Opening an image data.coins()

Hi all!
In the tutorial plot_circular_elliptical_hough_transform
there is the line:

image = img_as_ubyte(data.coins()[160:230, 70:270])

Could somebody please help me to understand this line? Specially the numbers (ranges?) in brackets are confusing.
Thank you.

This crops a region from the full coins sample image.
see here for details:

Thank you jerome. Now that you answered it seems simple - I should have figured it out on my own!

I am trying to run the Hough-based ellipse detection. It works fine with the image data.coins, but fails with my own images. I suspected, that the “number in brackets when opening the image” was the reason - but cropping shouldn’t have an impact on the function (only shorter runtime).

I posted about this issue before, but nobody answered - probably I provided too much information at the time. :slight_smile:

Any idea, how I could solve the problem?