How to save image with resolution greater than 1080p?

Question

I'm trying to use Logitech BRIO in 3840x2160 resolution, when I execute the python code, a window opens with the camera image (in 3840x2160), but when I save a frame, the program creates a image in 1920x1080. How can I save the image in 4k high resolution?

I'm using opencv-python==4.1.0.25

import cv2
import time

def main(args):

    CAMERA_PORT = 0

    IMAGEWIDTH = 3840
    IMAGEHEIGHT = 2160

    #Propriedades de configuracao da camera
    # 3 = width da camera, 4 = height da camera
    CAMERA_PROP_WIDTH = 3
    CAMERA_PROP_HEIGHT = 4

    camera = cv2.VideoCapture(CAMERA_PORT)
    camera.set(CAMERA_PROP_WIDTH, IMAGEWIDTH)
    camera.set(CAMERA_PROP_HEIGHT, IMAGEHEIGHT)

    imagePath = "/home/barbosa/Documents/camera-controller/images/image.png"


    while(True):

        retval, image = camera.read()
        cv2.imshow('Foto',image)

        k = cv2.waitKey(100)

        if k == 27:
            break

        elif k == ord('s'):
            cv2.imwrite(imagePath,image)
            break

    cv2.destroyAllWindows()
    camera.release()
    return 0

if __name__ == '__main__':
    import sys
    sys.exit(main(sys.argv))

Answer 1

You can make your own custom resize function to upscale and maintain aspect ratio then save the image. I tested it on my IP camera instead of a webcam.

Here's the resize function

# Resizes a image and maintains aspect ratio
def maintain_aspect_ratio_resize(image, width=None, height=None, inter=cv2.INTER_AREA):
    # Grab the image size and initialize dimensions
    dim = None
    (h, w) = image.shape[:2]

    # Return original image if no need to resize
    if width is None and height is None:
        return image

    # We are resizing height if width is none
    if width is None:
        # Calculate the ratio of the height and construct the dimensions
        r = height / float(h)
        dim = (int(w * r), height)
    # We are resizing width if height is none
    else:
        # Calculate the ratio of the 0idth and construct the dimensions
        r = width / float(w)
        dim = (width, int(h * r))

    # Return the resized image
    return cv2.resize(image, dim, interpolation=inter)

Full code

import cv2
import time

# Resizes a image and maintains aspect ratio
def maintain_aspect_ratio_resize(image, width=None, height=None, inter=cv2.INTER_AREA):
    # Grab the image size and initialize dimensions
    dim = None
    (h, w) = image.shape[:2]

    # Return original image if no need to resize
    if width is None and height is None:
        return image

    # We are resizing height if width is none
    if width is None:
        # Calculate the ratio of the height and construct the dimensions
        r = height / float(h)
        dim = (int(w * r), height)
    # We are resizing width if height is none
    else:
        # Calculate the ratio of the 0idth and construct the dimensions
        r = width / float(w)
        dim = (width, int(h * r))

    # Return the resized image
    return cv2.resize(image, dim, interpolation=inter)

def main(args):

    CAMERA_PORT = 0

    IMAGEWIDTH = 3840
    IMAGEHEIGHT = 2160

    #Propriedades de configuracao da camera
    # 3 = width da camera, 4 = height da camera
    CAMERA_PROP_WIDTH = 3
    CAMERA_PROP_HEIGHT = 4

    camera = cv2.VideoCapture(CAMERA_PORT)
    camera.set(CAMERA_PROP_WIDTH, IMAGEWIDTH)
    camera.set(CAMERA_PROP_HEIGHT, IMAGEHEIGHT)

    imagePath = "/home/barbosa/Documents/camera-controller/images/image.png"

    while(True):

        retval, image = camera.read()
        cv2.imshow('Foto',image)

        k = cv2.waitKey(100)

        if k == 27:
            break

        elif k == ord('s'):
            image = maintain_aspect_ratio_resize(image, width=IMAGEWIDTH)
            cv2.imwrite(imagePath,image)
            break

    cv2.destroyAllWindows()
    camera.release()
    return 0

if __name__ == '__main__':
    import sys
    sys.exit(main(sys.argv))