-176131684.jpg
     
  3. Same image on different types of paper. Match the white balance to what's defined as white on your chosen output. Newsprint will be yellower. The newsprint used here will be ordinary scrap unbleached paper.
    I included the tracing paper because it used to be used in paper layouts of ads. Although, I can't think of a time that I've seen images printed on the stuff. It was usually text or pencil mark-ups. But, you'll see that color of paper rides in between the contemporary brightened papers and newsprint rag.
     
  4. Here's the pic, unadjusted for the types of paper. You may be using papers that are built to match what you see on a screen. Before, it was up to you to do the matching.
    00UbED-176133684.jpg
     
  5. If you flip your display over to 5000K, you will see a stronger difference between the three papers. The typing paper will appear slightly blue; newsprint rag will be yellow; the tracing paper will be close on to white, but a touch yellow.
     
  6. 5000K is an undefined target (its a range of colors). That’s why when you talk about a color in degrees kelvin, its useful to use CCT (correlated color temperature) because again, its a heck of a lot of different color possibilities.
    5000K (better defined D50) is fine IF the screen to print match. Sometimes it does. Depends on the illuminate used to view the prints. D50 is no more or less right or wrong than any other target calibration aim point. If it doesn’t match the viewing conditions, its wrong. If it does, its right. You can take several calibration packages, the same instrument and ask them to calibrate to 5000K, they will not be the same. They should be, but they in all llikelihood will not.
     
  7. I set my CRT to 5000k and get very good screen to print match for prints to be viewed under tungsten light...even though the tungsten light is closer to 3000k.
    My laptop LCD screen doesn't do so well changing much from the native white point, so I set the laptop to 6500k.
    I also keep a calibration for 6500k for viewing video on the computer...
     
  8. I agree with Andrew's points about the look of 5000K. I'm using the original i1 Display and now that I have to force the LUTs in my iMac to render 6500K, i1Matches rendition pulls back the green channel slightly which makes sense because of the green spike inherent in fluorescent panels. Frankly I'm glad Eye-One does this because I never realized how green the native WP of my display really was. But I'm afraid the matrices that are built reflecting this slight tweak in previews of color managed images give a slightly desaturated appearance to skintones, but it might be due to the added bluishness or adaptation which I constantly fight. Setting my display to 5000K doesn't fix this for me at least.
    John it's clear to me that you are seeing things differently under your brand of neutral light you view prints under or maybe your camera is set different from mine. Your images posted here are coming across way too blue. This is not what I see under the 4700K/D50 Solux. The Solux does have a slightly but noticeable warm yellowish cast, but it can only be seen on certain substrates that reflect this. I was hoping I got that across in the fourth shot showing the neutral surfaces. I'll provide some shots of actual prints of the color targets shown in the iMac color temp captures to show you that, though your point about the properties of different papers is true, it's just that I don't see what you are seeing. See image sample below.
    But really my point about all this wasn't to demonstrate nailing the look of these color temps but more about showing how it induces the user (myself included) into editing their digital camera images when it isn't necessary. The color targets don't look all that different between the color temps, but I found most of my real world images taken of outdoor scenes with AutoWB was just too butt ugly under 5000K. That's just way too much additional work. The Bridge preview of the two outdoor images show how 5000K dulls all those greens and jade colors which I'll have to edit back in if I calibrated my iMac to 5000K. Those are straight out of the camera shots and I like how they look under 6500K not 5000K.
    Mind you in my capturing what I've posted here the results are never quite as accurate coming straight out of my camera and I have to edit all of these images to get them to look as my eyes see the scene.
    00UbMf-176203584.jpg
     
  9. Here's something else I found that's going to leave you scratching your head.
    When I switch my display to the 5000K profile and accept the drastic change to color in all my images, the prints match exactly to the display just as they did under 6500K except my images look butt ugly but so do the prints. They didn't before I switched to 5000K.
    Wrap that one around your head. I give up.
     
  10. Tim, I made those photos in open shade; the newsprint will ride blue more because of the power of thalocyanine blue; it's a very strong blue dye that's in just about everything from blue jeans to chemical toilets. I think you're images look great, but out of preference alone, I ride with 5000K for everything.
     
