imshow just opens a tiny window

edit

That's what I thought too, but

cv2.imshow('Title',C:\\Users\\mlarn\\Downloads\\20170818_171339.jpg)
                    ^
SyntaxError: invalid syntax

That is correct, that will not work. That is not the image, that is the path to the image. imread reads the image into memory. (The variable img in your code) imshow takes the image in memory and displays it.

Oh, okay, I think I understand. Thank you!

So what does the "img" in cv2.imshow('Blah',img) mean?

This works now:

import numpy as np
import cv2



img = cv2.imread('C:\\Users\\mlarn\\Downloads\\20170818_171339.jpg',1)
#cv2.namedWindow('C:\\Users\\mlarn\\Downloads\\20170818_171339.jpg', cv2.WINDOW_NORMAL)
cv2.imshow('Title',img)
cv2.waitKey(0) & 0xFF
cv2.destroyAllWindows()

Also, the biggest problem I think I will have for the project I'm working on is the images I have are Geotiff files with an infrared layer. When I run the above code on one of the Geotif files, I just get a black image that matches the tilted footprint of the image itself. Same thing in Gimp.

Do you have any experience with python?

The line img = cv2.imread(...) takes the image path you give it, reads the image, and stores it in the variable named img. the function imshow(...) takes the name you give it for the window, and a variable containing an image, and displays the image.

The other thing is that the IR layer is probably a 16-bit image. The window divides the values by 256 before showing them, so if the image doesn't fill the full 16 bit range, it looks very dark. Try multiplying your image by a power of 2, like 32, or 64 before you display it.