Re: [Lcms-user] Device space float ranges

[John J. <j.j...@nt...>]

Many thanks Marti,

John

On 04/05/2023 15:46, mar...@li... wrote:
> Hi,
>
> Problem is if I change this 100 scaling, I break photoshop notation, and many people is using that.
>
> A neat solution would be writing a formatter plug-in to replace double encoding to the scale you need.  You could copy & paste the formatters code you want to change from cmspack.c and modify it.
>
> You probably not need all the variants, so you could simplify the code and get some throughput boost.
> See some examples on plug-ins manual, "Formatters plug-in"
>
> Regards
> Marti Maria
> The LittleCMS Project
> https://www.littlecms.com
>
>
>
>> -----Original Message-----
>> From: John Jefferies via Lcms-user <lcm...@li...>
>> Sent: Thursday, May 4, 2023 2:13 PM
>> To: lcm...@li...
>> Subject: [Lcms-user] Device space float ranges
>>
>> Hello Marti,
>> I have a system where all colour spaces are device spaces (PT_GRAY, PT_RGB,
>> PT_CMYK, PT_MCH*), and all colour values are floats in the range of 0-1. I
>> therefore need a formatter to handle this, so I use this
>> formatter:
>>       cmsFormatterForColorspaceOfProfile(hProfile, sizeof(float), TRUE)
>>
>> It appears that lcms assumes that the client's float colour values are in the
>> range 0-100 if colour space is an IsInkSpace(). The problem then becomes
>> how to marshal my float values into and out of lcms. It appears that in client
>> code, I have to ensure the values are *100 or /100 as appropriate if the colour
>> space I have is an ink space.
>>
>> For my purposes, that's a bit daft. Firstly, IsInkSpace() isn't an exported
>> function so the client code has to duplicate the function itself. Secondly, it's
>> rather inefficient. Thirdly, the client code is uglier than it needs to be. Finally,
>> the assumed range of 0-100 isn't documented anywhere that I could find;
>> apologies if it is somewhere blindingly obvious.
>>
>> Is there any other way to use float values in the range 0-1?
>>
>> Regards + many thanks
>> John
>>
>>
>>
>> _______________________________________________
>> Lcms-user mailing list
>> Lcm...@li...
>> https://lists.sourceforge.net/lists/listinfo/lcms-user