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.jpg or .jpeg
.JPG or .JPEG stands for: Joint Photographic Experts Group.
This is one of the most prevalent formats on the web. This is a popular format mainly because you can adjust the compression of the file and it's use of 16 million colors versus the 256 colors in .bmp's and .gif's. By compression I mean you can adjust the quality of the picture versus the size of the file. These are adjusted in inverse proportion to each other, or in other words, the lower the quality the smaller the file. The trick is choosing a happy medium of size versus quality. Usually, 75% of full (25% compression) is a good start. It depends on the fine detail such as lines and small shapes in the picture. This file uses lossey compression that causes some color loss at mild compression and then loss of fine detail at higher compression. The loss of both goes up the more the file is shrunk. Use your graphics editor to change the file size in stages of 10% to find the infamous happy medium. Just keep the undo command handy and remember how many undo's the programs supports. In Polyview, the format converter is under the file tab. It supports .gif, .jpg, .bmp and a host of others and is, overall, easier to use than Image forge.
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.gif
The .gif, for Graphics Interchange Format, is used mainly because of the ease in which it can be used to create animated pictures. Most of the animated banners you see on the web are created in .gif format. A perfect example is my e-mail box. Just hold your mouse over the mailbox for a few seconds to read all the text. I left a border of 1 pixel around it so you can see the edges as the background (done through interleaving) is transparent
It doesn't compress as well as a .jpg, but it's support of interleaving, or the layering of pictures, makes up for this. If you want to try some simple animation, you can use Microsofts Gif Animator available from the Microsoft website. The animation is done just like a movie, by recording frames. The more frames, the smoother the animation. Of course it also makes a bigger file with longer download times as well as taking a while to load into Windows Media Player itself. There's that happy medium I was talking about. This format was created with animation in mind just as the .jpg was created with compression as it's primary goal.
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.bmp
The last file discussed here is the venerable Bit Mapped Image, or .bmp, that Windows uses for the backgrounds on your desktop. If you've worked in Microsoft Paint for Windows, then you have already worked with this simple graphic format. Any picture created in MS Paint, is, by default, a .bmp file. This format creates very large files that use only 256 colors at 5 times the file size as a .jpg. Compare this to the 16 million colors in the .jpg format. While easy to work with, .bmp's are to large for regular use. Lets break this down into real world numbers for a little side by side comparison.
Example: .bmp versus .jpg:
Mandelbrot.bmp contains 481,078 bytes in standard uncompressed form at 800 x 600 pixels (the standard resolution for a 15 inch monitor) with 256 colors. That's 470k! By converting it to a .jpg, it's size is dropped to only 76,819 bytes at 100% resolution in 800 x 600 with 16 million colors. Notice that this is only a straight format change. I performed NO compression on the first .jpg other than the format change itself. Best of all, the was no real degradation in picture quality. Now, if you drop it to 75% resolution (25% compression), it weighs in at a petite 20,602 bytes. And all of this with little loss in overall picture quality.NOTE As mentioned above, the higher the compression, the greater the loss of quality and detail.
mandelbrot.bmp at 100%, 481,078 bytes (470k) 800x600 256 colors
mandelbrot.jpg at 100%, 76,819 bytes (76k) 800x600 16m colors
mandelbrot.jpg at 75%, 20,602 bytes (20k) 800x600 16m colors
On the next page, I'll discuss some the more often used commands to bring out the best in your graphics. I'll also get into some of the lingo used in graphics like 'pixelization', 'blurring' and 'sharpening'. These are used especially when you change the size of a picture. Just click the 'Page 3' button, wake up, quit yawning, and lets make some art!
NOTE
For a great graphics editor, try 'Polyview' or 'Image Forge'. You can get these FREE editors at ZDNet in the down-loads area. Just go to the 'Links' page with the handy dandy FreeWare Menu Bar (that big blue thing floating on the left side of the page) and check out the list under 'software'!
NotePolyview is listed as 'shareware', but I list it as free because I have been using the latest version, updated regularly, for over a year. I still get a nag screen when I turn it on asking me to register, but it still works with nothing disabled.
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