How could do sharpness images?

asked 2019-07-30 12:37:01 -0600

kykodev
1 ●1 ●1 ●2

Hello everyone, I want a sharpness image like a camera. In fact, I find how to blur with cv2.GaussianBlur or cv2.Blur but I want to focus or blur depending on the value that is set. What opencv functions could be done with? I am currently doing it in python and I would like to perform the process as if it were photoshop but I have only found a pillow and it does not give me good results.

I try use:

cv2.GaussianBlur(img,(5,5),0)
cv2.Blur(img, (5,5))

And laplace but i want to do this to color images.

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answered 2019-07-31 16:34:33 -0600

Witek

1156 ●1 ●9 ●19

This actually also surprised me a few years back - there are blurring filters but not sharpening ones...

One way of sharpening an image is doing this:

Mat sharp;
Mat sharpening_kernel = (Mat_<double>(3, 3) << -1, -1, -1,
        -1, 9, -1,
        -1, -1, -1);
filter2D(img, sharp, -1, sharpening_kernel);

The sharpening strength depends on the values of the kernel which should sum up to 1).

Another way is subtracting a smoothed image from its original:

double sigma=1, amount=1;
Mat blurry, sharp;
GaussianBlur(img, blurry, Size(), sigma);
addWeighted(img, 1 + amount, blurry, -amount, 0, sharp);

Play with blur strength and weights for different results.

If you add the following, you will get unsharp mask algorithm, but the differences are not significant or even none with conservative settings:

Mat lowContrastMask = abs(img - blurry) < 5; //experiment with values
sharp = img*(1+amount) + blurry*(-amount); //this is the same as addWeighted - is addWeightd obsolete??
img.copyTo(sharp, lowContrastMask);

The above code is in C++ but you should be able to translate it to Python easily.