Re: [Lcms-user] Question using planar configuration

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

Hi,

Yes, lcms does support planar data. The only condition is the output buffer
has to have space enough to hold all planes CONTIGUOUS.

So, your example would work if you use a big array

char chOutput[3+3+3+3];

Then, after cmsDoTransform, you have the array filled with

CCCMMMYYYKKK.

The format specifier is TYPE_CMYK_8_PLANAR.

Besides... do you have tried your code? it seems it should work
untouched. Just change the definition of output buffer and
then cmsDoTransform(hTransform, chInput, chOutput, 3);


Hope this helps,
Martí Maria
The little cms project
http://www.littlecms.com
ma...@li...


----- Original Message -----
From: "Ilja Fiers" <i....@ea...>
To: <lcm...@li...>
Sent: Wednesday, February 26, 2003 2:05 PM
Subject: [Lcms-user] Question using planar configuration


> Hello Marti & all lcms users,
>
> First of all, thanks for a great product, it is very well written and
> usefull! I have got a question about using the lcms engine in planar
> configuration. What i would like to do is offer the engine RGB data, and get
> a planar result back. But maybe i misinterpreted the word planar. A code
> example would be easyest i think.. Would the following be possible:
>
> //==========================================================================
> ================================
>
> // RGB value on input is 3 pixels,  rgb 20,30,40, rgb 50, 60,70, rgb 200,
> 210, 200
> // so, data format is RGBRGBRGB in one chunk of data
>
> unsigned char chInput[9] = {20,100,40,  50,70,60,  200,0,220};
>
> // output format is a separate array for c, m, y and k..., all of them three
> bytes in this case
>
> char chOutputC[3];
> char chOutputM[3];
> char chOutputY[3];
> char chOutputK[3];
>
> // rest of the abbreviated code
>
> hInProfile  = cmsOpenProfileFromFile("in.icc", "r");
> hOutProfile = cmsOpenProfileFromFile("out.icc", "r");
> hTransform = cmsCreateTransform(hInProfile, TYPE_RGB_8, hOutProfile,
> TYPE_CMYK_8_PLANAR, INTENT_PERCEPTUAL, 0);
>
> // do the transformation in one step...
> cmsDoTransform(hTransform, chInput, ?????, 3); // transform 3 pixels...
>
> //==========================================================================
> ================================
>
> Of course, this would be possible by converting the data to CMYKCMYKCMYK
> format using lcms, and then copying it myself to the separate planes.
> However, i think this would give me a speed penalty (does it?) since the
> engine might be optimised to do such a conversion directly.
> So, my question is: how do i offer the output data to the engine, if this is
> at all possible, and what output type do i request from cmsCreateTransform??
>
> Thanks for any suggestions..
>
> Ilja Fiers
>
>
>
>
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