Pure Python Box Blur Source.

Filter.py

# Box Blur Algorithm from Gerdus van Zyl <gerdusvanzyl@gmail.com>

# it's a slow.it's not good to realtime stuff. Still it works without any other python library based on C.
# Need pypng(pure tiny python image library) for extractiing pixel array of png file.
# Portable. Just put png.py from pypng to your project with this file.

# This source gonna save your file with name "FINAL.PNG" Reccomend modifying for your project.

import png
import array
import copy
import itertools


class PixelInfo():

    def __init__(self,file):
        self.file= file
        self.image = png.Reader(file)


        self.array = array.array('B')

        for i in list(self.image.asRGBA()[2]):
            self.array.extend(i)

def _boxBlur(self):
    N = 5
    xsum = 0
    xsumar = []
    pixels = self.array
    opixels = copy.copy(pixels)

    stride = self.image.width * 4

    clr = array.array('B', [255, 255, 255, 255])

    w = self.image.width
    h = self.image.height

    pixel = 0

    for rgb in [0, 1, 2]:
        for x in range(0, w):
            # print i," of ",w
            for y in range(0, h):

                hN = N / 2
                offset = (y - hN) * stride + (x - hN) * 4
                if offset < 0: offset = 0
                #pixel = pixels[offset + rgb]
                pixel = pixels[offset + rgb]
                xsumar.append(pixel)

                if len(xsumar) > N:
                    xsumar = xsumar[-N:]

                xsum = 0
                for v in xsumar:
                    xsum += v

                xsum /= len(xsumar)

                pixels[offset + rgb] = xsum
    # x
    for rgb in [0, 1, 2]:
        for y in range(0, h):
            # print i," of ",w
            for x in range(0, w):

                hN = N / 2
                offset = (y - hN) * stride + (x - hN) * 4
                if offset < 0: offset = 0
                pixel = pixels[offset + rgb]

                xsumar.append(pixel)

                if len(xsumar) > N:
                    xsumar = xsumar[-N:]

                xsum = 0
                for v in xsumar:
                    xsum += v

                xsum /= len(xsumar)

                pixels[offset + rgb] = xsum


def _getBlurredImage(pixelInfo):

    _boxBlur(pixelInfo)

    tmp_list = list(pixelInfo.array)

    extracted_pixel_list = [tmp_list[i:i+4] for i in range(0,len(tmp_list),4)]



    EPL = list()

    for i in range (0,pixelInfo.image.height):

        tmplist = []
        for k in range(0,pixelInfo.image.width):
            tmplist.append(extracted_pixel_list[k + i*pixelInfo.image.width])

        EPL.append(tmplist)

    png.from_array(EPL,mode='RGBA',info={'height' : pixelInfo.image.height,'width' : pixelInfo.image.width}).save("FINAL.png")