Weird Diagonal Blurring

[CallumGGibson]

When looking 200% at a noisy image, without lens correction the grain structure looks uniform, however when I turn it on it leaves diagonal blur stripes, only visible at the pixel level. I assume that it has something to do with it stretching cetain parts of the image? See screenshots

[Chuck Uebele · Accepted solution]

Yes, lens correction is going to distort the image - no way around that. Most often it won't be noticeable, but that depends on your lens, and how much correction it needs. At the pixel level, you will see the distortion.

[nealbridgens]

Yeah, patterns form. Add your noise after distortions?