Add RGB function block

[noqman]

Hi, I am from Cytron Technologies. We are preparing a guidebook for our upcoming Pico 2 extension board, which includes the OPT4048 sensor.

Our use case requires RGB output, not only the original XYZ tristimulus values. So we have modified the existing library to add features that provide RGB values as well.

Changes as follow:

1. Separated the original cie() logic into two parts:

• A function to get XYZ values after the transformation matrix
• A function to compute CIE chromaticity values
  (RGB conversion requires the XYZ values)

2. Added a normalization function to make XYZ values brightness-independent

3. Added a function to convert normalized XYZ into sRGB values

We’d really appreciate if you could review and approve this PR, so our users can conveniently access the updated support via the official CircuitPython Community Bundle when following our guide.

Please me know if there is any I need to change.

Thanks

[FoamyGuy]

Thanks for adding this functionality! also for cleaning up the lux calculation to make it clearer.

I pushed some commits to fix the pre-commit errors and rename normalizedtosum to normalized_xyz

Looks good me. I tested this successfully with https://www.adafruit.com/product/6335 on Feather TFT S2 10.1.0-beta.1 by pointing it at the boards built-in neopixel lit up various colors using this modified version of the simpletest script from this repo:

import time

import board

from adafruit_opt4048 import OPT4048, ConversionTime, Mode, Range
import neopixel

pixels = neopixel.NeoPixel(board.NEOPIXEL, 1, auto_write=True, brightness=0.2)
pixels.fill(0xff0000)

i2c = board.I2C()  # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C()  # For using the built-in STEMMA QT connector on a microcontroller
sensor = OPT4048(i2c)

sensor.range = Range.AUTO
sensor.conversion_time = ConversionTime.TIME_100MS
sensor.mode = Mode.CONTINUOUS
while True:
    try:
        x, y, lux = sensor.cie
        print(f"CIE x:{x}, y:{y}, lux: {lux}", end=" ")
        print(f"K: {sensor.calculate_color_temperature(x,y)}", end=" ")
        print(f"rgb: {sensor.rgb}")
        time.sleep(1)
    except RuntimeError:
        # CRC check failed while reading data
        pass