Remove black background and make transparent from grabcut output in python open cv

Question

I am trying to remove black background from grabcut output using python opencv.

import numpy as np import cv2 img = cv2.imread(r'myfile_1.png') mask = np.zeros(img.shape[:2],np.uint8) bgdModel = np.zeros((1,65),np.float64) fgdModel = np.zeros((1,65),np.float64) rect = (1,1,665,344) 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('img',img) cv2.imwrite('img.png',img) cv2.waitKey(0) cv2.destroyAllWindows() 

Above the code I wrote to save the grabcut output. Please suggest how can I remove the black background and make it transparent?

Answer 1

I achieved this using the following snippet.

 import cv2 file_name = "grab.png" src = cv2.imread(file_name, 1) tmp = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY) _,alpha = cv2.threshold(tmp,0,255,cv2.THRESH_BINARY) b, g, r = cv2.split(src) rgba = [b,g,r, alpha] dst = cv2.merge(rgba,4) cv2.imwrite("test.png", dst) 

Answer 2

This is java code. After using grabcut, the result will be transparent.

 public Bitmap removeBackground(Bitmap bitmap) { //GrabCut part Mat img = new Mat(); Utils.bitmapToMat(bitmap, img); int r = img.rows(); int c = img.cols(); Point p1 = new Point(c / 100, r / 100); Point p2 = new Point(c - c / 100, r - r / 100); Rect rect = new Rect(p1, p2); Mat mask = new Mat(); Mat fgdModel = new Mat(); Mat bgdModel = new Mat(); Mat imgC3 = new Mat(); Imgproc.cvtColor(img, imgC3, Imgproc.COLOR_RGBA2RGB); Imgproc.grabCut(imgC3, mask, rect, bgdModel, fgdModel, 5, Imgproc. GC_INIT_WITH_RECT); Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(3.0)); Core.compare(mask, source/* GC_PR_FGD */, mask, Core.CMP_EQ); //This is important. You must use Scalar(255,255, 255,255), not Scalar(255,255,255) Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255,255)); img.copyTo(foreground, mask); // convert matrix to output bitmap bitmap = Bitmap.createBitmap((int) foreground.size().width, (int) foreground.size().height, Bitmap.Config.ARGB_8888); Utils.matToBitmap(foreground, bitmap); return bitmap; }