Have you ever sourced an image??
Take this image to a sourcer
and check it out
Do not try to do anyhing with it.
Then take the same image to
Image Magickô, enter the URL, submit....
Next screen, click on Identify.
The code you saw in source makes all the attributes you see in Identify and more.
Images are made from code...
image software programs generate the code by the settings people use...that code is then used by the PC and it makes an image in the browser. The image is then uploaded and becomes "real".
After output, the image still has the PC "gut" code in it.
PC people can put the image into their computer as the code. This is what a tube is really. It's getting the original code for the image. Then people use the software to color, resize, scale, and change the image in any way they want.
Since webtv has no "hard drive" to read the code of the image we use IM, an open source image program with an on-line interface. It reads the image code and does what it is told by the settings people choose. It uses server based software.
Images may also be hand coded using various programing languages using image software downloaded to a PC or using server based software and your FM. The PC(server) reads the code and generates the image specified. That image is uploaded and becomes "real" and the image retains the PC(server) "gut" code. Most all servers have php enstalled and bundled with that is GD or Graphics Draw. You can hand code your own original images using it.
For more about Graphics Draw and CCP Lessons go here.