How can I know if the image is in RGB or BGR format?

Question

Is there any way to know in advance if an image used as an input to a system is in RGB or BGR format?

I am using OpenCV with java API and I would like to convert an input image into grayscale or L*a*b* color space, but in OpenCV you have to specify first whether the image you want to convert is in RGB or BGR.

The type of the image I am using is either .jpg or .png.

Answer 1

If your image is a BufferedImage then you can ask for his type with getType(), and test against the several constants (see: BufferedImage).

Answer 2

When you use opencv (imread, VideoCapture), the images are loaded in the BGR color space.

Answer 3

If you are reading in the image file, or you have access to the code that reads in the file, know it is:

• BGR order if you used cv2.imread()
• RGB order if you used mpimg.imread() (assuming import matplotlib.image as mpimg)

If you don't know how the file was opened, the accepted answer BufferedImage is great for Java.
I would like to find a way to do the same in Python!