[libcamera-devel] [PATCH] utils: raspberrypi: ctt: Improve the Macbeth Chart search reliability

[David Plowman]

Previously the code would brighten up images in case the Macbeth Chart
is slightly dark, and also zoom in on sections of it to look for
charts occupying less of the field of view. But it would not do both
together.

This change makes the search for smaller charts also repeat that
search for the brightened up images that it made earlier, thereby
increasing the chances of success for non-optimal tuning images.

There are also a couple of very small drive-by typo fixes.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 utils/raspberrypi/ctt/ctt_macbeth_locator.py | 69 ++++++++++++--------
 1 file changed, 40 insertions(+), 29 deletions(-)

diff --git a/utils/raspberrypi/ctt/ctt_macbeth_locator.py b/utils/raspberrypi/ctt/ctt_macbeth_locator.py
index 3e95df89..178aeed0 100644
--- a/utils/raspberrypi/ctt/ctt_macbeth_locator.py
+++ b/utils/raspberrypi/ctt/ctt_macbeth_locator.py
@@ -57,6 +57,10 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
     """
     cor, mac, coords, msg = get_macbeth_chart(img, ref_data)
 
+    # Keep a list that will include this and any brightened up versions of
+    # the image for reuse.
+    all_images = [img]
+
     """
     following bits of code tries to fix common problems with simple
     techniques.
@@ -71,6 +75,7 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
     if cor < 0.75:
         a = 2
         img_br = cv2.convertScaleAbs(img, alpha=a, beta=0)
+        all_images.append(img_br)
         cor_b, mac_b, coords_b, msg_b = get_macbeth_chart(img_br, ref_data)
         if cor_b > cor:
             cor, mac, coords, msg = cor_b, mac_b, coords_b, msg_b
@@ -81,6 +86,7 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
     if cor < 0.75:
         a = 4
         img_br = cv2.convertScaleAbs(img, alpha=a, beta=0)
+        all_images.append(img_br)
         cor_b, mac_b, coords_b, msg_b = get_macbeth_chart(img_br, ref_data)
         if cor_b > cor:
             cor, mac, coords, msg = cor_b, mac_b, coords_b, msg_b
@@ -128,23 +134,26 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
         h_inc = int(h/6)
         """
         for each subselection, look for a macbeth chart
+        loop over this and any brightened up images that we made to increase the
+        likelihood of success
         """
-        for i in range(3):
-            for j in range(3):
-                w_s, h_s = i*w_inc, j*h_inc
-                img_sel = img[w_s:w_s+w_sel, h_s:h_s+h_sel]
-                cor_ij, mac_ij, coords_ij, msg_ij = get_macbeth_chart(img_sel, ref_data)
-                """
-                if the correlation is better than the best then record the
-                scale and current subselection at which macbeth chart was
-                found. Also record the coordinates, macbeth chart and message.
-                """
-                if cor_ij > cor:
-                    cor = cor_ij
-                    mac, coords, msg = mac_ij, coords_ij, msg_ij
-                    ii, jj = i, j
-                    w_best, h_best = w_inc, h_inc
-                    d_best = 1
+        for img_br in all_images:
+            for i in range(3):
+                for j in range(3):
+                    w_s, h_s = i*w_inc, j*h_inc
+                    img_sel = img_br[w_s:w_s+w_sel, h_s:h_s+h_sel]
+                    cor_ij, mac_ij, coords_ij, msg_ij = get_macbeth_chart(img_sel, ref_data)
+                    """
+                    if the correlation is better than the best then record the
+                    scale and current subselection at which macbeth chart was
+                    found. Also record the coordinates, macbeth chart and message.
+                    """
+                    if cor_ij > cor:
+                        cor = cor_ij
+                        mac, coords, msg = mac_ij, coords_ij, msg_ij
+                        ii, jj = i, j
+                        w_best, h_best = w_inc, h_inc
+                        d_best = 1
 
     """
     scale 2
@@ -157,17 +166,19 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
         h_sel = int(h/2)
         w_inc = int(w/8)
         h_inc = int(h/8)
-        for i in range(5):
-            for j in range(5):
-                w_s, h_s = i*w_inc, j*h_inc
-                img_sel = img[w_s:w_s+w_sel, h_s:h_s+h_sel]
-                cor_ij, mac_ij, coords_ij, msg_ij = get_macbeth_chart(img_sel, ref_data)
-                if cor_ij > cor:
-                    cor = cor_ij
-                    mac, coords, msg = mac_ij, coords_ij, msg_ij
-                    ii, jj = i, j
-                    w_best, h_best = w_inc, h_inc
-                    d_best = 2
+        # Again, loop over any brightened up images as well
+        for img_br in all_images:
+            for i in range(5):
+                for j in range(5):
+                    w_s, h_s = i*w_inc, j*h_inc
+                    img_sel = img_br[w_s:w_s+w_sel, h_s:h_s+h_sel]
+                    cor_ij, mac_ij, coords_ij, msg_ij = get_macbeth_chart(img_sel, ref_data)
+                    if cor_ij > cor:
+                        cor = cor_ij
+                        mac, coords, msg = mac_ij, coords_ij, msg_ij
+                        ii, jj = i, j
+                        w_best, h_best = w_inc, h_inc
+                        d_best = 2
 
     """
     The following code checks for macbeth charts at even smaller scales. This
@@ -238,7 +249,7 @@ def find_macbeth(Cam, img, mac_config=(0, 0)):
     print error or success message
     """
     print(msg)
-    Cam.log += '\n' + msg
+    Cam.log += '\n' + str(msg)
     if msg == success_msg:
         coords_fit = coords
         Cam.log += '\nMacbeth chart vertices:\n'
@@ -606,7 +617,7 @@ def get_macbeth_chart(img, ref_data):
                     '\nNot enough squares found'
                     '\nPossible problems:\n'
                     '- Macbeth chart is occluded\n'
-                    '- Macbeth chart is too dark of bright\n'
+                    '- Macbeth chart is too dark or bright\n'
                 )
 
             ref_cents = np.array(ref_cents)
-- 
2.34.1