Hi! I don’t know much about colors, cameras or photography,
I need to apply some color profiles to .cr2/.cr3 raw images.
I originally got these profiles as .dcp files, which I converted to .json with dcamprof, this is all I got:
{
"UniqueCameraModel": "Canon EOS 250D",
"ProfileName": "Canon EOS 250D",
"ProfileEmbedPolicy": "Allow copying",
"CalibrationIlluminant1": "D55",
"ColorMatrix1": [
[ 0.781000, -0.093400, -0.099900 ],
[ -0.429400, 1.180100, 0.283500 ],
[ -0.119200, 0.253000, 0.567200 ]
]
}
{
"UniqueCameraModel": "Canon EOS 200D",
"ProfileName": "Canon SL2 CPL",
"ProfileEmbedPolicy": "Allow copying",
"CalibrationIlluminant1": "D65",
"ColorMatrix1": [
[ 0.657600, 0.003800, -0.087900 ],
[ -0.519800, 1.259700, 0.292800 ],
[ -0.156800, 0.285600, 0.569400 ]
]
}
I’m then trying to use this data to apply it via python, I’ve tried both profiles, applying the inverse and not inverse Matrix, all the results I got either have a red or a green tint, which I assume is not correct.
profile_a = {
"CalibrationIlluminant1": "D65",
"ColorMatrix1": [
[0.657600, 0.003800, -0.087900],
[-0.519800, 1.259700, 0.292800],
[-0.156800, 0.285600, 0.569400],
],
}
profile_b = {
"CalibrationIlluminant1": "D55",
"ColorMatrix1": [
[0.781000, -0.093400, -0.099900],
[-0.429400, 1.180100, 0.283500],
[-0.119200, 0.253000, 0.567200],
],
}
profiles = [profile_a, profile_b]
with rawpy.imread("a.cr3") as raw:
rgb_cam = raw.postprocess(
output_bps=16,
no_auto_bright=True,
use_camera_wb=True,
gamma=(1, 1),
user_flip=0,
)
rgb_cam = rgb_cam.astype(np.float32) / 65535.0
for i, profile in enumerate(profiles):
illuminant = profile["CalibrationIlluminant1"]
M = profile["ColorMatrix1"]
M_inv = np.linalg.inv(M)
matrices = [M, M_inv]
for j, matrix in enumerate(matrices):
h, w, _ = rgb_cam.shape
matrix = np.array(matrix)
xyz = rgb_cam.reshape(-1, 3) @ matrix.T
xyz = xyz.reshape(h, w, 3)
srgb = colour.XYZ_to_sRGB(
xyz,
illuminant=colour.CCS_ILLUMINANTS["CIE 1931 2 Degree Standard Observer"][illuminant],
)
srgb = np.clip(srgb, 0, 1)
imageio.imwrite(f"output_{i}_{j}.jpg", (srgb * 255).astype(np.uint8))
Any idea what might be wrong? Thanks
