Re: Photoshop Lab values
Re: Photoshop Lab values
- Subject: Re: Photoshop Lab values
- From: Thomas Richard <email@hidden>
- Date: Mon, 9 Jul 2007 15:17:15 +0200
Hello,
take a look at a gamut visualization of ProPhoto RGB and you will see, that's right......
http://www.richard-ebv.de/images/HDS/Prophoto_darkblue.jpg
in theory ;-)
MfG
Thomas
>Hello. I have encountered a strange result that I don't understand.
>
>1) Create an RGB document in Photoshop in ProPhoto RGB color space.
>2) Fill some blocks with solid colors where R=G=0
>and B = [0, 17, 34, 51, ..., 255]
>3) Read Lab values with the color picker (single pixel)
>
>When I do this I get the following result:
>
>
> R G B L a b
>
> 0 0 0 0 0 0
> 0 0 17 0 0 -12
> 0 0 34 0 3 -32
> 0 0 51 0 6 -49
> 0 0 68 0 11 -63
> 0 0 85 0 17 -76
> 0 0 102 0 24 -88
> 0 0 119 0 31 -99
> 0 0 136 0 40 -110
> 0 0 153 0 48 -120
> 0 0 170 0 55 -128
> 0 0 187 0 63 -128
> 0 0 204 0 70 -128
> 0 0 221 0 76 -128
> 0 0 238 0 83 -128
> 0 0 255 0 89 -128
>
>What confuses me is that L* has a value of zero for all color patches.
>Shouldn't L* increase as B increases? It doesn't seem logical that an RGB of
>0, 0, 255 would have an L* of zero.
>
>What am I missing? Any thoughts?
>
>--
>Ken Fleisher
>
>Photographer
>Imaging & Visual Services
>National Gallery of Art
>Washington, D.C.
>
>Phone: (202) 712-7471
>email@hidden
>
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