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
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