How to save

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HOW TO SAVE:

Ok, we're on a roll! We have learned how to draw - either on our own or thanks to the previous page. Anyone can save using a .bmp format; it saves in 2, 16, 256, and 16million color modes. That's the good news. The bad news is we don't use bitmaps on the net. Why? Huge file sizes! On the net we basically use two file formats; .gif and .jpg. Let's stick with these two and i'll describe the various merits - as i perceive them...

.jpg

variable compression

very compact files

up to 16million colors

most popular on the net

.gif

transparent background

compact files

2, 16, and 256 colors

animation, text, multiple pics in one file

.jpg

variable compression
Yes, you select the amount of compression! That's good, but these kinds of files rely not only on a good compression algorithm but they also discard "un-needed" detail. What is saved is not the whole pic! Part of it goes away - forever. A .jpg can degenerate by saving in this format then pulling the pic up again and re saving. It is not a very good format to use where there are a lot of single pixel wide lines - the lines become details to be discarded!

Here are some examples:


.gif format	.jpg format	.jpg format	.jpg format	.jpg format
707 bytes for 2 colors!	9059 bytes in 256 greys!	2891 bytes in 256 greys!	2125 bytes in 256 greys!	1170 bytes in 256 greys!
STD compression	1% compression.	50% compression.	75% compression.	99% compression

i think you can see the deterioration i was referring to...

very compact files
Those files were all less compact than the .gif format, huh? So where does the .jpg format perform well?

Here are some examples:


.gif format	.jpg format	.jpg format	.jpg format	.jpg format
8132 bytes for 256 colors!	1069 bytes in 16million colors!	2382 bytes in 16million colors!	3269 bytes in 16million colors!	14,581 bytes in 16million colors!
STD compression	99% compression.	75% compression.	50% compression.	1% compression.

At about 75 to 50% compression the resolution usually matches whatever a 256 color .gif will do and this wasn't a very clear copy of the scan! When you have photo-quality it's hard to beat a .jpg!

up to 16million colors
As near as i can figure .jpg's come in two flavors; 256 greys or 16million colors.
most popular on the net
Most pics on the net are photographic quality...

.gif

transparent background
A .gif can have one color that is see-through. In theory you can do a cut-out in .gif format and it will sit on any background. Actually it's best to guess about what color background will be used. It doesn't have to be an exact match though. Usually you can just "smooth" a pic to a light or dark background and it will work pretty good. An exact match always works best though.
compact files
Sometimes more compact than a .jpg, but always more compact than a .bmp!
2, 16, and 256 colors
i think there are even some programs that will save in 4, 8, and 32 color formats. The fewer the details and the fewer the number of colors the better the compaction goes. What you see is what is saved!
animation, text, multiple pics in one file
Ever notice these pics that move? Probably a .gif. There are other ways to animate a pic, but .gif is the easiest way. You can put text in a .gif that will display separate from the pic. You can even put more than one pic per file and either animate or display the pics side-by-side or over-lapping!

Ok, so which is better? Depends on what you are doing. Depends if you need 100% accuracy and in how many colors. As a rule-of-thumb use a .jpg where the colors "blend together and use .gif where there are distinct lines that need to be kept clear and crisp.

R E M E M B E R :

Always go with whichever format gives you the smallest file size and the clarity you need! Keeping file sizes down can make all the difference in how fast your pages load - and if they don't load fast your visitors are going to leave!

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