Re: [Lcms-user] out-of-gamut condition

[Marti M. <ma...@li...>]

Hi Andrea,

> I know CIE defines Y value in range 0..100
> so why sometimes is used the range  0..1.0? In lcms the range 0..1.0 is 
> also used for other color standard? (e.g. CIE Lab?)

Yep, it should be in the documentation. 
I'm using 0..1.0 just because the ICC spec uses that convention. 

Lab is in the "normal" range of L: 0..100, a,b: -128..127

Regards,
Marti Maria
The little cms project
http://www.littlecms.com




----- Original Message ----- 
From: "Andrea Galligani" <da...@ti...>
To: <lcm...@li...>
Sent: Monday, December 20, 2004 10:39 AM
Subject: Re: [Lcms-user] out-of-gamut condition


> Hi Marti,
> thank you for aid, it was a range problem.
> 
> I'm new to lcms and color management so apologize my tedious questions.
> 
> I took a look to documentation and I cannot find info about color 
> ranges. I know CIE defines Y value in range 0..100
> so why sometimes is used the range  0..1.0? In lcms the range 0..1.0 is 
> also used for other color standard? (e.g. CIE Lab?)
> 
> Regards,
> Andrea
> 
> Marti Maria wrote:
> 
> >Hi,
> >
> >It works to me... you can try icctrans utility that does the same:
> >
> >First I try a blue tone that is outside SWOP gamut, then a gray 
> >that is inside. icctrans is marking out of gamut  as (255, 255,255)
> >
> >F:\lcms>icctrans -t1 -i*XYZ -o*sRGB -g -p USWebCoatedSWOP.icc
> >little cms ColorSpace conversion calculator - v1.8
> >
> >Enter values, 'q' to quit
> >X? 0.124
> >Y? 0.528
> >Z? 0.622
> >
> >R=255.00 G=255.00 B=255.00
> >
> >Enter values, 'q' to quit
> >X? 0.21
> >Y? 0.22
> >Z? 0.18
> >
> >R=129.09 G=129.81 B=128.27
> >
> >Enter values, 'q' to quit
> >X? q
> >Done.
> >
> >Maybe you are using XYZ values on 0..100 range? Try to normalize them
> >to 0..1.0, that is, divide XYZ values by 100. It should work. 
> >
> >Besides, there are many improvements on gamut cheking in 1.14, so
> >I would recommend to try the last version.
> >
> >Regards,
> >Marti Maria
> >The little cms project
> >http://www.littlecms.com
> >
> >
> >----- Original Message ----- 
> >From: "Andrea Galligani" <da...@ti...>
> >To: <lcm...@li...>
> >Sent: Friday, December 17, 2004 11:24 AM
> >Subject: [Lcms-user] out-of-gamut condition
> >
> >
> >  
> >
> >>Hi,
> >>
> >>I need to check the out-of-gamut condition of several XYZ points in a 
> >>generic profile.
> >>I tried the following code:
> >>
> >>    hInProfile  = cmsCreateXYZProfile();
> >>    hOutProfile = cmsCreate_sRGBProfile();
> >>    hProofProfile = cmsOpenProfileFromFile( m_ProfileName, "r");
> >> 
> >>    hColorTrans = cmsCreateProofingTransform( hInProfile, TYPE_XYZ_DBL,
> >>                                         hOutProfile, TYPE_RGB_8,
> >>                                         hProofProfile,
> >>                                         INTENT_PERCEPTUAL,
> >>                                         INTENT_ABSOLUTE_COLORIMETRIC,
> >>                                         cmsFLAGS_GAMUTCHECK | 
> >>cmsFLAGS_SOFTPROOFING );
> >>    cmsSetAlarmCodes( 0, 0, 0 );
> >>
> >>but any XYZ point translated using
> >>    cmsDoTransform( hColorTrans, XYZarray, RGBarray, nPoints );
> >>
> >>produces an out-of-gamut condition (a (0, 0, 0) RGB value)
> >>
> >>I tried several profiles, including the standard sRGB, obtaining the 
> >>same result.
> >>
> >>Probably I do something wrong but I don't know where.
> >>
> >>Can somebody help me?
> >>Thank you in advance.
> >>
> >>Andrea
> >>
> >>-------------------------------------------------------
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> >>    
> >>
> -- 
> 
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