Color accuracy validation on an HP Indigo

[tomlar1977]

Hi!

I have an HP Indigo 5500, which is making me a bit nervous, I don't think it is calibrating it self correct (long story and a lot of prints!), so I was wondering how do I do a manual validation? I have ProfileMaker 5.10 and a i1 Pro as available tools. My first thought was to create a testjob with a lot of patches, as normal color calibrations are done, and measure these with my i1 Pro, but my problem with that solution is that all I can measure (most likely because I lack the knowlegde) is either LAB colors or density values. Density values would do the trick, I suppose, but as long as I don't know what a 15% black area should be in density, I'm lost...! I do have the density values for 100% of the CMYK colors, but how do I convert or calculate the other values - or is there a better / easier way to do this validation?

Kind regards,
Tommy

 

[DigitalJuan]

Hi there,
It doesn't come clear to me what exactly is your problem - the accuracy of the calibration or the consistency during print?
There are several "levels" of color accuracy that can be reached - it's a game with groups of substrates included in the list of calibration.
From our point of view we found that it is much more accurate to make "Long Color Calibration" and right after that make "Short Color Calibration". I know it sounds wierd but it works.
I don't think you can profile the machine better than the vendor. But for accuracy you must find your proper curve to work with. This is a tricky part. Many times I have to reach a Fogra 39 certified proof I just go and set the "CMYK Plus" Profile and it does the 99% of the work.
Hope this helps somehow...

 

[tomlar1977]

Hi!

It's the accuracy of the calibration I'm concerned about (since you know Indigo, I can tell you that I can do every calibration without any problems, but it fails on color accuracy validation, and if I run that five times in a row, without doing anything else, it gives me five different results...).
What I'm basically after, is a testsheet, which I would print every now and then, and measure it manually, kind of like what a normal pressman does with the strip that is on every offset printed sheet. I know what I want, "just" need to know how to measure it

PS: I have a testjob which prints a sheet I can measure in MeasureTool, for Fogra39_MW3, but that gives me a 5 page result, which makes no sense for me as a normal person - I just need to measure a 10% box, a 15% box etc., and then I will know if I'm satisfied with the results myself

Kind regards,
Tommy

 

[tsdomenichelli]

Hello Tommy,

Does you have any update on this?

 

[tomlar1977]

Actually, I have found a way

I have attached a PDF file with the formula to calculate density values, it's not rocket science, just type the formula in Excel and the measure from your densitometer, and voila - you have it!

/Tommy