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Gday.

In my room I have a monitor that I feel is good for color accuracy. It's not the best but it's the best i've had. It's an LG 24MP76.

I like processing my photos, so I bought some LIFX light bulbs. With these ligthbulbs I can control the color temperature of my ambient light, in my room, while I am processing my photos.

What is a good colour temperature for evaluating my photos on the monitor?

Currently, in my workflow I turn off f.lux, and max out the brightness in the monitor. I don't own color calibration hardware for my computer - like Spyder or similar.

Thank you.

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    It is much more critical to be sure in that your screen either accurately conforms to sRGB or you have a good profile for it. Most monitors do not comply to sRGB well and the worst part of it is white point difference (most are warmish). I could not find the review of monitr ATM. – Euri Pinhollow Apr 25 '16 at 9:49
  • @EuriPinhollow Just for clarity, you mean "warmish" as in higher Kelvin color temperature, which means more blue, which is "colder" in the traditional sense in art, right? – mattdm Apr 25 '16 at 12:18
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    Huh. That is very contrary to my experience. Especially laptop screens, but televisions and others as well tend to be veey shifted towards blue. I've heard that this is because it looks crisp and bright in store showrooms, so there's "evolutionary pressure" for competing screens to default to bluer and bluer defaults. – mattdm Apr 25 '16 at 12:57
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    @mattdm: either way, difference between assumed white point and actual white point is more important than chromatic adaptation. – Euri Pinhollow Apr 25 '16 at 14:01
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    Why would you max out the brightness of your monitor? Most monitors are capable of 250-300 cd/m² yet the industry standard for LCD monitors is 120 cd/m² and for CRT monitors is 100 cd/m². – Michael C Apr 26 '16 at 7:23
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The industry standard for viewing color prints is 5500⁰K. I think that this fact is moot when viewing images on a monitor. Becasue the human eye/brain combination has a built-in white balance mechanism, the brain automatically adjusts the sensitivity of our vision system. This occurs all the time but you are likely unaware.

Try this test: Procure some deep colored filters (red, blue, green etc.). Candy wrappers or gift wrapping cellophane will work. Cover one eye with the filter and stare out the window at a sunlit vista or at a lamp in the room. Keep the filter on your eye for 2 to 4 minutes. Now remove the filter and look about, for a few seconds with one eye closed. Now switch eyes. You will see that the once filtered eye has drastically changed its color balance. This experiment will reveal the extent of this human automatic white balance. It makes you aware because each eye is controlled by the brain independently. Do try this experiment; it tells you a lot about human color vision.

Note: The photo industry and the lighting industry adopted the Kelvin temperature scale. This is the Celsius scale, however it starts at -273⁰C. The idea is, the Kelvin scale, starting at absolute zero (lowest possible temperature) has only positive values. Also, as all materials are heated, they glows first yellow-hot, then red-hot, then white-hot, then blue-white-hot. Potters, glass blowers and metal smelters judged the temperature of the material by its color. Early photo lamps were glowing tungsten, and the temperature of the glowing metal correlates to its color output. Films were formulated to operate under different color illuminates identified by their Kelvin temperature.

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    The industry standard for viewing prints is actually D55 which, in addition to being centered on 5500K, includes specifications for specific levels of other wavelengths present including UV. There are those who advocate using D65 for monitors, but only if the ambient light is also fairly full spectrum and centered on 6500K. In the CFL/LED environment, bulbs with a higher Kelvin center tend to be fuller spectrum as well. Almost all of them have output in the 2000-2800K range, but the 2700K bulbs put out very little above 3500-4000K. – Michael C Apr 26 '16 at 7:26
  • Gday. Yes, I know how the eye adapts. It's quite interesting and I have learnt to be conscious of it. This is especially important when taking pics jpeg-only in a yellow-light room - and having all your photos "seem great!" while in the room, only to look super yellow afterwards. :/ – Peter pete Apr 26 '16 at 12:08
  • Notes from a Kodak seminar: A reasonable room illuminate for print viewing - install 4 foot fluorescent lamps CW (cool white). For each tube, add one 60 watt household tungsten light bulb. My notes are dated 30 years ago but I think they remain valid. Anyway this was an inexpensive method to adjust room illuminate to about 5500K – Alan Marcus Apr 26 '16 at 15:46
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This began as a comment and grew enough to become a potential "answer."

Here's a bit of physiological trivia that might throw some light (!) on why ~5000K was chosen as a good "correllated colour temperature" standard for critical colour comparison. At that wavelength, human eye receptors in the retina are optimal for red, green, and blue radiation.

Viewing light intensity is the second critical factor when dealing with colour. The light must be bright enough for your visual apparatus to function optimally too. The goal is even diffuse illumination at 500 lux on the surface of a print image to be examined/compared. Not many are aware of this necessity and it often goes ignored. When this is set properly, fix the settings so they won't change. Eliminate any variable natural source of illumination. The goal is consistency and stability. When using fluorescent sources, strive for a CRI (colour rendering index) as high as possible with a minimum of 90%.

When you are working with colour on a monitor, the ambient light colour temperature and intensity can be a factor due also to an "adjacency effect" in non-neutral coloured environments.

TIP: Sitting in front of your monitor OFF in your workspace with the normal working lights ON, what do you see? If you see reflections of yourself and what's behind you, remember that this reflection is additive—and is added to your image when the monitor is on. This will affect your perception of your monitor's output NO MATTER HOW CAREFULLY YOU CALIBRATE IT. Adjust your room lighting so that reflections do not interfere with your onscreen image. Many who work with colour wear black to minimize unwanted colour contamination during evaluation.

There are several fixed "standard" points of colour temperature along the "white" Planc curve on the ICC Colour chart. D65 (daylight) is one. D50 was chosen as another one for reasons mentioned above.

Aside: Printing press operators are accustomed to having a higher ambient colour temperature for more easily seeing low contrast (yellow ink on white) subjects for image alignment. The actual colour management is done electronically in a reserved area of the plant set aside for colour evaluation.

Now, you are ready to turn on your monitor to set its brightness level. While it is warming up a minimum of 30 minutes to stabilize, create a file using something like Photoshop that is 100% Red, 100% Green, and 100% Blue. Display this "document" on your screen while viewing a blank white paper beside your monitor. Shield the monitor from the paper illumination and the paper illumination from the monitor. Adjust the monitor (not the file) to match the subject brightness at 500 lux.

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