Welcome to HiResCovers.NET

[ctaulbee]

This came up in a WIP thread and since many I think get confused on the subject of image Resolution or more specifically what it means vs Quality of an image, I put this overview with examples together.

First and foremost 'Resolution' is not a number when you are using it to describe a images quality, resolution is short for "print resolution" or the commonly used DPI which sets the print resolution or dot spacing on a printer.

High resolution and low resolution are terms that generally, when you speak of graphics, the speaker means "Quality" or better to the point "How an image looks".

There is no number for that, one must rely on their eyes to decide is the this image, clean, sharp, detailed, color corrected, levels adjusted and so on.

As a general rule larger images both in pixel count and file size tend to be better "quality wise", that is not guaranteed and of the two file size actually is the best indicator because the larger the file in bytes the more pixel data or image information it contains.

As images are compressed when saved this means all jpegs and pngs have some amount of pixel data that is thrown away, never to be seen again.

So the more compression that is used on a image the smaller the file size will get, this is done to make files more manageable sadly the side effect of that is it destroys the image quality if it's compressed too much because too much pixel info is discarded.

This makes it possible for example, that you could find an image online, on several different sites, in the exact same pixel dimensions on all sites--but for it be very different "quality wise" from site to site, depending on a number of factors including the number of times it may have been re-sized and/or re-saved and at what settings.

Many web sites re-size images as they are uploaded to save space this of course lowers image quality and this is why Google is a poor choice for finding images as it is clueless on what a good image looks like.

The highest quality images come directly from the studio publicly sites as they have been altered the least in most cases.

Here's and example, this is a crop taken from a publicity photo from the studio the original image was a 5000+ pixel 14mb jpg.

This was just cropped and saved from that original image with no compression, it's 2000px and it's 2.47mb in size.


This one is the exact same source image, same crop and is still the same physical size 2000px none of that has been changed but it has been heavily compressed to shrink the file size which is now only 121kb in size.


Notice in the circled area when viewed at 100% the pixels have become very pixelated or "blocky" this is a common indicator of over compression, no specification or number contained in the file can tell you this you just have to look at it with your eyes on a good monitor to see it, the fact the file size is small as I said at the beginning would be a flag but you con't rely on file size either to say for sure if a image is good or bad "quality" wise.

Also notice the loss of detail in the eyebrow and the hair strands on the right side still if you looked at thumbs or scaled down versions like previews on Google or some other image site they would look almost identical, even scaled down to just 50% as they are above they look almost the same, you just can't see the bad stuff until you get the image zoomed up to 100% or viewed at full-size.

Side by side close up.


Another little note some colors are affected more by compression than others, red for example tends to be the worst, notice how the red circle in my example was really affected by the high compression setting in the second image, this is true of all red's in images.

[Bazzah]

Another great explanation C Thanks