Therefore, you may need authorization of the owner before you can use any of the referenced materials. However, you may want more flexibility in viewing graphics, and also the ability to modify them. There are a lot of freeware and low-cost shareware programs for working with graphics. Most of these programs will let you rotate, flip, or crop images, change the brightness and contrast, and produce a number of fairly impressive photographic effects. Many also let you set up automatic slide shows.
Higher resolution is sharper, but the file size increases proportionally.
Higher resolution pictures print better than low-resolution pictures. In fact, the size of an image is often specified in pixels. And on the Internet, that's crucial. JPEG and GIF are both compressed formats, but they have different strengths. The image quality stays the same as you save it.