Re: JND [was: Color Measurement]
Re: JND [was: Color Measurement]
- Subject: Re: JND [was: Color Measurement]
- From: Marco Ugolini <email@hidden>
- Date: Thu, 16 Jul 2009 13:50:19 -0400 (EDT)
Robin Myers wrote:
>However, in the example given by Klaus Karcher, the L*a*b* values
>differed by 5 units in the b* values, the other values were the same,
>and only dE 1976 correctly represented the dE as 5 units. For this and
>other reasons, dE 2000 and dE 1994 are not recommended for dEs greater
>than 5 units (it is not clear if this 5 unit threshold is in the dE
>1976 space or the others). dE 1976 is still recommended for expressing
>large dE values.
>
>The unevenness of dE values throughout the color space is not due to
>the dE 1976 equation but rather to the unevenness of L*a*b* space
>itself.
Hi Robin.
It's also true, though, that human vision has a limited ability to perceive differences in yellows, and DeltaE 2000 accounts for that. A difference of 5 units of b* between two yellows may result in a barely perceptible visual difference to the average human observer.
Marco
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