  11. I have been very interested in arguments such as these lately due to my own quest for a properly color managed workflow… Martin Evening argues that you should set the gamma and white point to their defaults (which he mentions are typically very close to 2.2 and 6500k.) However my displays defaults are gamma 1.809, 5197°k and luminance of 195c/m^2) What do you recommend one does in my particular situation (where the accepted values are far from my display's defaults)? i.e. is it better to leave the display near it's defaults and potentially compromise the full range it may be capable of or set the gamma, luminance and WP at predetermined values - values that are WIDELY argued to be correct/incorrect/misinformation)
     
  12. Nathan, the whole point of calibration is to adhere to a standard for editing images so everyone is on the same page when they view your images on the web on other calibrated displays. 2.2 gamma and 6500K is a setting that optimizes the full gamut and dynamic range of a display.
    As long as you have a hardware calibration package you can force your display into this standard through the video card if you don't have a display with built in high bit LUT's which uses software to force it into this standard instead of through the video card.
    My iMac's native color temp is 6000K and I forced it into 6500K having i1Display software do it through the video card. I didn't loose any noticeable levels when I edit my images.
    I don't know anything about your display. I don't know how you arrived at the numbers you mention describing the native state of your display. Don't know if that's even the native state of your display or if you have menu buttons that say those are the numbers.
    Can you adjust the menu buttons on the display to put it closer to 2.2 gamma, 6500K and at least as low as 120 cd/m2?
     
  13. Hi Tim,
    I have a gateway hd2200 with contrast and brightness adjustments. The default values are what i've read with my Spyder3 Elite with the display set back to factory specs. I am able to adjust the luminosity as well as the gamma and color temp through the spyder software. There just seems to be an incredible amount of conflicting advice as to what is "correct." For example, the UPDIG guide states "Some argue for creating monitor profiles using native color temperature and native gamma, and let your eyes adjust to the difference between the monitor and the print or proof. Doing so will ensure you get the widest dynamic range the monitor can produce. It will also minimize artifacts, banding and posterization, which become more noticeable as you force a monitor (especially a standard, 8-bit monitor) farther from its native white point and gamma." They also state "gamma correction may vary from 1.0 to 3.0, or be based on L* gamma. The monitor’s luminance may vary from 80 cd/m² to 140 cd/m². Adjust these settings based on viewing conditions. If comparing the monitor with proofs in a viewing booth, adjust to the best match. The correct luminance also depends on ambient light conditions. High-end color work should take place in ambient light controlled for color temperature, flare and luminance. For work in bright office or studio environments, you might need a luminance of more than 140 cd/m2 to see shadow detail on your monitor. The purpose of monitor calibration and profiling is to create a situation where the image on your monitor closely matches the image as it will appear on a print, a proof, a press sheet – or, if your work is destined for the web, as viewed on the average un-calibrated PC or Mac monitor. Desired white points range from 5000K (yellow-red) to 6500K (bluer).

    They go on to say that "There is no single standard for white point, gamma and luminance, because there is no standard for what you are trying to match. If you are working in pre-press, you will want to match press proofs and press sheets. For this, you may find a white point of 5000K or 5500K will give you the best match of monitor to proof or press sheet viewed under a 5000K light. The appropriate luminance may be around 100cd/m². If you are preparing files for ink-jet or Lightjet printing, you may find that a white point of 6000K or 6500K will give you the closest match, although you should always view the prints under the color temperature of the lighting where they’ll be displayed. Once again, monitor luminance should match the appearance of the display prints in the viewing condition. Prepare image files for the web on a monitor calibrated and profiled to the sRGB standard gamma of 2.2 and white point of 6500K. This will be a compromise between the uncalibrated Mac gamma standard of 1.8 and the uncalibrated PC standard of 2.4."
    So it seems no one can agree on an optimum setting for everyone to adhere to?
     
  14. UPDIG guide states "Some argue for creating monitor profiles using native color temperature and native gamma, and let your eyes adjust to the difference between the monitor and the print or proof. Doing so will ensure you get the widest dynamic range the monitor can produce. It will also minimize artifacts, banding and posterization, which become more noticeable as you force a monitor (especially a standard, 8-bit monitor) farther from its native white point and gamma.​
    Correct (at least in terms of banding, I can’t say the bit about dynamic range is correct. Besides, the dynamic range of nearly all LCD’s is way too wide compared to any printer).
    The right value is the one that produces a match to your print, based on the print viewing conditions OR a match for others in the workflow in differing locations. There is no right, magic number other than maybe Native Gamma if the software supports it.
     
  15. Nathan, I think you're making this more difficult than it has to be. Matching luminance levels between your ambient/print viewing environment and your display is far more important than nailing color temp appearances.
    Below is a shot I made of my studio editing environment and the lights I view my prints under. I have the curtains open to show how bright daylight coming in to the room can affect the appearance of luminance on a display calibrated to a luminance under 120 cd/m2. You'll note overcast daylight has less luminance and shows what version of daylight 6500K really resembles.
    As you can see from the images, when your eyes adjust, 6500K isn't that blue looking compared to actual daylight and daylight balanced artificial light. This image sample also illustrates the many variations of color temp color cast and how a Kelvin number associated with it varies so matching your display to them exactly is pretty futile. A neutral looking display is far more important than matching to some Kelvin number.
    If your display is neutral looking when viewed at night with no lights on so as not to influence your eyes then go with that look and forget the Kelvin numbers. Your eyes, not a colormeter, are going to be assessing color on your display when editing.
    00UxqP-188707584.jpg
     

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