Are movies altered to be on Blu-ray?

[wallendo]

I guess it depends on the director's intent. In many movies, the color balance is intentionally altered for artistic effect (e.g., the green tint in The Matrix). These color shifts should not be corrected.

In other cases, the colors of the original film have shifted during the aging process. I suspect most people would want these colors corrected.

I agree that sometimes some reviewers seem to be more obsessed with pretty pixels than the original appearance of the film. Old grainy movies should be grainy, but faded film should be restored (my opinion - it's worth what you paid for it).