Re: Re: Color depth - Wikipedia, the free

• To: mathgroup at smc.vnet.net
• Subject: [mg105289] Re: [mg105231] Re: [mg105150] Color depth - Wikipedia, the free
• From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
• Date: Wed, 25 Nov 2009 23:04:42 -0500 (EST)
• References: <200911221111.GAA10588@smc.vnet.net>

```Hi,

why do you quote just this sentence and not the one where I said that
it's not clear what exactly this means?
But to make it clear: on my system

img = With[{n = 16^2},
ArrayFlatten[
Partition[
Table[{x, y, z}, {z, 0, 1, 1/(n - 1)}, {y, 0, 1, 1/(n - 1)}, {x,
0, 1, 1/(n - 1)}], Sqrt[n]]]] // Image[#, "Real"] &;
Export["~/tmp/24bit.bmp", img, "ColorDepth" -> 24]

results in an image which really has 256^3 different colors and *no*, I
could not see the difference between adjacent pixels since my eyes are
too bad. But Gimp told me that every pixel is different and

img2 = Import["~/tmp/24bit.bmp"];
Union@Flatten[img2[[1]], 1] // Dimensions

{16777216, 3}

looks promising too.
I hope this was what Roger wanted to know.

Cheers
Patrick

On Wed, 2009-11-25 at 16:53 -0600, DrMajorBob wrote:
> > every pixel has different rgb-values. This means if you put n=16^2 you
> > would have 256x256x256 colors...
>
> No... it means you'd have RGBColor with 256x256x256 distinct parameter
> triplets. That doesn't prove they're all distinct, implemented COLORS.
>
> We could set n=1024^2 just as easily, but is there an implemented color
> model (in Mathematica) with the required depth?
>
> Bobby
>
> On Wed, 25 Nov 2009 01:31:41 -0600, Patrick Scheibe
> <pscheibe at trm.uni-leipzig.de> wrote:
>
> > Hi,
> >
> > assume the following graphic in Mathematica
> >
> > With[{n = 4^2},
> >   ArrayFlatten[
> >    Partition[
> >     Table[{x, y, z}, {z, 0, 1, 1/(n - 1)}, {y, 0, 1, 1/(n - 1)}, {x,
> >       0, 1, 1/(n - 1)}], Sqrt[n]]]] //
> >  ArrayPlot[#, ColorFunction -> RGBColor] &
> >
> > when you check the values for the colors in this image you'll see that
> > every pixel has different rgb-values. This means if you put n=16^2 you
> > would have 256x256x256 colors in the image which is exactly what
> > "millions of colors" is supposed to be.
> > Since the table creates rational expressions for the {r,g,b} colors you
> > could easily (with the restriction that an image of that size would take
> > too long to render in Mathematica) create more colors by setting higher
> > values to n.
> >
> > But what does this mean? Are there really that many visible colors on
> > your screen? What happens if you export the image?
> > This depends many things, e.g. on your os-settings.
> >
> > So if you really want to know more, you have to tell more about what you
> > try to achieve and which things are not working for you.
> >
> > Cheers
> > Patrick
> >
> >
> >
> >
> >
> > On Sun, 2009-11-22 at 06:11 -0500, Roger Bagula wrote:
> >> http://en.wikipedia.org/wiki/Color_depth
> >>
> >> Does anyone know how to access thousand and millions of
> >> colors in Mathematica?
> >>
> >> Respectfully, Roger L. Bagula
> >> 11759 Waterhill Road, Lakeside,Ca 92040-2905,tel: 619-5610814 :
> >> alternative email: roger.bagula at gmail.com
> >>
> >>
> >>
> >
> >
>
>

```

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