|When I added this (741 KB) picture Blogger automatically resized it so that it would fit the screen.|
|This is the same image that I resized myself to 8 KB|
This is because the pictures that you see on the screen are digital representations of the pictures that people have put onto their webpages or emailed to you. Pictures are measured in DPI or dots per inch. In order to make digital pictures small so that they download quickly people often compress their photos. The computer takes out some of the dots in a way that the picture still looks good on screen! This can effect the resolution of the picture (or the quality) so that you cannot drag the picture to a larger size. When you try it becomes little color squares..
Most (all?) digital screens only show up to 72 DPI (or dots per inch). If the picture you are seeing has high resolution (more than 72 DPI) sometimes the picture will look HUGE on your screen. One confusing thing is that many programs (like word) allow you to click on the image and drag the corner to make it smaller. When you do this you are only changing the LOOK of the picture, not the DPI, so even though it looks small it will take a LONG time to download and when someone tries to print the picture it will come out huge.
You cannot make a picture with a low number of dots per inch bigger. It will not look good. Artists (and lots of other people) save both a high quality, high resolution picture and the smaller one that they can use to send to people or post online.
I hope that this is a helpful explanation of images online. If you have questions please post them in the comments. Tomorrow's post will be about FILE SIZES.