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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2022-09-28 02:13:38 +0300
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>2022-09-30 22:30:17 +0300
commitdaec83536d2ce5be7e1e39fb1db1d07ff22de369 (patch)
tree2650c0d451650d474440711b69f6d3c88e4f8b62 /utils/rkisp1/gen-csc-table.py
parent0cd715c4ded3b945e7281421552d185018f96a0c (diff)
utils: rkisp1: gen-csc-table: Add support for inverting the CSC
Add a -i/--invert command line argument to invert the YCbCr encoding and output a YCbCr to RGB matrix. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Diffstat (limited to 'utils/rkisp1/gen-csc-table.py')
-rwxr-xr-xutils/rkisp1/gen-csc-table.py31
1 files changed, 21 insertions, 10 deletions
diff --git a/utils/rkisp1/gen-csc-table.py b/utils/rkisp1/gen-csc-table.py
index 2fb70274..c47f5042 100755
--- a/utils/rkisp1/gen-csc-table.py
+++ b/utils/rkisp1/gen-csc-table.py
@@ -7,6 +7,7 @@
import argparse
import enum
+import numpy as np
import sys
@@ -63,9 +64,8 @@ class Quantization(enum.Enum):
LIMITED = 1
-def scale_coeff(coeff, quantization, luma, precision):
- """Scale a coefficient to the output range dictated by the quantization and
- the precision.
+def scale_coeff(coeff, quantization, luma):
+ """Scale a coefficient to the output range dictated by the quantization.
Parameters
----------
@@ -75,9 +75,6 @@ def scale_coeff(coeff, quantization, luma, precision):
The quantization, either FULL or LIMITED
luma : bool
True if the coefficient corresponds to a luma value, False otherwise
- precision : int
- The desired precision for the scaled coefficient as a number of
- fractional bits
"""
# Assume the input range is 8 bits. The output range is set by the
@@ -91,7 +88,7 @@ def scale_coeff(coeff, quantization, luma, precision):
else:
out_range = 240 - 16
- return coeff * out_range / in_range * (1 << precision)
+ return coeff * out_range / in_range
def round_array(values):
@@ -150,6 +147,8 @@ def main(argv):
description='Generate color space conversion table coefficients with '
'configurable fixed-point precision.'
)
+ parser.add_argument('--invert', '-i', action='store_true',
+ help='Invert the color space conversion (YUV -> RGB)')
parser.add_argument('--precision', '-p', default='Q1.7',
help='The output fixed point precision in Q notation (sign bit excluded)')
parser.add_argument('--quantization', '-q', choices=['full', 'limited'],
@@ -171,13 +170,25 @@ def main(argv):
luma = True
scaled_coeffs = []
for line in encoding:
- line = [scale_coeff(coeff, quantization, luma, precision.fractional) for coeff in line]
+ line = [scale_coeff(coeff, quantization, luma) for coeff in line]
scaled_coeffs.append(line)
luma = False
+ if args.invert:
+ scaled_coeffs = np.linalg.inv(scaled_coeffs)
+
rounded_coeffs = []
for line in scaled_coeffs:
- line = round_array(line)
+ line = [coeff * (1 << precision.fractional) for coeff in line]
+ # For the RGB to YUV conversion, use a rounding method that preserves
+ # the rounded sum of each line to avoid biases and overflow, as the sum
+ # of luma and chroma coefficients should be 1.0 and 0.0 respectively
+ # (in full range). For the YUV to RGB conversion, there is no such
+ # constraint, so use simple rounding.
+ if args.invert:
+ line = [round(coeff) for coeff in line]
+ else:
+ line = round_array(line)
# Convert coefficients to the number of bits selected by the precision.
# Negative values will be turned into positive integers using 2's
@@ -188,7 +199,7 @@ def main(argv):
# Print the result as C code.
nbits = 1 << (precision.total - 1).bit_length()
nbytes = nbits // 4
- print(f'static const u{nbits} rgb2yuv_{args.encoding}_{quantization.name.lower()}_coeffs[] = {{')
+ print(f'static const u{nbits} {"yuv2rgb" if args.invert else "rgb2yuv"}_{args.encoding}_{quantization.name.lower()}_coeffs[] = {{')
for line in rounded_coeffs:
line = [f'0x{coeff:0{nbytes}x}' for coeff in line]