sarahlouiseb90@gmail.com wrote:
I resized this image to 1200 x 800 and have just cropped a section to show you.
PART I
Viewed at 100%, I see no "pixelation" or any other distortion of any kind whatsoever.
Only a 100% view (1:1) shows you your true image. At smaller percentage views, pixels have to be discarded; at greater percentages pixels have to be made up (invented) by the software.
With the Retina screen you're bound to see very strange things, unless you're using the latest and greatest versions of Photoshop and of your video card, and utilizing the Retina features of the software.
PART II
JPEG is a lousy, lossy format for maintaining image quality. Every single time you open or create and save a JPEG, the image quality deteriorates, no exceptions. Even at the highest quality of compression.
To take a very low resolution JPEG, like you did, and subject it to such a massive enlargement is to ask for demand trouble. Not only are you also magnifying all the JPEG compression artifacts, but you are "inventing" an inordinate amount of pixels.
If you have to enlarge your images often, start with an image file that has NEVER been a JPEG.
PART III
Photoshop performed superbly in your case. That is a remarkably fine enlargement, especially considering the miserly JPEG you started from. Rejoice!