120 lines
4.2 KiB
JavaScript
120 lines
4.2 KiB
JavaScript
"use strict";
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var __importDefault = (this && this.__importDefault) || function (mod) {
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return (mod && mod.__esModule) ? mod : { "default": mod };
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};
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.methods = void 0;
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exports.distance = distance;
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exports.compareHashes = compareHashes;
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const any_base_1 = __importDefault(require("any-base"));
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const phash_js_1 = __importDefault(require("./phash.js"));
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// an array storing the maximum string length of hashes at various bases
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// 0 and 1 do not exist as possible hash lengths
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// prettier-ignore
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const alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_";
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// an array storing the maximum string length of hashes at various bases
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// 0 and 1 do not exist as possible hash lengths
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const maxHashLength = [NaN, NaN];
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for (let i = 2; i < 65; i++) {
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const maxHash = (0, any_base_1.default)(any_base_1.default.BIN, alphabet.slice(0, i))(new Array(64 + 1).join("1"));
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maxHashLength.push(maxHash.length);
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}
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exports.methods = {
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/**
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* Calculates the perceptual hash
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* @returns the perceptual hash
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* @example
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* ```ts
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* import { Jimp } from "jimp";
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*
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* const image = await Jimp.read("test/image.png");
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*
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* image.hash();
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* ```
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*/
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pHash(image) {
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const pHash = new phash_js_1.default();
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return pHash.getHash(image);
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},
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/**
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* Generates a perceptual hash of the image <https://en.wikipedia.org/wiki/Perceptual_hashing>. And pads the string. Can configure base.
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* @param base A number between 2 and 64 representing the base for the hash (e.g. 2 is binary, 10 is decimal, 16 is hex, 64 is base 64). Defaults to 64.
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* @example
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* ```ts
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* import { Jimp } from "jimp";
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*
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* const image = await Jimp.read("test/image.png");
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*
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* image.hash(2); // binary
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* image.hash(64); // base 64
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* ```
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*/
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hash(image, base = 64) {
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if (base < 2 || base > 64) {
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throw new Error("base must be a number between 2 and 64");
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}
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const subAlphabet = alphabet.slice(0, base);
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const pHash = this.pHash(image);
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const maxLength = maxHashLength[base];
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return (0, any_base_1.default)(any_base_1.default.BIN, subAlphabet)(pHash).padStart(maxLength, "0");
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},
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/**
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* Calculates the hamming distance of the current image and a hash based on their perceptual hash
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* @param compareHash hash to compare to
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* @returns a number ranging from 0 to 1, 0 means they are believed to be identical
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* @example
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* ```ts
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* import { Jimp } from "jimp";
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*
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* const image = await Jimp.read("test/image.png");
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*
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* image.distanceFromHash(image.pHash());
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* ```
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*/
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distanceFromHash(image, compareHash) {
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const pHash = new phash_js_1.default();
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const currentHash = pHash.getHash(image);
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return pHash.distance(currentHash, compareHash);
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},
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};
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/**
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* Calculates the hamming distance of two images based on their perceptual hash
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* @param img1 A Jimp image to compare
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* @param img2 A Jimp image to compare
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* @returns A number ranging from 0 to 1, 0 means they are believed to be identical
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* @example
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* ```ts
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* import { Jimp, distance } from "jimp";
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*
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* const image1 = await Jimp.read("test/image.png");
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* const image2 = await Jimp.read("test/image.png");
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*
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* distance(image1, image2); // 0.5
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* ```
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*/
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function distance(img1, img2) {
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const phash = new phash_js_1.default();
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const hash1 = phash.getHash(img1);
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const hash2 = phash.getHash(img2);
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return phash.distance(hash1, hash2);
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}
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/**
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* Calculates the hamming distance of two images based on their perceptual hash
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* @param hash1 A pHash
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* @param hash2 A pHash
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* @returns A number ranging from 0 to 1, 0 means they are believed to be identical
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* @example
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* ```ts
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* import { Jimp, compareHashes } from "jimp";
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*
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* const image1 = await Jimp.read("test/image.png");
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* const image2 = await Jimp.read("test/image.png");
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*
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* compareHashes(image1.pHash(), image2.pHash()); // 0.5
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* ```
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*/
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function compareHashes(hash1, hash2) {
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const phash = new phash_js_1.default();
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return phash.distance(hash1, hash2);
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}
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//# sourceMappingURL=index.js.map
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