Help to choose an opencv module/method

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Hi, I have gone a long way with tutorials and simple manipulations like 'blur', 'threshold', 'bitwise_and' with masks but I am just a monkey following along. When it comes to something new I cant even frame the question much less navigate the vast library available. So I am seeking some suggestions as to what, if any, methods could achieve the following I am currently getting from the input to the output by simply looping the array, unfortunately my Raspberry Pi cant keep up with this in python.

Step 1 is going bottom-to-top to eliminate clear (white) space thats basically an island

Step 2 is going left-to-right to eliminate clear (white) space thats too narrow.

I have some avis that show the progress but I cant load those here.