How the measurements work
Images are decoded locally. A worker reads original-resolution sRGB pixels, without resizing or blending colors. Images up to 262,144 pixels use every pixel; larger images use one deterministic random pixel per grid cell, weighted by cell area. Fully transparent pixels are excluded. Partially transparent pixels contribute proportionally, without a background color. Coverage is average alpha, not a count of nontransparent pixels. Animated images are represented by a decoded frame.
Colors are grouped in 5-bit RGB buckets, then clustered deterministically into up to six RGB families using weighted k-means. Shares are approximate and based on visible sampled pixels. Average RGB is calculated in encoded sRGB; relative luminance uses linearized sRGB and Rec. 709 weights. The histogram has 32 equally spaced luminance bins. Tonal spread is measured with population luminance standard deviation and range, not text accessibility contrast.
Sampling can miss rare colors or extrema. Larger images have approximate statistics; bucketed color families are approximate even when every pixel is read. Shadow/midtone/highlight cutoffs are product-defined bins, not standard exposure categories. Browser decoding and low-alpha rounding can affect results. This prototype reads metadata locally, with GPS hidden until explicitly revealed. Spatial maps are bounded-resolution explorations, not sharpness or quality scores. No semantic predictions.