# [argyllcms] Re: gamut conversion through the LUT ?!

• From: lee scratchy <leescratchy@xxxxxxxxxxx>
• To: <argyllcms@xxxxxxxxxxxxx>
• Date: Mon, 21 Jul 2008 21:25:44 +0000
```well yeah OK, I agree.

but the matlab computing is already done in the XLS spreadsheet ?!

what the Pixel Shader script does is a simple 3D matrix from what I understand :

sampler s0 : register(s0);float4 p0 : register(c0);
static float4x4 r2r
={0.99203472178032,-0.0422667239975349,0.0119267767888042,0,-0.0202728239852174,1.06051120942555,-0.0237148719178954,0,-0.00806166614011493,0.00483854619749899,0.979661484053003,0,0,
0, 0, 0};
float4 main(float2 tex : TEXCOORD0) : COLOR{    float4 c0 = tex2D(s0, tex);
c0 = pow(c0, 1/0.45);    c0 = mul(r2r, c0);    c0 = saturate(c0);    c0 =
pow(c0, 0.45);
return c0;}

so are you saying that this can't be done through the LUT ?

maybe with an ICC then ? but I read that LUT's are far more accurate than ICC's
?!
Thanks,

-Maxime
> Date: Mon, 21 Jul 2008 23:06:11 +0200> From: nospam456@xxxxxx> To:
> argyllcms@xxxxxxxxxxxxx> Subject: [argyllcms] Re: gamut conversion through
> the LUT ?!> > lee scratchy wrote:> > Ideally(and that's what a friend of mine
> is trying to do), the idea would be to output 16bit LUT data from the XLS
> spreadsheet(considering the matlab coeffs that it contains are very
> effective) then put them into the graphic card's LUT with dispwin.exe ?!> > >
> > Maxime,> > I'm afraid there is a misunderstanding. The VCGT LUTs which can
> be> loaded into the graphics card with "dispwin" are just one-dimensional>
> LUTs. Such LUTs do not allow arbitrary color transformation, but only> VERY
> LIMITED ones (like e.g. adjusting the gamma of the RGB channnels).> For the
> kind of color transformation you desire, you would need a> three-dimensional
> LUT. I'm not aware of graphics cards which support> that (except in
> conjunction with a pixel shader program), but I also> don't want to rule out
> that such graphics cards might exist.> > Regards,> Gerhard> >
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