Ok. Let's say you have a 4"x4" image at 300dpi. In pixels, that's 1200x1200 pixels. That will make a nice 4"x4" picture on paper, but you don't have to have it like that on the web where 72dpi is common. My monitor has a resolution of 1600x1200 over 16"x12" or 100dpi, and that's not typical. 72dpi is typical for the web. The 1200x1200 image would be too big on the screen and take up lots of bandwidth when you display it.

So you can safely shrink your image to 72dpi (or 100dpi if it makes you feel better) unless it is part of a press kit. And your 4"x4" image at 72dpi will still look as good on screen as the 300dpi version does on paper at the same physical size (4"x4").

*However*, if you try to display the 4"x4" 72dpi picture at a larger resolution (say, 6"x6"), then it will pixelate and won't look as good. Instead, understand the target display size and scale the image down from the highest resolution appropriately (300dpi in this case).

Another thing to look at is the compression and smoothing. Again, Corel is better at this, but if your image has a lot of the same color, then some compression (10-15%) will not really be noticable.

Don't try to compress really small images like thumbnails.

Does that make sense?