PNG_Utils is a PNG decoder and collection of useful functions to read, parse, and edit PNG files in pure JS without the need for Node.

Example

Extracting one 64x64 tile from the below tilesheet:

    function foo(evt) {
        const myPNG = await new png(evt);
        const decompressedData = await myPNG.decompressIDATData();
        const unfilteredData = myPNG.reverseFiltering(decompressedData);
        const subImage = myPNG.subImage(unfilteredData, { x: 64, y: 64 }, { xMargin: 0, yMargin: 0 });
    }

Usage

    //With event
    function foo(evt) {
        const myPNG = await new png(evt);
    }
    //Without event
    function foo(file) {
        const myPNG = await new png(file);
    }

Decompression, unfiltering, and extracting sub-images.

    function foo(evt) {
        const myPNG = await new png(evt);
        const decompressedData = await myPNG.decompressIDATData();
        const unfilteredData = myPNG.reverseFiltering(decompressedData);
        const subImage = myPNG.subImage(unfilteredData, { x: 64, y: 64 }, { xMargin: 0, yMargin: 0 });
    }