python - OpenCV remove background

Question

I am trying to remove the background of some images, tweaking some values and using some methods like morphologyEx gives me an aceptable result but some holes still remaining, in this last case, the holes doesn't fill even iterating on every contour and drawing it with -1. I can see that threshold image is really good, making the whole shape with lines, but I don't know how to continue...

Update I've changed my code so I get better results but I'm still getting some holes... If I could fill theese holes, the script would be perfect.

def get_contrasted(image, type="dark", level=3):
    maxIntensity = 255.0 # depends on dtype of image data
    phi = 1
    theta = 1

    if type == "light":
        newImage0 = (maxIntensity/phi)*(image/(maxIntensity/theta))**0.5
        newImage0 = array(newImage0,dtype=uint8)
        return newImage0
    elif type == "dark":
        newImage1 = (maxIntensity/phi)*(image/(maxIntensity/theta))**level
        newImage1 = array(newImage1,dtype=uint8)

        return newImage1

def sharp(image, level=3):
    f = cv2.GaussianBlur(image, (level,level), level)
    f = cv2.addWeighted(image, 1.5, f, -0.5, 0)
    return f

original_image = imread('imagen.jpg')
# 1 Convert to gray & Normalize
gray_img = cv2.cvtColor(original_image, cv2.COLOR_BGR2GRAY)
gray_img = sharp(get_contrasted(gray_img))
gray_img = normalize(gray_img, None, 0, 255, NORM_MINMAX, CV_8UC1)
imshow("Gray", gray_img)

# 2 Find Threshold
gray_blur = cv2.GaussianBlur(gray_img, (7, 7), 0)
adapt_thresh_im = cv2.adaptiveThreshold(gray_blur, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY_INV, 11, 1)
max_thresh, thresh_im = cv2.threshold(gray_img, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)
thresh = cv2.bitwise_or(adapt_thresh_im, thresh_im)

# 3 Dilate
gray = cv2.Canny(thresh, 88, 400, apertureSize=3)
gray = cv2.dilate(gray, None, iterations=8)
gray = cv2.erode(gray, None, iterations=8)
imshow("Trheshold", gray)

# 4 Flood
contours, _ = cv2.findContours(gray, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
contour_info = []
for c in contours:
    contour_info.append((
        c,
        cv2.isContourConvex(c),
        cv2.contourArea(c),
    ))
contour_info = sorted(contour_info, key=lambda c: c[2], reverse=True)
max_contour = contour_info[0]
holes = np.zeros(gray_img.shape, np.uint8)
drawContours(holes, max_contour, 0, 255, -1)
imshow("Holes", holes)

mask = cv2.GaussianBlur(holes, (15, 15), 0)
mask = np.dstack([mask] * 3)  # Create 3-channel alpha mask

mask = mask.astype('float32') / 255.0  # Use float matrices,
img = original_image.astype('float32') / 255.0  # for easy blending
masked = (mask * img) + ((1 - mask) * (0,0,1))  # Blend
masked = (masked * 255).astype('uint8')

imshow("Maked", masked)
waitKey()

0 Original

1 Threshold

2 Holes

3 Final Image

Answer 1

As I was tackling the same issue, and found a solution in Python (with opencv2), thought of just sharing this here as well. Hope it helps.

import numpy as np
import cv2

cv2.namedWindow('image', cv2.WINDOW_NORMAL)

#Load the Image
imgo = cv2.imread('koAl2.jpg')
height, width = imgo.shape[:2]

#Create a mask holder
mask = np.zeros(imgo.shape[:2],np.uint8)

#Grab Cut the object
bgdModel = np.zeros((1,65),np.float64)
fgdModel = np.zeros((1,65),np.float64)

#Hard Coding the Rect The object must lie within this rect.
rect = (10,10,width-30,height-30)
cv2.grabCut(imgo,mask,rect,bgdModel,fgdModel,5,cv2.GC_INIT_WITH_RECT)
mask = np.where((mask==2)|(mask==0),0,1).astype('uint8')
img1 = imgo*mask[:,:,np.newaxis]

#Get the background
background = imgo - img1

#Change all pixels in the background that are not black to white
background[np.where((background > [0,0,0]).all(axis = 2))] = [255,255,255]

#Add the background and the image
final = background + img1

#To be done - Smoothening the edges

cv2.imshow('image', final )

k = cv2.waitKey(0)

if k==27:
    cv2.destroyAllWindows()