How to do correct pixels

I don not know how to fix camera preview
pixels looking not correct.
what happen, how to fix it
my game resolution 256x144
on a images, on a right side correct pixel, on a left not correct.

https://www.dropbox.com/s/kquziuqedf8xqce/IMG_3013.JPG?dl=0
https://www.dropbox.com/s/mkc9y6a3ydzwphd/IMG_3016.JPG?dl=0