CODEWITHSUNDEEP
pythonpython-3.xopencv
strava
strava

Reputation: 765

Iterating through colourspaces in openCV for python

I am trying to make a simple program that shows me what the first frame of a video looks like when it's converted into the different colourspaces available in openCV.

I am trying to use an iterator like this:

for item in flags:
    arg = 'cv2.' + str(item)
    newCs = cv2.cvtColor(frame, arg)

    cv2.imshow('newCs', newCs)
    # if I press no, destroy
    if cv2.waitKey(0) & 0xFF == ord('n'):
        cv2.destroyAllWindows()
    # if I press yes, save and destroy
    if cv2.waitKey(0) & 0xFF == ord('y'):
       filename = str(item) + '.jpg'
       cv2.imwrite(filename, newCs)
       cv2.destroyAllWindows()

where 'flags' is an array containing all the flags like 'COLOR_BGR2HSV' and arg successfully returns a string that looks like the flag you would enter manually into the function eg. 'cv2.COLOR_BGR2HSV'

This program returns an error, saying that it was expecting an int in place of 'arg'

Is this because what I'm trying to do is impossible, or is there a way of doing this?

Thanks

Upvotes: 0

Views: 420

Answers (1)

ZdaR
ZdaR

Reputation: 22954

The error hints, that second param of cv2.cvtColor(), must be int code which tells the method which conversion formula needs to be invoked. And you are trying to pass a str value where, int is required.

Why would you store COLOR_BGR2HSV as str in a list and later concatenate it with "cv2." to make the situation more complex. You may simply create a list as color_configs = [cv2.COLOR_BGR2GRAY, cv2.COLOR_BGR2HSV, ...] and later iterate it to get the job done.

However, if you have no way to changing that list, then there is a hacky way to do the same, I won't recommend you to follow that in first place. But you may use eval, with taking proper precautions and sanitizing the string input, before calling eval as:

for item in flags:
    mode = 'cv2.' + str(item)
    newCs = cv2.cvtColor(frame, eval(mode))

Upvotes: 1

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