Re: Color Checker Age
Re: Color Checker Age
- Subject: Re: Color Checker Age
- From: edmund ronald <email@hidden>
- Date: Tue, 05 Nov 2013 00:00:50 +0100
I think we have two questions here - one is related to camera
profiling quality and the other to colorcheckers, but the two issues
are entangled.
In my experience, if you are going to play around with profiling, you
need to measure your colorchecker. in order to get a decent reference
file.
I would expect to measure even an SG if real accuracy is desired.
Edmund
On Mon, Nov 4, 2013 at 11:37 PM, Iliah Borg <email@hidden> wrote:
>> I'm using a rather old color checker and RPP64 for profiling, and am
>> getting peak errors of deltaE 11, and average errors of over 4. Is it
>> possible this is related to the age of the target, and if so, how long
>> should one be kept before replacing?
>
> The limitation here is the matrix type profile. It is important to realize that the profile error is calculated from the same target, and is simple deltaE, and as such it mostly shows the method limitations, not the profile accuracy. In deltaE2000 metrics max error will be less, probably about 5-6. It is definitely useful to measure the ColorChecker, you may get more accurate results but the error most probably will be the same, may decrease by 2 deltaE (regular deltaE, not 2000). Max error of 11-12 is typical for matrix-based profiles from ColorChecker. To get better results one needs ColorCheckerSG and may try LUT-based profiles ignoring noise added by LUTs - if not much digging into shadows is performed the noise LUTs add is quite tolerable. That does not mean it is easy to shoot any target, including regular ColorChecker with the quality needed for accurate profiling. It is also very important to understand that spectrophotometers are not 100% accurate and may have errors reaching and exceeding 3deltaE, even if freshly re-calibrated at the factory. Also, you can easily have 3 to 6 deltaE variation across the sensor. Profiles need to be checked not only by deltaE, but by visual inspection of the results of their application.
>
>>
>> Thanks
>>
>> --
>> Marc Sitkin
>>
>> digitalmomentum, llc.
>> 1700 NW 15th Ave
>> Suite 360
>> Pompano Beach, FL 33069
>> 954-973-2670 phone
>> 888-880-5851
>>
>> web site:
>> www.digitalmomentum.com
>> marcsitkinphotography.com
>> wideandnarrow.tumblr.com
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>
> --
> Best regards,
> Iliah Borg
>
>
>
>
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