line_image.js

<!-- node line_image.js input.jpg output.png -->
const HEIGHT = 370;
const WIDTH = 320;

if (process.argv.length < 4) {
    console.log('missing argument.');
    return;
}

var gm = require('gm').subClass({ imageMagick: true });
gm(process.argv[2])
    .fuzz('20%')
    .trim()
    .resize(HEIGHT, WIDTH)
    .extent(HEIGHT, WIDTH)
    .fuzz('10%')
    .fill('#00000000')
    .setDraw('matte', 1, 1, 'floodfill')
    .setDraw('matte', 1, WIDTH - 1, 'floodfill')
    .setDraw('matte', HEIGHT - 1, 1, 'floodfill')
    .setDraw('matte', HEIGHT - 1, WIDTH - 1, 'floodfill')
    .write(process.argv[3], function (err) {
            if (!err) console.log(process.argv[2] + " -> " + process.argv[3]);
    });