Laplacian opencv 因 cv2.error 失败：OpenCV(4.1.2)

Question

I am trying to apply laplacian to a median filter output to get a sharper image, by later processing. The code snippet is as below :

img = plt.imread('example.png')
img_res = cv.resize(img,(256,256))
gray_image = cv.cvtColor(img_res, cv.COLOR_BGR2GRAY)
median_img = median_filter(gray_image, 5)
# Calculate the Laplacian
lap_img = cv.Laplacian(median_img,cv.CV_64F)

The input image is a RGB medical image. I am faced with the following error, when running this code:

 cv2.error: OpenCV(4.1.2) C:/projects/opencv-python/opencv/modules/imgproc/src/filter.simd.hpp:3175: error: (-213:The function/feature is not implemented) Unsupported combination of source format (=5), and destination format (=6) in function 'cv::opt_AVX2::getLinearFilter'

This error occurs for any image from the dataset. Could you please point out what could be the issue? The example is followed from this link for grayscale images.

Answer 1

Instead of using two different libraries ( matplotlib and opencv ), stick to using one library at a time while performing image-processing. The reason is because these two libraries use different formats to store images. matplotlib uses RGB convention while opencv uses BGR . My guess is that you're encountering this error due to using matplotlib to load the image, and then performing operations with opencv . Simply, loading the image using cv2.imread() instead of plt.imread() seems to fix the problem

Input -> Output

import cv2
from scipy.ndimage.filters import median_filter
import numpy as np

img = cv2.imread('1.png')
gray_image = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
median_img = median_filter(gray_image, 5)
# Calculate the Laplacian
lap_img = cv2.Laplacian(median_img,cv2.CV_64F).astype(np.uint8)

cv2.imshow('lap_img', lap_img)
cv2.imwrite('lap_img.png', lap_img)
cv2.waitKey()