Logo ROOT   6.21/01
Reference Guide
image2hist.C File Reference

Detailed Description

View in nbviewer Open in SWAN Create a 2-D histogram from an image.

pict1_image2hist.C.png
void image2hist()
{
TASImage image("$ROOTSYS/tutorials/image/rose512.jpg");
UInt_t yPixels = image.GetHeight();
UInt_t xPixels = image.GetWidth();
UInt_t *argb = image.GetArgbArray();
TH2D* h = new TH2D("h","Rose histogram",xPixels,-1,1,yPixels,-1,1);
for (int row=0; row<xPixels; ++row) {
for (int col=0; col<yPixels; ++col) {
int index = col*xPixels+row;
float grey = float(argb[index]&0xff)/256;
h->SetBinContent(row+1,yPixels-col,grey);
}
}
h->Draw("colz");
}
Author
Olivier Couet

Definition in file image2hist.C.