A photograph is a rough guide to eye colour, not a definitive record. Real physical effects explain why the same eyes can look meaningfully different from one photo — or one room — to the next.
Camera white balance and exposure settings, phone-camera automatic processing, HDR blending, filters, and the calibration of the screen you’re viewing on all independently shift the colour you see — none of them are neutral, unbiased recordings of the light that actually reached the camera.
Clothing and makeup colours near the eyes change perceived eye colour through simultaneous contrast, without the eye itself changing. Pupil size — which shifts with ambient light — changes how much of the iris (and which part of it) is visible, which matters especially for hazel, central heterochromia and sectoral heterochromia.
Sampling a pixel colour from a photo captures the apparent colour in that one photo under those specific conditions — not a fixed, ground-truth biological value. Combined with colour constancy (different observers can genuinely perceive the same eyes differently) and metamerism, this is why Colourwise treats eye-colour classification as inherently somewhat subjective, and never claims a photo can definitively determine someone’s eye colour.