CODEWITHSUNDEEP
pythonpython-imaging-libraryopencv
SSBakh
SSBakh

Reputation: 1532

Error when overlaying two images in OpenCV and or PIL

I've tried overlaying two images in openCV both in openCV and in PIL, but to no avail. I'm using a 1000x1000x3 array of np.zeros for the background (aka, a black background) and this random image of my monitor, but I really can't get it to work for some reason unbeknownst to me.

Trying with OpenCV only: (result(if you pay attention, you can see a couple of weird lines and dots in the middle))

base_temp = np.zeros((1000,1000,3))
foreground_temp = cv2.imread('exampleImageThatILinkedAbove.png')

base_temp[offset_y:offset_y+foreground_temp.shape[0], offset_x:offset_x+foreground_temp.shape[1]] = foreground_temp

Trying with PIL: (The result is literally the same as the OpenCV version)

base_temp = cv2.convertScaleAbs(self.base)   #Convert to uint8 for cvtColor
base_temp = cv2.cvtColor(base_temp, cv2.COLOR_BGR2RGB)   #PIL uses RGB and OpenCV uses BGR
base_temp = Image.fromarray(base_temp)    #Convert to PIL Image
foreground_temp = cv2.cvtColor(cv2.convertScaleAbs(self.last_img), cv2.COLOR_BGR2RGB)
foreground_temp = Image.fromarray(foreground_temp)
base_temp.paste(foreground_temp, offset)

I'm using python3.5 and and OpenCV3.4 on Windows 10, if that's any help.

I'd like to avoid any solutions that require saving the cv2 images and then reloading them in another module to convert them but if it's unavoidable that's okay too. Any help would be appreciated!

Upvotes: 0

Views: 307

Answers (1)

Mark Setchell
Mark Setchell

Reputation: 207355

If you check the type of base_temp, you will see it is float64 and that is going to cause you problems when you try to save it as a JPEG which expects unsigned 8-bit values.

So the solution is to create your base_temp image with the correct type:

base_temp = np.zeros((1000,1000,3), dtype=np.uint8)

The complete code and result look like this:

import cv2
import numpy as np
from PIL import Image

# Make black background - not square, so it shows up problems with swapped dimensions
base_temp=np.zeros((768,1024,3),dtype=np.uint8)
foreground_temp=cv2.imread('monitor.png')

# Paste with different x and y offsets so it is clear when indices are swapped
offset_y=80
offset_x=40
base_temp[offset_y:offset_y+foreground_temp.shape[0], offset_x:offset_x+foreground_temp.shape[1]] = foreground_temp

Image.fromarray(base_temp).save('result.png')

enter image description here

Upvotes: 2

Related Questions