iOS Determine the corners of a Business Card in realtime
问题 I want to implement a business card detecting functionality like this app (https://scanbot.io). The camera should detect a business card and automatically take a picture of it (only the business card). My idea was using BradLarson's GPUImage library, detect the corners (using the Harris corner detection algorithm), calculate the biggest rectangle with the corners obtained and crop the image contained inside the rectangle. Here is my code: - (void)setupFilter { videoCamera = [