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how to measure the size of object?

asked 2018-11-28 23:36:04 -0500

processed image after color thresholding

After tweaking the HSV values i'm able to achieve this result, now moving ahead i tried the canny edge detection but it doesn't produce any satisfactory result, My goal is to measure the size of plant. Any idea how do move ahead from this?

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you have a mask now, do findContours, than get the biggest one by minAreaRect or contourArea.

blues gravatar imageblues ( 2018-11-29 04:35:07 -0500 )edit

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answered 2018-12-01 09:58:23 -0500

supra56 gravatar image

updated 2018-12-01 10:27:47 -0500

!/usr/bin/env python3

#Raspberry pi 3B+, debian Strect, kernel 4.19.5 v7
#OpenCV 4.0-pre
#Date 1st December, 2018

import cv2
import numpy as np

if __name__ == '__main__' :

    # Read image
    im = cv2.imread("leaf.jpg")

    # Select ROI
    fromCenter = False
    r = cv2.selectROI(im, fromCenter )

    # Crop image
    imCrop = im[int(r[1]):int(r[1]+r[3]), int(r[0]):int(r[0]+r[2])]

    cv2.imwrite('leaf2.jpg', imCrop) 
    # Display cropped image
    cv2.imshow("Image", imCrop)

Drag rectangle to specify area. Then press space-bar to see second window. leaf2

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thanks for the response @supra56, I think measuring the size of plant in pixels would be good idea. like counting the number of pixels Black & blue would give a clear indication of size of plant.

anuragchaudhary004 gravatar imageanuragchaudhary004 ( 2018-12-04 03:49:20 -0500 )edit
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Asked: 2018-11-28 23:36:04 -0500

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Last updated: Dec 01