Human visual perception vs instrumental measurements [was: G7 press calibration, best press conditions or average?]
Human visual perception vs instrumental measurements [was: G7 press calibration, best press conditions or average?]
- Subject: Human visual perception vs instrumental measurements [was: G7 press calibration, best press conditions or average?]
- From: Marco Ugolini <email@hidden>
- Date: Fri, 07 Nov 2008 01:16:45 -0800
- Thread-topic: Human visual perception vs instrumental measurements [was: G7 press calibration, best press conditions or average?]
In a message dated 11/7/08 12:45 AM, Graeme Gill wrote:
> Paul Foerts wrote:
>
>> The eyeballs are used for comparing color and more.
>> Human vision is the most important element in the evaluation of the printing
>> process.
>
> I have always found human vision to be the most unreliable of
> ways of evaluating color in many situations, a characteristic
> common to all the human senses. [...] While human senses can be
> very good at comparative judgement, at times exceeding the sensitivity
> of instruments in this task, they are still subject to the bias of
> expectations, something that can only be guarded against by using elaborate
> procedures such as double blind testing. So the reality is that eyeballs and
> instruments need to work together in achieving good color reproduction,
> checking each other, used where they have strength, and compensating for each
> others weaknesses.
>
> For creating a repeatable and tight tolerance process though, I certainly
> wouldn't rely on eyeballs - they are subject to the frailties of their
> owners, and simply aren't consistent enough to be relied on as a reference.
I heartily agree with Graeme's points. They're both well-known in color
theory and easily proven in visual perception experiments.
To review a few persuasive examples of the limitations in human visual
perception, see:
<http://www.purveslab.net/seeforyourself>
<http://www.planetperplex.com/en/color_illusions.html>
Marco Ugolini
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