SinoNormalization: fix coeff subtraction

nabu/preproc/sinogram.py

@@ -228,7 +228,7 @@ class SinoNormalization(SinoProcessing):
             ff0 = sino[i, :].sum()
             ff1 = (x * sino[i, :]).sum()
             ff2 = (f2*sino[i, :]).sum()
-            output[i, :] = sino[i, :] - ff0/sum0 + ff1*x/sum1 + ff2*f2/sum2
+            output[i, :] = sino[i, :] - (ff0/sum0 + ff1*x/sum1 + ff2*f2/sum2)
         return output