Giant picture, terrible quality

November 20, 2012 6:49 PM

Why does this happen: huge sized pictures with terrible image quality.

As an example, this picture of a cat from reddit. It's apparently 3264 x 1840 (huge) but terrible quality even when zoomed out to fit my laptop screen. Compare it to this photo, much smaller at 600 x 450 but so much sharper.

I don't know all that much about photography but I'd guess the first photo was taken with a cellphone camera and the second with a 'real' camera, but is that all there is?

What specifically is happening to produce such horrible pictures so frequently?

posted by 2bucksplus to Computers & Internet (6 answers total)

The exif data on that particular image has been stripped but my guess is that yes, its just a lousy cellphone image. If you've got more examples we might be able to provide a more solid answer.
Also, I hate to nitpick, but those image dimensions equal six megapixels - not a huge image. However, it should be much clearer if produced by modern digital camera.
posted by blaneyphoto at 6:56 PM on November 20, 2012

Sometimes the specific incident that I know is a lousy cellphone photo that is then cropped to just show one part of it. So you get even lousier resolution than you might otherwise. End result: yechh.
posted by jessamyn at 6:57 PM on November 20, 2012

Best answer: It's the megapixel myth. Even "quality" phone cams like that in the iPhone 5 suffer from this dreadfully. Zoom in, and each "pixel" is actually a blurry cluster of dozens. It's simply hard to cram that many pixels on a sensor the size of the head of a nail.
posted by Jimbob at 6:58 PM on November 20, 2012 [3 favorites]

Best answer: Most of the time, it's digital zoom. There's optical zoom on real cameras, where the lens physically moves; and there's digital zoom, which is exactly the same as blowing up a small picture to a larger resolution on your computer, and then cropping it back to the original resolution - you get a lower-quality "zoomed in" version.

Real cameras often have both. I always disable digital zoom because I don't see the point. Cellphone cameras almost never have optical zoom, only digital.
posted by WasabiFlux at 7:14 PM on November 20, 2012 [8 favorites]

Yeah, I suspect it is digital zoom. Also, some people will upsample images that are too small for their intended use (which is basically the same thing as digital zoom, but done after-the-fact). If the original is decent quality, a good algorithm is used and it isn't done to excess, the results can be acceptable, but there are a lot of upsampled images out there that met, at best, only one of those guidelines.
posted by Good Brain at 7:34 PM on November 20, 2012

Best answer: Lens quality also plays a huge part in image resolution - a smartphone may have the computing power to capture lots of pixels, but the functional resolution remains pretty low due to the limitations of the lens.

Here's a PDF with formulas and stuff
posted by girih knot at 9:49 PM on November 20, 2012 [2 favorites]