cv2.resize

• src – input image.
• dst – output image; it has the size dsize (when it is non-zero) or the size computed from src.size(), fx, and fy; the type of dst is the same as of src.
• dsize –output image size; if it equals zero, it is computed as: 
  dsize = Size(round(fx × src.cols), round(fy × src.rows))
• fx –scale factor along the horizontal axis; when it equals 0, it is computed as
• fy –scale factor along the vertical axis; when it equals 0, it is computed as
• interpolation –interpolation method:

• INTER_NEAREST	a nearest-neighbor interpolation  最近邻插值
  INTER_LINEAR	a bilinear interpolation (used by default)  双线性插值（默认设置）
  INTER_AREA	resampling using pixel area relation. It may be a preferred method for image decimation, as it gives moire’-free results. But when the image is zoomed, it is similar to the INTER_NEAREST method.使用像素区域关系进行重采样。 它可能是图像抽取的首选方法，因为它会产生无云纹理的结果。 但是当图像缩放时，它类似于INTER_NEAREST方法。
  INTER_CUBIC	a bicubic interpolation over 4x4 pixel neighborhood  4x4像素邻域的双三次插值
  INTER_LANCZOS4	a Lanczos interpolation over 8x8 pixel neighborhood  8x8像素邻域的Lanczos插值

resize(...)

    resize(src, dsize[, dst[, fx[, fy[, interpolation]]]]) -> dst

    .   @brief Resizes an image.

    .   

    .   The function resize resizes the image src down to or up to the specified size. Note that the

    .   initial dst type or size are not taken into account. Instead, the size and type are derived from

    .   the `src`,`dsize`,`fx`, and `fy`. If you want to resize src so that it fits the pre-created dst,

    .   you may call the function as follows:

    .   @code

    .   // explicitly specify dsize=dst.size(); fx and fy will be computed from that.

    .   resize(src, dst, dst.size(), 0, 0, interpolation);

    .   @endcode

    .   If you want to decimate the image by factor of 2 in each direction, you can call the function this

    .   way:

    .   @code

    .   // specify fx and fy and let the function compute the destination image size.

    .   resize(src, dst, Size(), 0.5, 0.5, interpolation);

    .   @endcode

    .   To shrink an image, it will generally look best with cv::INTER_AREA interpolation, whereas to

    .   enlarge an image, it will generally look best with cv::INTER_CUBIC (slow) or cv::INTER_LINEAR

    .   (faster but still looks OK).

    .   

    .   @param src input image.

    .   @param dst output image; it has the size dsize (when it is non-zero) or the size computed from

    .   src.size(), fx, and fy; the type of dst is the same as of src.

    .   @param dsize output image size; if it equals zero, it is computed as:

    .   \f[\texttt{dsize = Size(round(fx*src.cols), round(fy*src.rows))}\f]

    .   Either dsize or both fx and fy must be non-zero.

    .   @param fx scale factor along the horizontal axis; when it equals 0, it is computed as

    .   \f[\texttt{(double)dsize.width/src.cols}\f]

    .   @param fy scale factor along the vertical axis; when it equals 0, it is computed as

    .   \f[\texttt{(double)dsize.height/src.rows}\f]

    .   @param interpolation interpolation method, see cv::InterpolationFlags

    .   

    .   @sa  warpAffine, warpPerspective, remap