As you should know, we request that images submitted to this site be under 200KB or as close to that as possible. While the vast majority of artists have no problem sticking with this, with the large numbers of new artists we've been getting lately, here are some tips on how to keep control of the file size of your entries. :)
1) First, check your DPI, or resolution. A lot of scanners will scan at 200 or 300 dpi, assuming correctly that, for more things, more is better. If you intend to ever print your picture, a high dpi is good. HOWEVER, for internet viewing only, all you need is a dpi of about 72 or 96 - the reason is that that is as many as most computer monitors can see! So save a nice high-resolution file if you'll want to print, but your web versions can be lower and no one will be able to tell the difference. In Photoshop, this control is in the 'Image Size' area of the 'Image' menu, or you can adjust settings directly at your scanner, in some cases.
2) Image size! Again, scanners will usually go bigger than is really nessesary for internet viewing. The best size is small enough to fit mostly on the screen at one time, but still big enough to see details. As a general rule, about 600-800 pixels wide should be sufficient, though this will vary by image. Widths in the thousands of pixels, however, will almost always need to be scaled down a bit for easy viewing. It is a very rare image program that doesn't allow some kind of image resizing.
3) JPEG compression is another fairly easy way to trim file size down a bit. First, you should all know that a .JPG will be a LOT smaller than a .BMP file, right? This is because of compression. As you save a file as a jpeg, you will usually get a prompt asking you what quality you want it saved at. Higher quality means less compression, and too much compression can really make a picture look grainy and odd. So don't compress too much, but you do not always need the highest setting for a web version, either. Play around a bit and see how low you can get it before you see a difference.
Hope this helps some artists out. ^_^ If you have comments, suggestions or corrections for this tutorial, or if you would like us to add your own favorite tricks or settings, please email us at firstname.lastname@example.org! :)