image-sequencer/src/modules/Blur/Blur.js

module.exports = exports = function(pixels, blur) {
    let kernel = kernelGenerator(blur, 1), oldpix = require('lodash').cloneDeep(pixels);
    kernel = flipKernel(kernel);

    for (let i = 0; i < pixels.shape[0]; i++) {
        for (let j = 0; j < pixels.shape[1]; j++) {
            let neighboutPos = getNeighbouringPixelPositions([i, j]);
            let acc = [0.0, 0.0, 0.0, 0.0];
            for (let a = 0; a < kernel.length; a++) {
                for (let b = 0; b < kernel.length; b++) {
                    acc[0] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 0) * kernel[a][b]);
                    acc[1] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 1) * kernel[a][b]);
                    acc[2] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 2) * kernel[a][b]);
                    acc[3] += (oldpix.get(neighboutPos[a][b][0], neighboutPos[a][b][1], 3) * kernel[a][b]);
                }
            }
            pixels.set(i, j, 0, acc[0]);
            pixels.set(i, j, 1, acc[1]);
            pixels.set(i, j, 2, acc[2]);
        }
    }
    return pixels;



    //Generates a 3x3 Gaussian kernel
    function kernelGenerator(sigma, size) {

        /*
        Trying out a variable radius kernel not working as of now
        */
        // const coeff = (1.0/(2.0*Math.PI*sigma*sigma))
        // const expCoeff = -1 * (1.0/2.0 * sigma * sigma)
        // let e = Math.E
        // let result = []
        // for(let i = -1 * size;i<=size;i++){
        //     let arr = []
        //     for(let j= -1 * size;j<=size;j++){
        //         arr.push(coeff * Math.pow(e,expCoeff * ((i * i) + (j*j))))
        //     }
        //     result.push(arr)
        // }
        // let sum = result.reduce((sum,val)=>{
        //     return val.reduce((sumInner,valInner)=>{
        //         return sumInner+valInner
        //     })
        // })
        // result = result.map(arr=>arr.map(val=>(val + 0.0)/(sum + 0.0)))

        // return result

        return [
            [2.0 / 159.0, 4.0 / 159.0, 5.0 / 159.0, 4.0 / 159.0, 2.0 / 159.0],
            [4.0 / 159.0, 9.0 / 159.0, 12.0 / 159.0, 9.0 / 159.0, 4.0 / 159.0],
            [5.0 / 159.0, 12.0 / 159.0, 15.0 / 159.0, 12.0 / 159.0, 5.0 / 159.0],
            [4.0 / 159.0, 9.0 / 159.0, 12.0 / 159.0, 9.0 / 159.0, 4.0 / 159.0],
            [2.0 / 159.0, 4.0 / 159.0, 5.0 / 159.0, 4.0 / 159.0, 2.0 / 159.0]
        ];
    }
    function getNeighbouringPixelPositions(pixelPosition) {
        let x = pixelPosition[0], y = pixelPosition[1], result = [];

        for (let i = -2; i <= 2; i++) {
            let arr = [];
            for (let j = -2; j <= 2; j++)
                arr.push([x + i, y + j]);

            result.push(arr);
        }
        return result;
    }

    function flipKernel(kernel) {
        let result = [];
        for (let i = kernel.length - 1; i >= 0; i--) {
            let arr = [];
            for (let j = kernel[i].length - 1; j >= 0; j--) {
                arr.push(kernel[i][j]);
            }
            result.push(arr);
        }
        return result;
    }
}