We are working on an interface to an image processing library. We could in that case create and image from the 2D hist and manipulate and draw directly the image, which is very fast. This image library allows the drawing of images in pads, to resize the pads and scale or tile the image, to print the images in the pads in PS or to save them to png, tiff, xpm, gif, etc. Of course you can also read these image formats, flip, rotate, merge images, grab any pad and save as any of the supported image formats, etc. Cheers, Fons. "Jacek M. Holeczek" wrote: > > Hi, > My colleague has met the problem that the performance of event display is > very low. Up to now a two dimensional histogram (TH2S, with channels > and samples as histogram bins and the signal amplitude, for a given > channel and sample, as a weight for the histogram entry) is used for the > event display. The problem is that in case of a large amount of channels > and samples (and this is the usual case) this method is very slow, and one > as to wait several minutes to have the histogram plotted (almost > independently from the machine, single and double PIII up to 750 MHz and > ATHLON 1.2 GHz give the same result). > We are looking for a way to improve it (significantly). > We think that, most probably, the best thing to do is to create a pixmap > or bitmap image, and plot it directly . There are methods like > "CreatePictureFromData", "CreatePixmap" and "CreateBitmap"in the > TGX11/TVirtualX (with the implementation in GX11Gui.cxx). > Do you have any hints on how to integrate this approach with ROOT ? > Or maybe you have any other suggestions ? > Thanks in advance, > Best regards, > Jacek. -- Org: CERN, European Laboratory for Particle Physics. Mail: 1211 Geneve 23, Switzerland E-Mail: Fons.Rademakers@cern.ch Phone: +41 22 7679248 WWW: http://root.cern.ch/~rdm/ Fax: +41 22 7679480
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