Understanding Pixel Dimensions
If posting images on the Internet is something new to you, there are a number of things you need to keep in mind. Uploading pictures that are too tall and wide and pictures that take up too much space is a common mistake for novices. In addition to getting your photo to match a variety of monitor resolutions, you need it to fit with the design of your Web page.
Most people will be viewing your images with a 1024×768 resolution. However, others will be viewing at an even higher resolution of 1280×1024 and others at a lower resolution of 800×600. To make matters worse, the average resolution of the Internet tends to get higher as the years go by.
Today a standard VGA size of 640×480 (pixel width and height) will fit on just about any monitor. If you have an uncrowded Web page and want to display a slightly bigger image, chose a resolution in between 640×480 and 800×600. In order to do this, you will need to resize or resample your photo. As always, rename your resized photo, using the Save As command, so that it does not overwrite and erase your original image.
People can usually download the images you post. While technically they might be breaking the law, there is little anyone can do. And if you make your work public, it is not unusual to get a “flame” e-mail occasionally. A flame is a very critical message. You could, for example, get a message from someone you don't know telling you that you are a terrible photographer who should not put her photos up on the web.
When you save your image, you can also set the amount of compression for a JPEG image and compress it more than usual. You can play with the compression settings, but generally you should use less than 80 percent quality and aim for a file size of around 50KB to 150KB. Once you've done this, you're ready to post your photos online.