05-07-2020, 03:22 PM
(This post was last modified: 07-09-2020, 01:20 AM by nixer55.
Edit Reason: clarified point
)
Picture size and quality seems to be on our minds recently. Thought I'd start a thread where this can be discussed.
Noticed a few members confused over the difference between image quality - and size. The forum itself has a pony in this race too - such things impact page load times and bandwidth consumption. You may not care, but we have to. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
In the digital image world, 2 measurements we hear about a lot - pixel scale - and pixels per inch (or the metric equivalent). Pixel scale (px) determines the size of a displayed image. Pixels per inch (ppi) determines image quality. This is a generalisation - other factors at work determine quality. Good photographers know this, but I'm not one - lol. But these are the most common metrics over which we have some control. Only to a certain extent, as you'll see. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Throughout this discussion, I'll be using GIMP for illustration and examples. I offer no advice for what you can use for mobile, tablets and the like. GIMP just illustrates the point - you can use Photoshop and other programs to do the same thing.
Take this picture from 2018. Actual size is 4608 X 3456. That works out to 16 megapixels - so pretty big. More importantly - the ppi is 300, which is industry standard for high def. I'll use a direct link - it's a large picture at approximately 6 MB:
https://i.imgur.com/JPwM2iS.jpg
For those with the capability, you can open in a new tab and zoom the picture. Then the quality failings come into play - the focus is not great, and so on. That's the photographer (me) - lol. But here's the big one. Imgur has reduced the ppi - what we'd call the quality - from the original 300 to 72. Here's the original showing the ppi. And the size is peeking out in the bottom background:
Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Now I'll download the pic from Imgur and check again:
Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Huh? It's now 72 ppi! And that won't change if I make it bigger or smaller. If anything, the smaller image will appear to have better quality - because we've got 72 ppi over less of an area. Again - bit of a generalisation - but you get the gist. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
The point of all this meandering - don't equate image quality with size. That's often - more like usually - not the case.
Now ducking for all the inbound comments. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Noticed a few members confused over the difference between image quality - and size. The forum itself has a pony in this race too - such things impact page load times and bandwidth consumption. You may not care, but we have to. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
In the digital image world, 2 measurements we hear about a lot - pixel scale - and pixels per inch (or the metric equivalent). Pixel scale (px) determines the size of a displayed image. Pixels per inch (ppi) determines image quality. This is a generalisation - other factors at work determine quality. Good photographers know this, but I'm not one - lol. But these are the most common metrics over which we have some control. Only to a certain extent, as you'll see. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Throughout this discussion, I'll be using GIMP for illustration and examples. I offer no advice for what you can use for mobile, tablets and the like. GIMP just illustrates the point - you can use Photoshop and other programs to do the same thing.
Take this picture from 2018. Actual size is 4608 X 3456. That works out to 16 megapixels - so pretty big. More importantly - the ppi is 300, which is industry standard for high def. I'll use a direct link - it's a large picture at approximately 6 MB:
https://i.imgur.com/JPwM2iS.jpg
For those with the capability, you can open in a new tab and zoom the picture. Then the quality failings come into play - the focus is not great, and so on. That's the photographer (me) - lol. But here's the big one. Imgur has reduced the ppi - what we'd call the quality - from the original 300 to 72. Here's the original showing the ppi. And the size is peeking out in the bottom background:
Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Now I'll download the pic from Imgur and check again:
Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
Huh? It's now 72 ppi! And that won't change if I make it bigger or smaller. If anything, the smaller image will appear to have better quality - because we've got 72 ppi over less of an area. Again - bit of a generalisation - but you get the gist. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
The point of all this meandering - don't equate image quality with size. That's often - more like usually - not the case.
Now ducking for all the inbound comments. Guests cannot see images in the messages. Please register at the forum by clicking here to see images.
