wall images not showing correctly

[MOST_WASTED]

hi guys i've recently encountered a problem or i only noticed it now with my images (only for some) or wallpapers to be exact because it only happens when i use them as my wallpaper. here's a screenshot


on the image: u can see the left has parts that look pixely (encircled in red) the one on the right is the actual image both of them are centered so i dont understand why it is suddenly shown that way when used as a wallpaper when its not even stretched or shrunk.
im just not sure what is causing this as i have my resolution on its best and have the color on 32bit RGB, im using aero and have this thing set on best appearance. is this a normal thing? cause i would really feel like a jackass if it was . is it just me?
any advice any help would be appreciated. thanks