import matplotlib.pyplot as plt import matplotlib.image as mpimg import pyfits import numpy def Gaf(x): f = pyfits.open(x) i = f[0] d = i.data plt.imshow(d) plt.show(d) def Signal(x,x1,x2,y1,y2,xx1,xx2,yy1,yy2): f = pyfits.open(x) i = f[0] d = i.data u = d[x1:x2,y1:y2].sum()-(((x2-x1)*(y2-y1))/((xx2-xx1)*(yy2-yy1)))*(d[xx1:xx2,yy1:yy2].sum()) print u Signal("C:\Users\Luca\Desktop\Atlas_pleione_onesec.fit",100,200,100,200,100,200,100,200)