CHROMiX

standard(refernece) LAB values

Hi, for my degree in college of Multimedia, i must create 3 icc profiles (with canon IPF5000) for three different types of paper used. my refernece test chart was TC3.5 CMYK i1(A3). The values i got measuring the three differnt test charts were converted to Lab values. Now i need to calculate colorimetric differnece beetwen my results(lab values on papir. ex. kunstdruck 115g) and standard values, but i can’t find the standard LAb values for TC3.5 CMYK i1(A3). Did i miss something? Thx for helping

Actually, there are not any Lab values in the reference files which profiles are made from. There is not any “original standard” that these measurements would be compared to. Read the following in order to get a better understanding of this:
Color_Management_Myths_2

I like to think of the relationship between reference and measurement as that of language translation rather than mathematical computation. The reference file is in “device” language (in your case, CMYK) which does not know anything about “absolute” color definitions - while the measurement file is in Lab language - defining a specific color. That’s why the profile can take the specific color you’re trying to print (in Lab space) and translate it into a number that the printer understands (CMYK).

http://www.colorwiki.com/wiki/The_Color_of_Toast is a good article to read to get a better grasp on this concept.

Maybe you can compare your 3 measurements to each other, or to an average of the three? Or maybe you’re supposed to compare your measurements to a standard like Gracol or SWOP?

Hi and first of all, thanks for help! . When i first try to solve this problem (to get refernece Lab values), i taked the LAB values from photoshop for colors RGB and CMYK. This princip was wrong because i didn’t take in knowledge the charachterisitc of my papers. On the internet i found that the standard for ink jet is DIN ISO 12 647 (Am i right?).I found about this standard at this page summitmedia.com.ph/downloads … ab_iso.pdf
So if i’m right about that, i will compare my LAB values of my three papers to this standard. My problem here is that i don’t know in which group’s of paper described in this standard i will put my papers to get refernce LAb values fpr them. I used kunstdruck paper(which i guess is artistic paper, both side coated, and shiny, gm 115 and 350), and woodfree paper 80g( non coated). If you see the page i linked, u will see where is my problem. in group 1 i could put my kundstruck papers, but i dont know if the kundstruck is wood free. At the other way, i could put my wood free paper in group 4, because is not coated, and is white(ofc), but it’s woodfree. I hope that u get my problem.

P.S. im new in this field, so sorry about some possible stupid things i wrote. and i didn’t heared about stabdard u mentioned(Gracol, Swop), and im considering to put them in my paper, if im able to find a way to use them properly. And yes, i compared the LAB values of my papers to each other, but i must also compare them to refernce according to ISO 12 647.

Okay, according to your PDF you’re going for ISO 12647-2, and this paper gives you the Lab values for 5 different paper types. In my opinion you’d be pretty safe using group 1 for your tests. Most papers fall into that category.