Re: ISO 12647-7
Re: ISO 12647-7
- Subject: Re: ISO 12647-7
- From: "Fleisher, Ken" <email@hidden>
- Date: Mon, 21 May 2007 13:41:43 -0400
- Thread-topic: ISO 12647-7
I replied a little to quickly.
Delta H is
dH =sqrt(dE^2 + dL^2 + dC^2)
Sorry about the poor plain text notation. For the values you quoted:
Delta E* = 0.14
Delta L* = 0.00
Delta C* = 0.14
Delta H = 0.20
Ken
On 5/21/07 12:55 PM, "Lee Badham" <email@hidden> wrote:
>> I agree that this is the way of calculating H normally, but how
>> could this work when measuring grey scales?
>> For instance,
>> Target Lab 50 0 0.1
>> Measured 50 0 -0.1
>>
>> This gives a H of 180 even though the 2 colours are very close
>>
>> Using the ab E method it gives a E of 0.28. I think this is the
>> method used within ISO 12647-7.
--
Ken Fleisher
Photographer
Imaging & Visual Services
National Gallery of Art
Washington, D.C.
Phone: (202) 712-7471
email@hidden
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