Add _convert_halftomo_right

nabu/preproc/sinogram.py

@@ -171,7 +171,11 @@ def convert_halftomo(sino, rotation_axis_position):
     """
     assert sino.ndim == 2
     assert (sino.shape[0] % 2) == 0
+
     na, nx = sino.shape
+    if rotation_axis_position >= nx:
+        return _convert_halftomo_right(sino, rotation_axis_position)
+
     na2 = na // 2
     r = rotation_axis_position
     d = nx - r
@@ -189,6 +193,32 @@ def convert_halftomo(sino, rotation_axis_position):
     return res
 
 
+def _convert_halftomo_right(sino, rotation_axis_position):
+    """
+    Converts a sinogram into a sinogram with extended FOV with the "half tomography"
+    setting, with a CoR outside the image support.
+    """
+    assert sino.ndim == 2
+    assert (sino.shape[0] % 2) == 0
+    assert rotation_axis_position > sino.shape[1]
+    na, nx = sino.shape
+    na2 = na // 2
+    r = rotation_axis_position
+    d = r - nx
+    res = np.zeros((na2, 2 * r), dtype="f")
+
+    sino1 = sino[:na2, :]
+    sino2 = sino[na2:, ::-1]
+
+    w = np.linspace(0, 1, d, endpoint=True) # has to be adapted when the sample actually goes beyond this point
+    res[:, :nx] = sino1[:, :]
+    res[:, nx:nx+d] = sino1[:, -d:][:, ::-1] * (1 - w)
+    res[:, nx+d:nx+2*d] = sino2[:, :d][:, ::-1] * w
+    res[:, nx+2*d:] = sino2[:, :]
+
+    return res
+
+
 
 class SinoNormalization(SinoProcessing):
     """