Method, apparatus, system, and storage medium for detecting information card in image

An apparatus for detecting an information card in an image, comprising:

• a memory;
• and
• a processor coupled to the memory and configured for:
• performing a line detection in an information card image, to obtain two endpoints of a line segment corresponding to each of four sides of the information card;
• generating, according to the two endpoints of the line segment corresponding to each side, a linear equation corresponding to the side;
• obtaining coordinates of four intersection points according to the linear equations corresponding to the four sides of the information card;
• mapping the coordinates of the four intersection points to four corners of a rectangular box of the information card, to obtain a perspective transformation matrix;
• performing perspective transformation on image content encircled by four straight lines represented by the four linear equations according to the perspective transformation matrix to provide transformed image content;
• forming a gradient template according to a layout of information content on the information card;
• and
• using the gradient template to match with the transformed image content and determining, according to a matching result, whether the image content is a correct information card.

A non-transitory computer-readable storage medium containing computer-executable program instructions for, when executed by a processor, performing a method for detecting an information card in an image, the method comprising:

• performing a line detection in an information card image, to obtain two endpoints of a line segment corresponding to each of four sides of the information card;
• generating, according to the two endpoints of the line segment corresponding to each side, a linear equation corresponding to the side;
• obtaining coordinates of four intersection points according to the linear equations corresponding to the four sides of the information card;
• mapping the coordinates of the four intersection points to four corners of a rectangular box of the information card, to obtain a perspective transformation matrix;
• performing perspective transformation on image content encircled by four straight lines represented by the four linear equations according to the perspective transformation matrix to provide transformed image content;
• forming a gradient template according to a layout of information content on the information card;
• and
• using the gradient template to match with the transformed image content and determining, according to a matching result, whether the image content is a correct information card.