• Source: 迪哥谈AI

• Display:

  • Original picture

    

  • contour picture

  

  • result picture

  

• Procedure:

  • get template for each digit

  • get the contour for the region to be matched

    • the each digit with the same size of the digit template
    • to get the contour of digit region on the card, we can do these steps：
      1. top hat -- which highlight the brighter part e.g. digit\pattern\letter etc.
      2. sobel gradient -- to remain and enforce the edge information
      3. MORPH_CLOSE -- morphological close operation (first dilate then erode), blending the remaining region togather
      4. THRESH_OTSU -- find the suitable threshold automatically, then make it binary, preparing for finding the contour
      5. Selecting the proper contour based on the known size (width/lengtn/ration etc.)

  • How to choose the kernel for morphological operation based on task?

    • Meaning for morphology close operation:

      1. Fill small black holes in the while frontgrond 2.Connect Broken White Areas
      2. Smooth Object Borders

    • 9x3 rectangle kernel: Used for the first close operation, which better to manipulate on a string of horizontal numbers or characters and blend them togather

    • 5x5 square kernel: Further smooth and fill in any small holes or unconnected areas that may still exist after the first operation