Re: [Lcms-user] LCMS python

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

Sorry, a third thing. You need to marshal the input & output colour data 
using a special array format, because the bindings don't do that 
automatically. You need to do something like this:

         RGB = [255,255,255]
         rgb_in = uint8Array(in_comps * n_pixels)
         Lab_out = doubleArray(out_comps * n_pixels)
         for i in range(in_comps * n_pixels):
             rgb_in[i] = RGB[i]
         cmsDoTransform(....)
         Lab_tuple = tuple(Lab_out[i] for i in range(out_comps * n_pixels))

The test_05_transform_rgb_Lab test gives an example of what you should 
be doing. Sorry, that's the way it is until effort is put into doing 
automatic marshalling to/from Python lists.

John

On 27/03/2018 15:22, John Jefferies wrote:
>
> Hi,
> The first thing, cmsCIExyY() shouldn't be used as the white point of 
> the Lab profile. It is initialised to (0, 0, 0) which obviously isn't 
> right. You probably want cmsD50_xyY() instead.
>
> The second thing. The format of the RGB data is TYPE_RGB_DBL. That 
> doesn't match the [255, 255, 255] that's used. Use TYPE_RGB_8 instead.
>
> I haven't tested the result of applying these, but it should get you 
> further.
>
> John
>
> On 27/03/2018 10:12, Gonzalez Cano, Jordi wrote:
>>
>> I would like to use the LCMS with python, but when I want to call the 
>> function cmsDoTransform the following error appears: /TypeError: in 
>> method 'cmsDoTransform', argument 2 of type 'void const *'/
>>
>> What I am sending to the cmsDoTransform si the following:
>>
>> /array = [255,255,255]/
>>
>> /labColor = lcmsF.transformToLab(array,profileInURL,"RGB","perceptual")/
>>
>> //
>>
>> /--------------- /
>>
>> //
>>
>> /def transformToLab(inputColor, profileInURL, formatIn, intent, BPC = 
>> True):/
>>
>> /    LabColor = []/
>>
>> //
>>
>> /    labProfile = lcms.cmsCreateLab4Profile(lcms.cmsCIExyY())/
>>
>> /    inputProfile = lcms.cmsOpenProfileFromFile(profileInURL, "r")/
>>
>> //
>>
>> /    if(formatIn == "RGB"):/
>>
>> /        inType = lcms.TYPE_RGB_DBL/
>>
>> /    elif(formatIn == "CMYK"):/
>>
>> /        inType = lcms.TYPE_CMYK_DBL/
>>
>> //
>>
>> /    if(intent == "perceptual"):/
>>
>> /        m_intent = lcms.INTENT_PERCEPTUAL/
>>
>> //
>>
>> /    if(BPC):/
>>
>> /        m_BPC = lcms.cmsFLAGS_BLACKPOINTCOMPENSATION/
>>
>> /    else:/
>>
>> /        m_BPC = 0/
>>
>> /    transform = lcms.cmsCreateTransform(inputProfile, inType, 
>> labProfile, lcms.TYPE_Lab_DBL, m_intent, m_BPC)/
>>
>> //
>>
>> */    lcms.cmsDoTransform(transform,inputColor, LabColor, DIM_OUT)/*
>>
>> /    return LabColor/
>>
>> //
>>
>> How I am supposed to do it?
>>
>> Thanks,
>>
>> Jordi G.C.
>>
>>
>>
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