// Open a FITS file and retrieve the first plane of the image array
// as a TASImage object
void FITS_tutorial3()
{
printf("\n\n--------------------------------\n");
printf("WELCOME TO FITS tutorial #3 !!!!\n");
printf("--------------------------------\n");
printf("We're gonna open a FITS file that contains several image\n");
printf("extensions. The primary HDU contains no data.\n");
printf("Data copyright: NASA\n\n");
if (!gROOT->IsBatch()) {
//printf("Press ENTER to start..."); getchar();
}
// Open extensions 1 to 5 from file
//printf("Press ENTER to see a canvas with all images within the file:"); getchar();
TCanvas *c = new TCanvas("c1", "FITS tutorial #1", 800, 700);
c->Divide(2,3);
for (int i=1; i <= 5; i++) {
TFITSHDU *hdu = new TFITSHDU("sample3.fits", i);
if (hdu == 0) {
printf("ERROR: could not access the HDU\n"); return;
}
TASImage *im = hdu->ReadAsImage(0);
c->cd(i);
im->Draw();
delete hdu;
}
}
// Open a FITS file and retrieve the first plane of the image array
// as a TASImage object
void FITS_tutorial1()
{
printf("\n\n--------------------------------\n");
printf("WELCOME TO FITS tutorial #1 !!!!\n");
printf("--------------------------------\n");
printf("We're gonna open a FITS file that contains only the\n");
printf("primary HDU, consisting on an image.\n");
printf("The object you will see is a snapshot of the NGC7662 nebula,\n");
printf("which was taken by the author on November 2009 in Barcelona (CATALONIA).\n\n");
if (!gROOT->IsBatch()) {
//printf("Press ENTER to start..."); getchar();
}
// Open primary HDU from file
TFITSHDU *hdu = new TFITSHDU("sample1.fits");
if (hdu == 0) {
printf("ERROR: could not access the HDU\n"); return;
}
printf("File successfully open!\n");
// Dump the HDUs within the FITS file
// and also their metadata
//printf("Press ENTER to see summary of all data stored in the file:"); getchar();
hdu->Print("F+");
printf("....................................\n");
// Here we get the exposure time.
//printf("Press ENTER to retrieve the exposure time from the HDU metadata..."); getchar();
printf("Exposure time = %s\n", hdu->GetKeywordValue("EXPTIME").Data());
// Read the primary array as a matrix,
// selecting only layer 0.
// This function may be useful to
// do image processing.
printf("....................................\n");
printf("We can read the image as a matrix of values.\n");
printf("This feature is useful to do image processing, e.g:\n");
printf("histogram equalization, custom filtering, ...\n");
//printf("Press ENTER to continue..."); getchar();
TMatrixD *mat = hdu->ReadAsMatrix(0);
mat->Print();
delete mat;
// Read the primary array as an image,
// selecting only layer 0.
printf("....................................\n");
printf("Now the primary array will be read both as an image and as a histogram,\n");
printf("and they will be shown in a canvas.\n");
//printf("Press ENTER to continue..."); getchar();
TASImage *im = hdu->ReadAsImage(0);
// Read the primary array as a histogram.
// Depending on array dimensions, returned
// histogram will be 1D, 2D or 3D
TH1 *hist = hdu->ReadAsHistogram();
TCanvas *c = new TCanvas("c1", "FITS tutorial #1", 800, 300);
c->Divide(2,1);
c->cd(1);
im->Draw();
c->cd(2);
hist->Draw("COL");
// Clean up
delete hdu;
}