How to remove area of interest from the background of an image?

Question

I am starting to work with image processing in pattern recognition, and I need to do pre-processing of the images I will use. First, I need to highlight the region of interest from the background of the image, can anyone tell me what is the best technique for this? I’m using opencv plus python for this procedure.

Second, I need to identify the colors of this region of interest and plot a 3d chart.

Answer 1

To extract you can use the Grab Cut opencv

A example can be seen in the tutorial "Interactive Foreground Extraction using Grabcut Algorithm"

Code

Using the example code:

import numpy as np
import cv2
from matplotlib import pyplot as plt

img = cv2.imread('C:\\Users\\Desktop\\teste\\FHB9o.jpg')

mask = np.zeros(img.shape[:2],np.uint8)

bgdModel = np.zeros((1,65),np.float64)
fgdModel = np.zeros((1,65),np.float64)

rect = (10,10,45,45)
cv2.grabCut(img,mask,rect,bgdModel,fgdModel,5,cv2.GC_INIT_WITH_RECT)

mask2 = np.where((mask==2)|(mask==0),0,1).astype('uint8')
img = img*mask2[:,:,np.newaxis]
cv2.imshow('Imagem', img)
cv2.waitKey(0)
cv2.imwrite('C:\\Users\\Desktop\\teste\\resultado.jpg', img)
plt.imshow(img),plt.colorbar(),plt.show()

Upshot

Observing

In this case the rectangular ROI (Region of Interest) is fixed. If the images have variation in the location of the object that needs to be extracted, a dynamic ROI needs to be created, where the contours will be the points that will determine the coordinates of the dynamic ROI.