Getting the most accurate color in scans of old documents, photographs, etc.

Started Aug 10, 2022 | Questions thread
Overrank
Overrank Senior Member • Posts: 6,247
Re: Getting the most accurate color in scans of old documents, photographs, etc.
1

At the risk of sounding like a stuck record I’ll refer you again to

https://www.digitizationguidelines.gov/guidelines/FADGI%20Federal%20%20Agencies%20Digital%20Guidelines%20Initiative-2016%20Final_rev1.pdf

In particular Page 11 which covers some of your points:

There is no perfect imaging system or perfect method of colour evaluation. Colour accuracy is measured by DICE or a colour checker by computing the colour difference (ΔE2000) between the imaging results of the standard target patches and their pre-measured colour values. By imaging the DICE target and evaluating it through the DICE software, variances from known values can be determined, which is a good indicator of how accurate the system is recording colour. DICE measures the mean average deviation of all colour patches measured. Refer to ISO 13658:2000 for additional documentation on colour accuracy measurement.

In conventional photography I would use something like a Xrite ColorChecker passport ( https://www.xrite.com/categories/calibration-profiling/colorchecker-classic-family/colorchecker-passport-photo-2 ) and the associated software to correct for differences between the real world scene and my image of it, but Im not sure if that particular equipment is suitable for use in a scanner.

( so in short, you’re on the right track and it can all be automated so it’s not dependent on your opinion of the correct colour, but objective measurements )

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