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# SPDX-License-Identifier: GPL-2.0-or-later
#
# Copyright (C) 2019, Raspberry Pi Ltd
# Copyright (C) 2025, Ideas on Board
#
# Base Lux tuning module
from ..module import Module
import logging
import numpy as np
logger = logging.getLogger(__name__)
class Lux(Module):
type = 'lux'
hr_name = 'Lux (Base)'
out_name = 'GenericLux'
def __init__(self, debug: list):
super().__init__()
self.debug = debug
def calculate_lux_reference_values(self, images):
# The lux calibration is done on a single image. For best effects, the
# image with lux level closest to 1000 is chosen.
imgs = [img for img in images if img.macbeth is not None]
lux_values = [img.lux for img in imgs]
index = lux_values.index(min(lux_values, key=lambda l: abs(1000 - l)))
img = imgs[index]
logger.info(f'Selected image {img.name} for lux calibration')
if img.lux < 50:
logger.warning(f'A Lux level of {img.lux} is very low for proper lux calibration')
ref_y = self.calculate_y(img)
exposure_time = img.exposure
gain = img.againQ8_norm
aperture = 1
logger.info(f'RefY:{ref_y} Exposure time:{exposure_time}µs Gain:{gain} Aperture:{aperture}')
return {'referenceY': ref_y,
'referenceExposureTime': exposure_time,
'referenceAnalogueGain': gain,
'referenceDigitalGain': 1.0,
'referenceLux': img.lux}
def calculate_y(self, img):
max16Bit = 0xffff
# Average over all grey patches.
ap_r = np.mean(img.patches[0][3::4]) / max16Bit
ap_g = (np.mean(img.patches[1][3::4]) + np.mean(img.patches[2][3::4])) / 2 / max16Bit
ap_b = np.mean(img.patches[3][3::4]) / max16Bit
logger.debug(f'Averaged grey patches: Red: {ap_r}, Green: {ap_g}, Blue: {ap_b}')
# Calculate white balance gains.
gr = ap_g / ap_r
gb = ap_g / ap_b
logger.debug(f'WB gains: Red: {gr} Blue: {gb}')
# Calculate the mean Y value of the whole image
a_r = np.mean(img.channels[0]) * gr
a_g = (np.mean(img.channels[1]) + np.mean(img.channels[2])) / 2
a_b = np.mean(img.channels[3]) * gb
y = 0.299 * a_r + 0.587 * a_g + 0.114 * a_b
y /= max16Bit
return y
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