The article doesn't even go anywhere near what you need to do in order to get an acceptable output. It only shows the absolute basics. If you apply only those to a photo from a phone camera, it will be massively distorted (the effect is smaller, but still present on big cameras).

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cellular 8 hours ago | parent | next [-]

When i worked on image pipeline the images were circular and had to be warped to square. Also the edges of the circular image were darker than the middle, and needed to be brightened.

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card_zero a day ago | parent | prev [-]

"Distorted" makes me think of a fisheye effect or something similar. Unsure if that's what you meant.

	▲	seba_dos1 a day ago \| parent [-]
		That's just one kind of distortion you'll see. There will also be bad pixels, lens shading, excessive noise in low light, various electrical differences across rows and temperatures that need to be compensated... Some (most?) sensors will even correct some of these for you already before handing you "raw" data. Raw formats usually carry "Bayer-filtered linear (well, almost linear) light in device-specific color space", not necessarily "raw unprocessed readings from the sensor array", although some vendors move it slightly more towards the latter than others.