JP-2944: Limit major axis expansion for MIRI shower flagging (#123)

* Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update jump.py * Update CHANGES.rst * Update jump.py * Update jump.py * Update jump.py * Update CHANGES.rst Co-authored-by: Howard Bushouse <[email protected]>
spacetelescope · Oct 14, 2022 · dd7cb2c · dd7cb2c
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diff --git a/CHANGES.rst b/CHANGES.rst
@@ -1,6 +1,13 @@
 1.2.1 (unreleased)
 ==================
 
+Bug Fixes
+---------
+
+jump
+~~~~
+- Changes to limit the expansion of MIRI shower ellipses to be the same
+  number of pixels for both the major and minor axis. JP-2944 [#123]
 
 1.2.0 (2022-10-07)
 ==================
@@ -18,11 +25,11 @@ jump
 ~~~~
 
 - Changes to flag both NIR snowballs and MIRI showers
-for  JP-#2645. [#118]
+  for  JP-#2645. [#118]
 
 - Early in the step, the object arrays are converted from DN to electrons
-by multiplying by the gain. The values need to be reverted back to DN
-at the end of the step. [#116]
+  by multiplying by the gain. The values need to be reverted back to DN
+  at the end of the step. [#116]
 
 1.1.0 (2022-08-17)
 ==================

diff --git a/src/stcal/jump/jump.py b/src/stcal/jump/jump.py
@@ -407,11 +407,19 @@ def extend_ellipses(plane, ellipses, sat_flag, jump_flag, expansion=1.1):
     for ellipse in ellipses:
         ceny = ellipse[0][0]
         cenx = ellipse[0][1]
-        majaxis = ellipse[1][0] * expansion
-        minaxis = ellipse[1][1] * expansion
+        # Expand the ellipse by the expansion factor. The number of pixels added to both axes is
+        # the number of pixels added to the minor axis. This prevents very large flagged ellipses
+        # with high axis ratio ellipses. The major and minor axis are not always the same index.
+        # Therefore, we have to test to find which is actually the minor axis.
+        if ellipse[1][1] < ellipse[1][0]:
+            axis1 = ellipse[1][0] + (expansion - 1.0) * ellipse[1][1]
+            axis2 = ellipse[1][1] * expansion
+        else:
+            axis1 = ellipse[1][0] * expansion
+            axis2 = ellipse[1][1] + (expansion - 1.0) * ellipse[1][0]
         alpha = ellipse[2]
-        image = cv.ellipse(image, (round(ceny), round(cenx)), (round(majaxis / 2),
-                           round(minaxis / 2)), alpha, 0, 360, (0, 0, 4), -1)
+        image = cv.ellipse(image, (round(ceny), round(cenx)), (round(axis1 / 2),
+                           round(axis2 / 2)), alpha, 0, 360, (0, 0, 4), -1)
         jump_ellipse = image[:, :, 2]
         saty, satx = np.where(sat_pix == 2)
         jump_ellipse[saty, satx] = 0