For example: Say I have an image that is going to be displayed at 1000px wide.
I want to optimize my site for retina displays, but the largest resolution image I have to put here is only 1900pixel wide.
Is there any unwanted visual effect to scaling down the image by unusual percentages? eg. A 1900pixel wide image being displayed at 1000px wide on a retina device, instead of a 2000pixel wide image.