i have a very little question, what is the value that the following image takes for the pixel (1,3), using the Python matrix convention for the pixel coordinate?
Arrays are accessed with (row, column) indexing.
image_array = np.array([[20, 21, 22, 23, 24], [15, 16, 17, 18, 19], [10, 11, 12, 13, 14], [5, 6, 7, 8, 9], [0, 1, 2, 3, 4]]) print(image_array[1, 3])
This returns 18
does that depends on the way numpy works?
Yes numpy follows a “matrix” convention (row, column) as previously mentioned, I think scikit image too.
Other packages like opencv, or in ImageJ, KNIME… follows a (x, y) convention such that x is along the columns (width) and y along the lines (height).
In ImageJ you can see it in the toolbar when you hover the mouse over the image.
Thanks for answering @LThomas!
I would like to point out that scikit-image has a guide about image coordinates in NumPy here: