So I have been experimenting with OpenCV and extracting a specific portion from an image with python.
My test image is:
[![enter image description here][1]][1]
From this image, I want to draw the contours around that stockpile of soil as follows:
(Note: This has been done in Paint)
[![enter image description here][2]][2]
I have tried following things:
1. Reading the Image and converting it into Grayscale
2. Morphological Transformation and thresholding as follows:
But I am not sure what to do next? How to extract the aforementioned part of the image?
import cv2
img = cv2.imread('Feature Extraction/soil_stockpile_test_image.png',
cv2.IMREAD_GRAYSCALE)
blur = cv2.GaussianBlur(img, (1, 1), 2)
h, w = img.shape[:2]
# Morphological gradient
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (7, 7))
gradient = cv2.morphologyEx(blur, cv2.MORPH_GRADIENT, kernel)
cv2.imshow('Morphological gradient', gradient)
#Contours
thresh = cv2.threshold(img,150, 255,cv2.THRESH_BINARY_INV)[1]
cnts, h = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
cv2.imshow('thresh', thresh)
I tried the histogram back projection method. It somewhat worked but it still shows some unwanted part of the image. I just want the stockpile to be shown in the result.
Here is the code and the resulting image:
# Original Image
orig_img = cv2.imread('Feature Extraction/soil_stockpile_test_image.png')
roi = cv2.imread('Feature Extraction/roi_soil.png')
# HSV Image
hsv_img = cv2.cvtColor(orig_img, cv2.COLOR_BGR2HSV)
hsv_roi = cv2.cvtColor(roi, cv2.COLOR_BGR2HSV)
# Region of Interest
roi_hist = cv2.calcHist([hsv_roi], [0, 1], None, [180, 256], [0, 180, 0, 256])
mask = cv2.calcBackProject([hsv_img], [0, 1], roi_hist, [0, 180, 0, 256], 1)
# Remove Noise
kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5,5))
mask = cv2.filter2D(mask, -1, kernel)
_, mask = cv2.threshold(mask, 210, 255, cv2.THRESH_BINARY)
# Merge and perform bitwise operation
mask = cv2.merge((mask, mask, mask))
result = cv2.bitwise_and(orig_img, mask)
#cv2.imshow('HSV Image', hsv_img)
#cv2.imshow('Region of Interest', roi)
#cv2.imshow('Mask', mask)
cv2.imshow('Result', result)
Result:
[![enter image description here][3]][3]
[1]: https://i.stack.imgur.com/cs5sf.jpg
[2]: https://i.stack.imgur.com/coRgM.jpg
[3]: https://i.stack.imgur.com/UEPPb.png
↧