OpenCV & Python - Image too big to display

Question

I have an image that is 6400 × 3200, while my screen is 1280 x 800. Therefore, the image needs to be resized for display only. I am using Python and OpenCV 2.4.9. According to OpenCV Documentation,

If you need to show an image that is bigger than the screen resolution, you will need to call namedWindow("", WINDOW_NORMAL) before the imshow.

That is what I am doing, but the image is not fitted to the screen, only a portion is shown because it's too big. I've also tried with cv2.resizeWindow, but it doesn't make any difference.

import cv2
cv2.namedWindow("output", cv2.WINDOW_NORMAL)        # Create window with freedom of dimensions
# cv2.resizeWindow("output", 400, 300)              # Resize window to specified dimensions
im = cv2.imread("earth.jpg")                        # Read image
cv2.imshow("output", im)                            # Show image
cv2.waitKey(0)                                      # Display the image infinitely until any keypress

Answer 1

Although I was expecting an automatic solution (fitting to the screen automatically), resizing solves the problem as well.

import cv2
cv2.namedWindow("output", cv2.WINDOW_NORMAL)        # Create window with freedom of dimensions
im = cv2.imread("earth.jpg")                        # Read image
imS = cv2.resize(im, (960, 540))                    # Resize image
cv2.imshow("output", imS)                            # Show image
cv2.waitKey(0)                                      # Display the image infinitely until any keypress

Answer 2

Try this:

image = cv2.imread("img/Demo.jpg")
image = cv2.resize(image,(240,240))

The image is now resized. Displaying it will render in 240x240.

Answer 3

In opencv, cv.namedWindow() just creates a window object as you determine, but not resizing the original image. You can use cv2.resize(img, resolution) to solve the problem.

Here's what it displays, a 740 * 411 resolution image.

image = cv2.imread("740*411.jpg")
cv2.imshow("image", image)
cv2.waitKey(0)
cv2.destroyAllWindows()

Here, it displays a 100 * 200 resolution image after resizing. Remember the resolution parameter use column first then is row.

image = cv2.imread("740*411.jpg")
image = cv2.resize(image, (200, 100))
cv2.imshow("image", image)
cv2.waitKey(0)
cv2.destroyAllWindows()