Box Blur Algorithm –
Box blur
Note: For each 3 * 3 pixel matrix there is one blurred pixel calculated as above.
Explanation:
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def square_matrix(square): """ This function will calculate the value x (i.e. blurred pixel value) for each 3 * 3 blur image. """ tot_sum = 0 # Calculate sum of all the pixels in 3 * 3 matrix for i in range(3): for j in range(3): tot_sum += square[i][j] return tot_sum // 9 # return the average of the sum of pixels def boxBlur(image): """ This function will calculate the blurred image for given n * n image. """ square = [] # This will store the 3 * 3 matrix # which will be used to find its blurred pixel square_row = [] # This will store one row of a 3 * 3 matrix and # will be appended in square blur_row = [] # Here we will store the resulting blurred # pixels possible in one row # and will append this in the blur_img blur_img = [] # This is the resulting blurred image # number of rows in the given image n_rows = len(image) # number of columns in the given image n_col = len(image[0]) # rp is row pointer and cp is column pointer rp, cp = 0, 0 # This while loop will be used to # calculate all the blurred pixel in the first row while rp <= n_rows - 3: while cp <= n_col-3: for i in range(rp, rp + 3): for j in range(cp, cp + 3): # append all the pixels in a row of 3 * 3 matrix square_row.append(image[i][j]) # append the row in the square i.e. 3 * 3 matrix square.append(square_row) square_row = [] # calculate the blurred pixel for given 3 * 3 matrix # i.e. square and append it in blur_row blur_row.append(square_matrix(square)) square = [] # increase the column pointer cp = cp + 1 # append the blur_row in blur_image blur_img.append(blur_row) blur_row = [] rp = rp + 1 # increase row pointer cp = 0 # start column pointer from 0 again # Return the resulting pixel matrix return blur_img # Driver code image = [[7, 4, 0, 1], [5, 6, 2, 2], [6, 10, 7, 8], [1, 4, 2, 0]] print(boxBlur(image)) |
Output:
[[5, 4], [4, 4]]
image = [[36, 0, 18, 9], [27, 54, 9, 0], [81, 63, 72, 45]] print(boxBlur(image)) |
Output:
[[40, 30]]
Further Read: