Forms a border around an image.

dst = cv.copyMakeBorder(src, top, bottom, left, right)
dst = cv.copyMakeBorder(src, [top, bottom, left, right])
[...] = cv.copyMakeBorder(..., 'OptionName', optionValue, ...)

Input

• src Source image.
• top, bottom, left, right Parameter specifying how many pixels in each direction from the source image rectangle to extrapolate. For example, top=1, bottom=1, left=1, right=1 mean that 1 pixel-wide border needs to be built.

Output

• dst Destination image of the same type as src and the size [size(src,1)+top+bottom, size(src,2)+left+right, size(src,3)].

Options

• BorderType Border type, one of:
  • Constant iiiiii|abcdefgh|iiiiiii with some specified i
  • Replicate aaaaaa|abcdefgh|hhhhhhh
  • Reflect fedcba|abcdefgh|hgfedcb
  • Reflect101 gfedcb|abcdefgh|gfedcba
  • Wrap cdefgh|abcdefgh|abcdefg
  • Default same as 'Reflect101' (default)
• Value Border value when BorderType is 'Constant'. default zeros

The function copies the source image into the middle of the destination image. The areas to the left, to the right, above and below the copied source image will be filled with extrapolated pixels. This is not what filtering functions based on it do (they extrapolate pixels on-fly), but what other more complex functions, including your own, may do to simplify image boundary handling.