Re: Affinity Photo and colorsync issue, maybe
Re: Affinity Photo and colorsync issue, maybe
- Subject: Re: Affinity Photo and colorsync issue, maybe
- From: edward taffel <email@hidden>
- Date: Sat, 26 Mar 2016 15:23:04 -0400
> On Mar 26, 2016, at 3:39 AM, Graeme Gill <email@hidden> wrote:
>
> edward taffel wrote:
>
>> it seems that cmm code for performing transformations must be very similar across most
>> implementations;
>
> CMM != Profile creator.
yes, of course: i meant the algorithms applied by a configured fsm.
>>>> On Mar 25, 2016, at 11:14 AM, Ben Goren <email@hidden <mailto:email@hidden>> wrote:
>>>>
>>>>> ArgyllCMS is so far superior to anything and everything else out there
>>>>
>>>> to what do you attribute this?
>>>
>>> Graeme Gill, its author.
…
>>> Graeme instead has put insane amounts of time into investigating edge cases, figuring out why this-or-that is close but not perfect, and so on.
such enthusiasm engenders interest.
> Even in the execution of basic profile conversions, there is subtle
> room for differences. Is the implementation fixed point or floating point ?
> Is higher accuracy carried through each step of a transformation, or is
> it truncated at each step ? etc.
i gather then, you claim superior precision, & this may account for ben’s superior results; but, what of the ‘edge cases’ ben mentions? are these obviated by precision?
i have found that colorsync may fail to match a color it reported out-of-gamut, i.e. transforms the coordinates, but the transformed color remains out-of-gamut. when i first encountered this [four years ago], claudio wilmanns made me aware of ‘edge conditions’; i tried to discover heuristics to cope—back-burner that!
can you enlighten us as to the handling of ‘edge cases’?
regards,
edward
>
> Even CMM's sometimes have some unexpected quirks - BPC for instance,
> or slope limits applied to power curves, etc.
>
> Graeme Gill.
>
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