How To Sharpen an image in OpenCV

Question

A basic Google search finds this SO question and what appears to be an excellent answer. When I try, however, it has absolutely no effect on sharpening my blurred image.

Answer 1

For future readers, the code does work it was just that my image was so blurry, the above code had no visible effect!

Answer 2

I think fft deconvolution should be interesting for you: http://web.archive.org/web/20160420171504/http://www.nist.gov/lispix/imlab/FFT/deblur.html

But this algorithm userful if you know blur kernel. If not, then you should google for blind deconvolution algorithm.

Answer 3

In order to make it work for a proper image you can check out both the following approches. I did the coding using OpenCV 3.0.0:

import cv2

x = 'Columbia river.jpg'
img = cv2.imread(x, 1)
cv2.imshow("Original",img)

#---Approach 1---
#---Sharpening filter----
kernel = np.array([[-1,-1,-1], [-1,9,-1], [-1,-1,-1]])
im = cv2.filter2D(img, -1, kernel)
cv2.imshow("Sharpening",im)

#---Approach 2---
aw = cv2.addWeighted(img, 4, cv2.blur(img, (30, 30)), -4, 128)
cv2.imshow("Add_weighted", aw)