utils: rkisp1: gen-csc-table: Specify coefficients with full precision

The Rec01, Rec709, Rec2020 and SMTPE 240M standards specify the Cb and
Cr coefficients of the RGB to Y'CbCr conversion matrix using a quotient
of two values. Use the exact same formulas instead of hardcoding the
division results with a lower precision.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Florian Sylvestre <fsylvestre@baylibre.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

utils/rkisp1/gen-csc-table.py

@@ -12,24 +12,24 @@
 
 encodings = {
     'rec601': [
-        [  0.2990,  0.5870,  0.1140 ],
-        [ -0.1687, -0.3313,  0.5    ],
-        [  0.5,    -0.4187, -0.0813 ]
+        [  0.299,          0.587,          0.114         ],
+        [ -0.299 / 1.772, -0.587 / 1.772,  0.886 / 1.772 ],
+        [  0.701 / 1.402, -0.587 / 1.402, -0.114 / 1.402 ]
     ],
     'rec709': [
-        [  0.2126,  0.7152,  0.0722 ],
-        [ -0.1146, -0.3854,  0.5    ],
-        [  0.5,    -0.4542, -0.0458 ]
+        [  0.2126,           0.7152,           0.0722          ],
+        [ -0.2126 / 1.8556, -0.7152 / 1.8556,  0.9278 / 1.8556 ],
+        [  0.7874 / 1.5748, -0.7152 / 1.5748, -0.0722 / 1.5748 ]
     ],
     'rec2020': [
-        [  0.2627,  0.6780,  0.0593 ],
-        [ -0.1396, -0.3604,  0.5    ],
-        [  0.5,    -0.4598, -0.0402 ]
+        [  0.2627,           0.6780,           0.0593          ],
+        [ -0.2627 / 1.8814, -0.6780 / 1.8814,  0.9407 / 1.8814 ],
+        [  0.7373 / 1.4746, -0.6780 / 1.4746, -0.0593 / 1.4746 ],
     ],
     'smpte240m': [
-        [  0.2122,  0.7013,  0.0865 ],
-        [ -0.1161, -0.3839,  0.5    ],
-        [  0.5,    -0.4451, -0.0549 ]
+        [  0.2122,           0.7013,           0.0865          ],
+        [ -0.2122 / 1.8270, -0.7013 / 1.8270,  0.9135 / 1.8270 ],
+        [  0.7878 / 1.5756, -0.7013 / 1.5756, -0.0865 / 1.5756 ],
     ],
 }