ENIMDA

ENtropy-based IMage border Detection Algorithm: detect border or whitespace offset for every side of image, including GIF (first frame only).

.. image:: https://travis-ci.org/embali/enimda-rs.svg?branch=master :alt: https://travis-ci.org/embali/enimda-rs

Algorithm (simplified)

For each side of the image starting from top, rotating image counterclockwise to keep side of interest on top:

• Get upper block 25% of image height
• Get lower block with the same height as the upper one
• Calculate entropy for both blocks and their difference
• Make upper block 1px less
• Repeat from p.2 until we hit image edge
• Border is between blocks with entropy difference maximum

.. image:: https://raw.githubusercontent.com/embali/enimda-rs/master/algorithm.gif :alt: Sliding from center to edge - searching for maximum entropy difference :width: 300 :height: 300

Usage

Find if image has any borders:

.. code-block:: rust

extern crate image;
extern crate enimda;

use std::path::Path;
use image::GenericImage;
use enimda::Enimda;

fn main() {
    let mut im = image::open(&Path::new("source.jpeg")).unwrap();
    let borders = im.enimda(2048, 0.25, 0.5, 1.0, 2048, true);
    println!("{:?}", borders);

    let (w, h) = im.dimensions();
    let cropped = im.sub_image(borders[3] + 1,
                               borders[0] + 1,
                               w - (borders[1] + borders[3] + 2),
                               h - (borders[0] + borders[2] + 2))
        .to_image();
    cropped.save("cropped.jpeg").unwrap();
}

Demo

For demo please refer to ENIMDA Demo <https://github.com/embali/enimda-demo/>_

Also it lives at Picture Instruments <http://picinst.com/>_ as 'Remove borders' instrument