Standard operation of subImageMatch + extended tests

Author: dyte

README.md

@@ -1,2 +1,43 @@
 # matches-subimage
-Lightweight library that finds matches of an image within another image
+
+Lightweight library that finds matches of an image within another image, perfect for visual validation in testing scenarios.
+Heavily inspired by (read: blatantly copied some subroutines from) [pixelmatch](https://github.com/mapbox/pixelmatch), and just like [pixelmatch](https://github.com/mapbox/pixelmatch), its advantages are that it's fast and lightweight, with zero dependencies.
+
+Usage demo:
+```js
+const foundMatch = subImageMatch(img, subImg);
+```
+
+## API
+
+### pixelmatch(img, subImg[, options])
+
+- `img1`, `img2` — Image data of the images to compare (`Buffer`, `Uint8Array` or `Uint8ClampedArray`).
+- `options` is an object literal with only one property currently:
+    - `threshold` — Matching threshold, ranges from `0` to `1`. Smaller values make the comparison more sensitive. `0.1` by default.
+
+Returns a boolean indicating whether or not a match has been found
+
+## Example usage
+
+### Node.js
+
+```js
+const fs = require("fs");
+const PNG = require("pngjs").PNG;
+const subImageMatch = require("subimage-match");
+
+const img = PNG.sync.read(fs.readFileSync("image.png"));
+const subImg = PNG.sync.read(fs.readFileSync("sub_image.png"));
+subImageMatch(img1.data, img2.data, {threshold: 0.1});
+```
+
+## Install
+
+Install with NPM:
+
+```bash
+npm install pixelmatch
+```
+
+## [Changelog](https://github.com/dieterwalckiers/subimage-match/releases)