v2.0, better quality, less perspective deformation (#1)

Reviewed-on: #1

gopro_8:7/unfish_gopro_8:7.py

@@ -0,0 +1,108 @@
+# Fisheye removal for GoPro 11+, 8:7 ratio, without hypersmooth
+# Copyright (C) 2025 Roz K <roz@rozk.net>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import math
+
+print("\n--- physical sensor ---\n")
+
+# https://www.sony-semicon.com/files/62/pdf/p-13_IMX677-AAPH5-J_Flyer.pdf
+
+sensor_pixel_size = 1.12 * 0.001 # mm
+
+# https://community.gopro.com/s/article/HERO11-Black-Video-Settings-And-Resolutions
+
+gopro_array_horizontal = 5312 # p
+gopro_array_vertical   = 4648 # p
+
+gopro_texture_horizontal = 3840 # p
+gopro_texture_vertical   = 3360 # p
+
+gopro_size_horizontal = gopro_array_horizontal * sensor_pixel_size
+gopro_size_vertical   = gopro_array_vertical   * sensor_pixel_size
+gopro_size_diagonal   = math.hypot(gopro_size_horizontal, gopro_size_vertical)
+
+print("gopro  size : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
+    gopro_size_horizontal,
+    gopro_size_vertical,
+    gopro_size_diagonal))
+
+# https://thinglabs.io/gopro-focal-length-guide
+
+gopro_focal_length = 2.92
+
+gopro_radius_horizontal = gopro_size_horizontal * 0.5
+gopro_radius_vertical   = gopro_size_vertical   * 0.5
+gopro_radius_diagonal   = gopro_size_diagonal   * 0.5
+
+# https://en.wikipedia.org/wiki/Fisheye_lens
+
+equidistant_angle  = lambda radius: math.degrees(radius / gopro_focal_length)
+
+gopro_fov_horizontal = 2.0 * equidistant_angle(gopro_radius_horizontal)
+gopro_fov_vertical   = 2.0 * equidistant_angle(gopro_radius_vertical)
+gopro_fov_diagonal   = 2.0 * equidistant_angle(gopro_radius_diagonal)
+
+print("gopro  fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
+    gopro_fov_horizontal,
+    gopro_fov_vertical,
+    gopro_fov_diagonal))
+
+print("\n--- rectilinear re-projection ---\n")
+
+rectilinear_focal_length = lambda radius: radius * math.tan(math.radians(90.0 - equidistant_angle(radius)))
+
+rectilinear_focal_length_horizontal = rectilinear_focal_length(gopro_radius_horizontal)
+rectilinear_focal_length_vertical   = rectilinear_focal_length(gopro_radius_vertical)
+rectilinear_focal_length_diagonal   = rectilinear_focal_length(gopro_radius_diagonal)
+
+print("linear focal: horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (mm)" % (
+    rectilinear_focal_length_horizontal,
+    rectilinear_focal_length_vertical,
+    rectilinear_focal_length_diagonal))
+
+rectilinear_radius = lambda angle:  rectilinear_focal_length_vertical * math.tan(math.radians(angle))
+rectilinear_angle  = lambda radius: math.degrees(math.atan(radius / rectilinear_focal_length_vertical))
+
+rectilinear_fov_horizontal = 2.0 * rectilinear_angle(gopro_radius_horizontal)
+rectilinear_fov_vertical   = 2.0 * rectilinear_angle(gopro_radius_vertical)
+rectilinear_fov_diagonal   = 2.0 * rectilinear_angle(gopro_radius_diagonal)
+
+print("linear fov  : horizontal = %7.3f, vertical = %7.3f, diagonal = %7.3f (deg)" % (
+    rectilinear_fov_horizontal,
+    rectilinear_fov_vertical,
+    rectilinear_fov_diagonal))
+
+print("\n--- shader parameters ---\n")
+
+print("""// parameters\n
+const vec2  sensor_size              = vec2(%.6f, %.6f);
+const float equidistant_focal_length = %.6f;
+const float rectilinear_focal_length = %.6f;""" % (
+    gopro_size_horizontal, gopro_size_vertical,
+    gopro_focal_length,
+    rectilinear_focal_length_vertical)
+)
+
+print("\n--- output size ---\n")
+
+def print_output_array(array_vertical):
+    array_horizontal = (array_vertical / gopro_array_vertical) * gopro_array_horizontal
+    print("resize: width = %d, height = %d" % (
+        round(array_horizontal / 4.0) * 4,
+        array_vertical))
+
+print_output_array(2160)
+print_output_array(1080)