When you create a piece of artwork on the computer, you are usually given various choices for saving the artwork. Which one is better? Why do you get JPG artifacts? How should you save? This article will answer these questions.
What do all these file types do?
JPG is the most common file type on the internet because it offers the best trade off of quality for file size. All browsers display JPGs the same, so your artwork will look the same for all visitors. JPGs are fairly small files, but they retain lots of file information - your picture should look the same after you save, as long as you're working in a nicer graphics program like Adobe Photoshop or JASC Paint Shop Pro. These programs allow you to adjust the level of quality/file size manually. Problems arise if you save something in MS Paint because it automatically sets the quality level to zero. This is why JPG artifacts (those nasty little blocks of different colors) appear when you save, but not in your original work. This is why you should never save a JPG in Paint. Use BMP, PNG, or GIF instead.
JPGs are usually used for full-color artwork and photographs.
GIFs are also common online because they are the only file types (aside from Flash movies) that support animations. Any animated smilie or sprite you see will most likely be a GIF. They are supported in all browsers, and they also include transparency.
GIFs run into problems because they can only have, at max, 256 colors. This means that GIFs are not good for photographs or full-color artwork. They are best used as icons, sprite art, and emoticons (particularly ones that animate). These are usually very small files.
PNGs are similar to GIFs, but there is no limit to the number of colors you can have. PNGs also support transparency, except that IE doesn't always display it properly (you may see a gray box around the image instead of no background). These are good for both photographs and sprites.
BMP are large files that retain all their image quality, even after saving in Paint. However, these don't always display on the internet. The files are also very big, so they take a long time to transfer.
PSD and TIF files are very large and will not display on the internet. These are usually used as working files in Photoshop or similar programs. These file types will save your layers, so they're good to keep if you ever want to make changes to your work. TIF is a universal file type, but PSD is proprietary to Photoshop.
What file type should I save in?
If you have Paint only (or similar) - never save in JPG.
For Spriter's Challenges, save your work in BMP or PNG. I can convert
the BMPs to JPG for you. If you save in JPG, you will likely be disqualified
for JPG artifacts.
Good luck saving your files!