From 1385b3e6f35dacd8736d6fe40f88bf1a9a3cb72f Mon Sep 17 00:00:00 2001
From: Roz K <roz@rozk.net>
Date: Wed, 17 Sep 2025 20:59:34 +0200
Subject: [PATCH] pixel scale for frame widening

---
 gopro_8:7/compute_gopro_8:7.py  | 36 ---------------------------------
 gopro_8:7/unfish_gopro_8:7.glsl |  3 ++-
 2 files changed, 2 insertions(+), 37 deletions(-)
 delete mode 100644 gopro_8:7/compute_gopro_8:7.py

diff --git a/gopro_8:7/compute_gopro_8:7.py b/gopro_8:7/compute_gopro_8:7.py
deleted file mode 100644
index 2c7df8e..0000000
--- a/gopro_8:7/compute_gopro_8:7.py
+++ /dev/null
@@ -1,36 +0,0 @@
-# RozK
-# Computes fisheye removal parameters for GoPro 11+, 8:7 ratio, without hypersmooth,
-# keeping the vertical FOV and widening the frame to preserve the diagonal FOV
-
-# https://www.bobatkins.com/photography/technical/field_of_view.html
-# https://community.gopro.com/s/article/HERO11-Black-Mini-Digital-Lenses-FOV-Information?language=fr
-
-import math
-
-frame_width = 8
-frame_height = 7
-input_ratio = frame_width / frame_height
-
-input_vertical_fov = 108.0
-input_diagonal_fov = 156.0
-
-input_vertical_length = math.radians(input_vertical_fov * 0.5)
-input_diagonal_length = math.radians(input_diagonal_fov * 0.5)
-
-output_horizontal_length = math.sqrt((input_diagonal_length ** 2) / (input_vertical_length ** 2))
-output_diagonal_length = math.hypot(output_horizontal_length, input_vertical_length)
-output_diagonal_fov = math.degrees(math.atan(output_diagonal_length)) * 2.0
-
-output_ratio = 1.0 / (output_horizontal_length / input_vertical_length)
-
-print("Output FOV   = %f" % output_diagonal_fov)
-print("Output Ratio = %f" % output_ratio)
-print("= Resolutions =====================")
-
-def width_rounded_8(height):
-    width = int(round(height * input_ratio))
-    return ((width + 4) // 8) * 8
-
-print("HD             = %i x 720" % width_rounded_8(720))
-print("Full HD        = %i x 1080" % width_rounded_8(1080))
-print("4K             = %i x 2160" % width_rounded_8(2160))
diff --git a/gopro_8:7/unfish_gopro_8:7.glsl b/gopro_8:7/unfish_gopro_8:7.glsl
index eb6099e..88b8db4 100644
--- a/gopro_8:7/unfish_gopro_8:7.glsl
+++ b/gopro_8:7/unfish_gopro_8:7.glsl
@@ -21,6 +21,7 @@ uniform float pts;
 const vec2 sensor_dimensions = vec2(5.949440, 5.205760);
 const float fisheye_focal_length = 2.92;
 const float rectilinear_focal_length = 2.102263;
+const vec2 pixel_scale = vec2(0.871558, 1.0);
 const int subsampling = 4;
 
 // constants
@@ -37,7 +38,7 @@ vec2 sensor_to_texture;
 
 void initialize() {
     texture_center = myResolution * 0.5;
-    texture_to_sensor = (sensor_dimensions / myResolution);
+    texture_to_sensor = (sensor_dimensions / myResolution) * pixel_scale;
     sensor_to_texture = (myResolution / sensor_dimensions);
 }