Applies a generic geometrical transformation to an image

dst = cv.remap(src, map1, map2)
dst = cv.remap(src, map1)
dst = cv.remap(..., 'OptionName',optionValue, ...)

Input

• src Source image.
• map1 The first map of either (x,y) points or just x values of the transformation having the type int16 (2-channels), single (1-channels), or single (2-channels). See cv.convertMaps for details on converting a floating-point representation to fixed-point for speed.
• map2 The second map of y values of the transformation having the type uint16 (1-channel) or single (1-channel), or none (empty map if map1 is (x,y) points), respectively.

In other words, the following map combinations are valid:

• separate floating-point representation: map1 as NxMx1 single matrix, and map2 as NxMx1 single matrix
• combined floating-point representation: map1 as NxMx2 single array, and unspecified/empty map2. This is equivalent to map1=cat(3,map1,map2) from the separate floating-point representation.
• fixed-point representation: map1 as NxMx2 int16 array, and map2 as NxMx1 uint16 matrix, converted from the floating-point representation using cv.convertMaps.

Output

• dst Destination image. It has the same row/column size as map1 and the same type as src.

Options

• Interpolation interpolation method, default 'Linear'. One of:
  • Nearest a nearest-neighbor interpolation
  • Linear a bilinear interpolation (used by default)
  • Cubic a bicubic interpolation over 4x4 pixel neighborhood
  • Lanczos4 a Lanczos interpolation over 8x8 pixel neighborhood
• BorderType Pixel extrapolation method. When 'Transparent', it means that the pixels in the destination image corresponding to the "outliers" in the source image are not modified by the function. default 'Constant'
  • Constant iiiiii|abcdefgh|iiiiiii with some specified i
  • Replicate aaaaaa|abcdefgh|hhhhhhh
  • Reflect fedcba|abcdefgh|hgfedcb
  • Reflect101 gfedcb|abcdefgh|gfedcba
  • Wrap cdefgh|abcdefgh|abcdefg
  • Transparent uvwxyz|absdefgh|ijklmno
  • Default same as 'Reflect101'
• BorderValue Value used in case of a constant border. default 0
• Dst Optional initial image for the output. If not set, it is automatically created by the function. Note that it must match the row/column size of map1 and the type of src, otherwise it is ignored and recreated by the function. This option is only useful when BorderType=Transparent, in which case the transformed image is drawn onto the existing Dst without extrapolating pixels. Not set by default.

The function cv.remap transforms the source image using the specified map:

 dst(x,y) = src(mapX(x,y), mapY(x,y))

where values of pixels with non-integer coordinates are computed using one of available interpolation methods. mapX and mapY can be encoded as separate floating-point maps in map1 and map2 respectively, or interleaved floating-point maps of (x,y) in map1, or fixed-point maps created by using cv.convertMaps. The reason you might want to convert from floating to fixed-point representations of a map is that they can yield much faster (2x) remapping operations. In the converted case, map1 contains pairs (floor(x), floor(y)) and map2 contains indices in a table of interpolation coefficients.