How to select/mask this object from black background-CodePudding

I want to crop only the object not the black background. How can it be done it using python / openCV?

I have used the following code, I only need object

import cv2
import numpy as np

# original image
# -1 loads as-is so if it will be 3 or 4 channel as the original
image = cv2.imread('/content/image1.jpg', -1)
# mask defaulting to black for 3-channel and transparent for 4-channel
# (of course replace corners with yours)
mask = np.zeros(image.shape, dtype=np.uint8)
roi_corners = np.array([[(10,10), (300,300), (10,300)]], dtype=np.int32)
# fill the ROI so it doesn't get wiped out when the mask is applied
channel_count = image.shape[2]  # i.e. 3 or 4 depending on your image
ignore_mask_color = (255,)*channel_count
cv2.fillPoly(mask, roi_corners, ignore_mask_color)
# from Masterfool: use cv2.fillConvexPoly if you know it's convex

# apply the mask
masked_image = cv2.bitwise_and(image, mask)

# save the result
cv2.imwrite('image_masked.png', masked_image)

CodePudding user response：

You can do it using the next following code. You can play with the minimum threshold value to achieve better results (I found that 50 works great)

import cv2

image = cv2.imread(PathToYourImageFile)
imageGray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
_, thresh = cv2.threshold(imageGray, 80, 255, cv2.THRESH_BINARY)
b, g, r = cv2.split(image)
rgba = [b, g, r, thresh]
imageResult = cv2.merge(rgba, 4)
cv2.imwrite("ImageResult.png", imageResult)

Result:

CodePudding user response：

You can make the black background transparent as follows.

import cv2

img = cv2.imread("0byhS.jpg", 1)
tmp = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
_,alpha = cv2.threshold(tmp,0,255,cv2.THRESH_BINARY|cv2.THRESH_OTSU)
b, g, r = cv2.split(img)
rgba = [b,g,r, alpha]
dst = cv2.merge(rgba,4)
cv2.imwrite("test.png", dst)
cv2.waitKey(0)