Exact RGB colors of the 7.3” (2025 Edition) ?

[HollaenderDK]

Anyone know the exact RGB values you need to use to get a clean (no raster) color, when displayed on the eInk screen?
I'm guessing you could create some cleaner looking icons if you primarily used these colors - or ?

[ahellbach]

I'm really not sure if this is even possible, but I approached this exact issue by displaying a test image on the screen and then using a color picker for the closest match. There are still dithering artifacts but it's better than nothing. Also I guess that the correct values depend on your image settings.

pimoroni/inky might offer some clues, but I don't see mentions of the 2025 edition in the drivers. Maybe the "correct" values could be extracted from the drivers for a different spectra 6 display or maybe I'm missing something. Either way, the final values will depend on the individual image settings in inkypi, so I will wait it out and see what happens with this project and the Pimoroni drivers in the next few weeks/months.

[ahellbach]

I just looked into it (https://github.com/pimoroni/inky/blob/main/inky/inky_e673.py)
Keep in mind that these values only display as pure colors with the image settings at default.

BLACK = 0
WHITE = 1
YELLOW = 2
RED = 3
BLUE = 5
GREEN = 6

DESATURATED_PALETTE = [
[0, 0, 0],
[255, 255, 255],
[255, 255, 0],
[255, 0, 0],
[0, 0, 255],
[0, 255, 0],
[255, 255, 255]]

[phattmatt]

@ahellbach Looks like a PR (pimoroni/inky#228) was merged recently to adjust those values:

class Inky:
    """Inky e-Ink Display Driver."""

    BLACK = 0
    WHITE = 1
    YELLOW = 2
    RED = 3
    BLUE = 4
    GREEN = 5

    WIDTH = 0
    HEIGHT = 0

    DESATURATED_PALETTE = [
        [0, 0, 0],
        [255, 255, 255],
        [255, 255, 0],
        [255, 0, 0],
        [0, 0, 255],
        [0, 255, 0],
        [255, 255, 255]]

Note: the BLUE and GREEN have changed to point to the 'correct' array values.

I think this change only affected palette based images, so RGB based images would have worked.

[ahellbach]

I really wanted solid colors in my calendar, so I hacked in a way to preserve solid colors while retaining the rest of the image enhancements. This is a really bad way to do it, but it works for me.

In InkyPi/src/utils/image_utils.py:

def apply_image_enhancement(img, image_settings={}):
    # Ensure image is in RGB
    img = img.convert("RGB")
    original_pixels = img.copy().load()

    # Apply global enhancements
    img = ImageEnhance.Brightness(img).enhance(image_settings.get("brightness", 1.0))
    img = ImageEnhance.Contrast(img).enhance(image_settings.get("contrast", 1.0))
    img = ImageEnhance.Color(img).enhance(image_settings.get("saturation", 1.0))
    img = ImageEnhance.Sharpness(img).enhance(image_settings.get("sharpness", 1.0))

    # After all enhancements, restore protected pixels
    protected_colors = {
        (0, 0, 0),          # Black
        (255, 255, 255),    # White
        (255, 255, 0),      # Yellow
        (255, 0, 0),        # Red
        (0, 0, 255),        # Blue
        (0, 255, 0)         # Green
    }

    pixels = img.load()
    width, height = img.size

    for y in range(height):
        for x in range(width):
            if original_pixels[x, y] in protected_colors:
                pixels[x, y] = original_pixels[x, y]

    return img