Python/OpenCV：使用 cv2.resize() 我得到一个错误

Question

I'm using python 2.7 and opencv.

I'm trying to use:

cv2.resize(src, dst, Size(), 0.5, 0.5, interpolation=cv2.INTER_LINEAR);

taken from here . But when I run this code I get NameError: global name 'Size' is not defined.

Can you help me please?

Answer 1

You are probably looking at the C++ api of resize method.

The python API looks something like this:

dst = cv2.resize(src, dsize)

where

src - Original image
dsize - a tuple defining the final size of the image.

If you want to pass additional parameters then you may use the named parameters of the API as:

dst = cv2.resize(src, dsize, fx = 0.5, fy=0.5, interpolation = cv2.INTER_LINEAR)

Since dsize is required param but if you still want the resize method to calculate the dsize for you then you may pass the param as None .

dst = cv2.resize(src, None, fx = 0.5, fy=0.5)

Answer 2

The previous answer was OK, but I wanted to reuse storage--to resize image to fit into existing storage resized (both 3-dimensional uint8 numpy arrays), I needed to use

ret = cv2.resize(image, dsize=resized.shape[:2][::-1], dst=resized)

Note that the dsize argument is backwards--it's not (rows, columns), but (width, height), hence the [::-1] .

I return ret only to confirm that indeed (ret == resized).all() .

Answer 3

# lets doubled the size of our image/ increasing the size...
img_double_scaled = cv2.resize(img, None, fx = 1.5, fy = 1.5, interpolation = cv2.INTER_CUBIC)