Scole captcha resolver

Module for solving captcha of Scole journal.

Guide

The main function for solving a captcha is resolve_captcha. It takes a monochrome picture as first argument and an array of "num masks" as second one. It gives a string of an answer or undefined.

Monochrome picture

There is used own class MonochromePicture for that. There are two ways to get object of it: static method from_png or static method from_img.

from_png takes an ArrayBuffer of png file as only argument. from_img takes a HtmlImageElement of captcha image as first argument and an object specifying font color. That object has three fields: red, blue and green, all of which are number from 0 to 255 and represent corresponding RGB component.

Both methods return MonochromePicture if succeeded.

Num masks

Num mask is object of class NumMask. That has four fields: height, width, points and digit. height and width are number that represent corresponding dimension of digit. digit is number of digit which is presented by that num mask. points is an Array of Point objects. Point is just an object with fields x and y of type number.

Examples

From picture on a site:

fetch("https://scole.journal/cpt.a")
    .then(captcha_response => captcha_response.arrayBuffer())
    .then(captcha => {
        const captcha_monochrome_picture = MonochromePicture.from_png(captcha),
            captcha_answer = resolve_captcha(captcha_monochrome_picture, num_masks);
        console.log(captcha_answer);
    });

From picture on a page:

const img = document.querySelector("img"),
    captcha_monochrome_picture = MonochromePicture.from_img(img, {red: 214, green: 191, blue: 168}),
    captcha_answer = resolve_captcha(captcha_monochrome_picture, num_masks);
console.log(captcha_answer);