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I was given some LAB measurements of color samples. The LAB measurements came with a statement that the illuminant is D50, but no specification of what standard observer was assumed (it would be either 2 or 10 degrees). The measurements are intended for graphic arts, and I think for D50 2 degrees is more commonly used than 10 degrees, but can you confirm this for me?

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Adobe LAB mode1, ICC consortium1, 2 and printing industry use D50 white point as the standard. In fact all ICC profiles are defined in D50 and the observer is "CIE Standard 1931 colorimetric observer" or 2 degree observer.2

So yes i would say the 2 degree observer and D50 is more commonly used given that most users don't actually know what they have chosen and that is the default or in fact only one the can choose.

  1. Plaisted, P. 2011. The Reference White in Adobe Photoshop Lab Mode
  2. Stanndard Specification ISO 15076-1:2010 or you can use ICC.2:2016-7 if you have trouble getting hands on the ISO standard
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The standard observer in Graphic Arts (printing, proofing) is D50, observer angle 2°. However, you need to be careful here since now we have a relatively new upgrade to the standard where we now have to add the amount of OBA in the paper to the measurement - using the M1 setting of your spectrophotometer to evaluate the colour. Older spectral instruments used the M0 illuminant (basically lamp light). Refer to the ISO 12647-2-2013 standard (available at www.iso.org. So I suggest you find out if the person who made the measurement used M0, M1, M2 or M3. The 10° viewing angle is (I think) often used when measuring with D65, which is used in all other industries but graphics - because our business is actually that of copying = imitating the colour of a sample/original. Other industries are only interested in the actual colour of the original when exposed to daylight (D65).

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