[FIXED] How to extract object in high resolution images?

Issue

I am having an image as enclosed taken through a DSLR camera but its background is also seen on which the object is placed. I want to crop the object from the background. The image size is (3456,5184,3)

Sample image:

I tried a variety of solutions available ie., .using openCV methods like foreground extraction using grabcut, image thresholding and masking, edge detection with unsatisfactory results.

Please suggest the right approach.

Solution

Here's a method using thresholding + contour extraction

• Grayscale then Gaussian blur
• Otsu's threshold for binary image
• Dilate to connect into a single contour
• Extract ROI with numpy slicing

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After converting to grayscale and Gaussian blurring, we Otsu's threshold

Now we have the desired foreground object in white, so we dilate to connect the contours to form a single contour

Finally we obtain the bounding box coordinates and extract the ROI

import cv2

# Grayscale, Blur, Otsu's threshold then dilate
image = cv2.imread('1.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5,5), 0)
thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)[1]
kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (25,25))
dilate = cv2.dilate(thresh, kernel, iterations=3)

# Extract ROI
x,y,w,h = cv2.boundingRect(dilate)
ROI = image[y:y+h, x:x+w]

cv2.imshow('thresh', thresh)
cv2.imshow('dilate', dilate)
cv2.imshow('ROI', ROI)
cv2.waitKey()

Answered By - nathancy

Answer Checked By - Terry (PHPFixing Volunteer)