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The local difference hash resamples an image into nine columns and eight rows, seventy two luminance samples. Eight adjacent horizontal comparisons per row produce sixty four bits. At four pixels per count the sample bar measures two hundred eighty eight, comparison bits two hundred fifty six and eight unused edge samples thirty two. Average hash instead uses eight by eight samples, also sixty four bits, each compared with their mean. Both hashes produce sixteen hexadecimal characters, not a cryptographic ownership certificate. Images are procedural browser drawings by default. These compact summaries help compare appearance but cannot establish artist identity, consent or legal provenance. Normally similarity equals matching difference bits divided by sixty four. Four differences would leave sixty matching bits, giving ninety three point seven five percent similarity. The recolored preset overrides the output to four differences and ninety two percent, independently of actual difference markers. At three pixels per percent the calculated bar measures two hundred eighty one point two five, assigned output two hundred seventy six and gap one point seven five measures five point two five. Switching to identical art removes this preset override and should compare the same drawings. Keep the assigned preset score separate from actual bit matrix computation, and do not interpret a similarity label as evidence of copying. Each synthetic image has six hundred by four hundred pixels, or two hundred forty thousand. Pixel hotspot and histogram loops advance sixteen bytes, inspecting one out of four pixels: sixty thousand samples. At one pixel of bar per thousand pixels the full image measures two hundred forty, sampled pixels sixty and skipped pixels one hundred eighty. A hotspot is a sampled average RGB delta above the tolerance slider. Although three channel histograms are drawn, reported color overlap uses only red channel bins and clamps the percentage between ten and ninety nine point nine. Native presets, modes, tolerance, reset and JSON operate locally; none of these image statistics verify authorship or infringement.