[argyllcms] Re: Whitepoint difference Argyll vs ProfileMaker and ProofMaster
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 21 Apr 2007 00:15:37 +0200
marcel nita wrote:
> Hello all,
>
> Made a profile for Epson 4800 ( ContractProof Paper ), first with
> Argyll and then with ProfileMaker, but using the same measurement
> files.
>
> There is a small difference between the whitepoint computed by Argyll
> and the one computed by ProfileMaker ( bigger in the Z component
> ~0.75 for Argyll, ~0.78 others ). Also, I measured the substrate with
> ProofMaster and computing the XYZ gave a very close value to the one
> of ProfileMaker.
>
> Did a little debugging and the difference seems to come from
> sp2cie_sconvert.
Did you specify the "-o" option? If I remember correctly, versions <=
0.60 use the J&V 1978_2 observer by default, and not the 1931_2. Use
"profile ... -o 1931_2 ..." to create standard compliant profiles. In
0.70 the default has changed and is now 1931_2.
Regards,
Gerhard
> The Lab computed here from spectral is different than
> what the other two apps get.
>
> Actually, the difference is better observed when doing a chromatic
> adaptation ( Bradford ) from ISO Coated to the printer profile. The
> substrate simulation when using the Argyll profile gets way off,
> shifted a lot towards magenta.
>
> When using ProfileMaker, the substrate gets a yellowish hue, which is
> correct.
>
> The difference between the two is better observed when doing an
> UgraFogra certification.
>
> I used Argyll v0.60 when testing.
>
> Can anyone say why this difference?
> I can't really attach anything now ( I'm off work ), but I'd be happy
> to attach the certify reports and/or the generated profiles on monday.
>
> Regards.
>
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