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
This archive was generated by hypermail 2b29 : Sun Jan 02 2005 - 05:50:06 MET