Hi Seng,
A gray scale palette is the easiest to create. It is enough to define
your colors in a loop like:
dcol = 1/ncol;
gray = 0;
for (int j = 0; j < ncol; j++) {
...... Define color with RGB equal to : gray, gray, gray .......
gray += dcol;
}
Olivier
On Tue, 2 Mar 2004, Woon-Seng Choong wrote:
> Thanks Olivier. But how do I create a grayscale using
> CreateGradientColorTable instead of the DeepSea palette. What do I set
> for Red, Green, Blue, and Stops?
>
> Seng
>
>
> On Mar 2, 2004, at 12:24 AM, Olivier Couet wrote:
>
> >
> >
> > You can define more than 50 color. See the help of SetPalette in
> > TStyle:
> >
> > void TStyle::SetPalette(Int_t ncolors, Int_t *colors)
> > {
> > // The color palette is used by the histogram classes
> > // (see TH1::Draw options).
> > // For example TH1::Draw("col") draws a 2-D histogram with cells
> > // represented by a box filled with a color CI function of the cell
> > content.
> > // if the cell content is N, the color CI used will be the color number
> > // in colors[N],etc. If the maximum cell content is > ncolors, all
> > // cell contents are scaled to ncolors.
> > //
> > // if ncolors <= 0 a default palette (see below) of 50 colors is
> > defined.
> > // the colors defined in this palette are OK for coloring pads,
> > labels
> > //
> > // if ncolors == 1 && colors == 0, then
> > // a Pretty Palette with a Spectrum Violet->Red is created.
> > // It is recommended to use this Pretty palette when drawing legos,
> > // surfaces or contours.
> > //
> > // if ncolors > 50 and colors=0, the DeepSea palette is used.
> > // (see TStyle::CreateGradientColorTable for more details)
> > //
> > // if ncolors > 0 and colors = 0, the default palette is used
> > // with a maximum of ncolors.
> > //
> > // The default palette defines:
> > // index 0->9 : grey colors from light to dark grey
> > // index 10->19 : "brown" colors
> > // index 20->29 : "blueish" colors
> > // index 30->39 : "redish" colors
> > // index 40->49 : basic colors
> > //
> > // The color numbers specified in the palette can be viewed by
> > selecting
> > // the item "colors" in the "VIEW" menu of the canvas toolbar.
> > // The color parameters can be changed via TColor::SetRGB.
> >
> > This function is accessed via:
> >
> > gStyle->SetPalette();
> >
> > Cheers, O.Couet
> >
> > On Mon, 1 Mar 2004, Woon-Seng Choong wrote:
> >
> >> I have question concerning the color palette and the number of
> >> colors
> >> that one can defined in ROOT. I am interested in using ROOT to view a
> >> 2D image in grayscale (black and white) using the 2D histogram. I
> >> need
> >> a grayscale of at least 8 bits. As far as I can understand it, ROOT
> >> has a maximum of 50 colors. Is there a way to get more colors, in
> >> particular in grayscale? If not, is this a feature that would be added
> >> in the future?
> >>
> >> Seng
> >>
> >>
> >
> > --
> > Org: CERN - European Laboratory for Particle Physics.
> > Mail: 1211 Geneve 23 - Switzerland Mailbox:
> > J25910
> > E-Mail: Olivier.Couet@cern.ch Phone: +41
> > 22 7676522
> > WWW: http://cern.ch/Olivier.Couet/ Fax: +41
> > 22 7677155
> >
>
>
--
Org: CERN - European Laboratory for Particle Physics.
Mail: 1211 Geneve 23 - Switzerland Mailbox: J25910
E-Mail: Olivier.Couet@cern.ch Phone: +41 22 7676522
WWW: http://cern.ch/Olivier.Couet/ Fax: +41 22 7677155
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