From 15815fb54d162bb682834f106ca0d23221ca2cfc Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <vrabaud@google.com>
Date: Thu, 20 Jul 2023 17:54:42 +0200
Subject: [PATCH] Fix stereoRectify image boundaries.

This should hav ebeen fixed with https://github.com/opencv/opencv/issues/23304
---
 modules/calib3d/src/calibration.cpp           |  8 ++--
 .../calib3d/test/test_cameracalibration.cpp   | 48 +++++++++++++++++++
 2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/modules/calib3d/src/calibration.cpp b/modules/calib3d/src/calibration.cpp
index 9e8c252cee..002394b917 100644
--- a/modules/calib3d/src/calibration.cpp
+++ b/modules/calib3d/src/calibration.cpp
@@ -2699,11 +2699,11 @@ void cvStereoRectify( const CvMat* _cameraMatrix1, const CvMat* _cameraMatrix2,
     if( alpha >= 0 )
     {
         double s0 = std::max(std::max(std::max((double)cx1/(cx1_0 - inner1.x), (double)cy1/(cy1_0 - inner1.y)),
-                            (double)(newImgSize.width - cx1)/(inner1.x + inner1.width - cx1_0)),
-                        (double)(newImgSize.height - cy1)/(inner1.y + inner1.height - cy1_0));
+                            (double)(newImgSize.width - 1 - cx1)/(inner1.x + inner1.width - cx1_0)),
+                        (double)(newImgSize.height - 1 - cy1)/(inner1.y + inner1.height - cy1_0));
         s0 = std::max(std::max(std::max(std::max((double)cx2/(cx2_0 - inner2.x), (double)cy2/(cy2_0 - inner2.y)),
-                         (double)(newImgSize.width - cx2)/(inner2.x + inner2.width - cx2_0)),
-                     (double)(newImgSize.height - cy2)/(inner2.y + inner2.height - cy2_0)),
+                         (double)(newImgSize.width - 1 - cx2)/(inner2.x + inner2.width - cx2_0)),
+                     (double)(newImgSize.height - 1 - cy2)/(inner2.y + inner2.height - cy2_0)),
                  s0);
 
         double s1 = std::min(std::min(std::min((double)cx1/(cx1_0 - outer1.x), (double)cy1/(cy1_0 - outer1.y)),
diff --git a/modules/calib3d/test/test_cameracalibration.cpp b/modules/calib3d/test/test_cameracalibration.cpp
index d2ab906fee..f5e80bbd28 100644
--- a/modules/calib3d/test/test_cameracalibration.cpp
+++ b/modules/calib3d/test/test_cameracalibration.cpp
@@ -2150,6 +2150,54 @@ TEST(Calib3d_StereoCalibrate, regression_11131)
     EXPECT_GE(roi2.area(), 400*300) << roi2;
 }
 
+TEST(Calib3d_StereoCalibrate, regression_23305)
+{
+    const Matx33d M1(
+        850, 0, 640,
+        0, 850, 640,
+        0, 0, 1
+    );
+
+    const Matx34d P1_gold(
+        850, 0, 640, 0,
+        0, 850, 640, 0,
+        0, 0, 1, 0
+    );
+
+    const Matx33d M2(
+        850, 0, 640,
+        0, 850, 640,
+        0, 0, 1
+    );
+
+    const Matx34d P2_gold(
+        850, 0, 640, -2*850, // correcponds to T(-2., 0., 0.)
+        0, 850, 640, 0,
+        0, 0, 1, 0
+    );
+
+    const Matx<double, 5, 1> D1(0, 0, 0, 0, 0);
+    const Matx<double, 5, 1> D2(0, 0, 0, 0, 0);
+
+    const Matx33d R(
+        1., 0., 0.,
+        0., 1., 0.,
+        0., 0., 1.
+    );
+    const Matx31d T(-2., 0., 0.);
+
+    const Size imageSize(1280, 1280);
+
+    Mat R1, R2, P1, P2, Q;
+    Rect roi1, roi2;
+    stereoRectify(M1, D1, M2, D2, imageSize, R, T,
+                  R1, R2, P1, P2, Q,
+                  CALIB_ZERO_DISPARITY, 0, imageSize, &roi1, &roi2);
+
+    EXPECT_EQ(cv::norm(P1, P1_gold), 0.);
+    EXPECT_EQ(cv::norm(P2, P2_gold), 0.);
+}
+
 TEST(Calib3d_Triangulate, accuracy)
 {
     // the testcase from http://code.opencv.org/issues/4334