Re: Constructed maps (shd.be CHAT)

On 6/22/07, Roger Mills <rfmilly@...> wrote:
> > A vector graphics program combined with a pixel graphics
> > program should be a great help.
>
> Hmm, yes, if I had more than a fleeting idea what those terms meant
Well, here's my shot at a quick explanation:

You probably already know that an image is displayed on a computer
screen as an array of tiny dots (called picture elements or pixels),
each of which can be a different color.  A "pixel" (or "raster")
graphics program stores the image exactly the same way: as a
collection of colored dots.  Which is fine when the dots in the image
map one-to-one to the ones on the display.  If you try to make the
picture bigger, though (for instance, to print it out - a printed
picture usually has a lot more dots than one on the screen), you just
end up with bigger dots.  The extreme result of this scort of
scaling-up is the "pixelation" effect frequently used to obscure
things on TV.

In contrast, a vector graphics program stores a mathematical
representation of the lines and other figures (curves, ellipses)
instead.  Vector graphics scale indefinitely - the more dots, the
closer the drawn lines are to the mathematical ideal.  But
constructing the images is different - a digital camera isn't going to
calculate the equations of all the lines and curves in a scene.
Usually vector graphic images are created with a diagramming/drawing
application like Visio.

Postscript and PDF are fundamentally vector-based descriptions of the
printed page, although you can embed pixel-based imagery as well.
Formats like JPEG and GIF are wholly pixel-based.  PNG is usually
pixel-based but I think it has a subformat for vector images as well.





--
Mark J. Reed <markjreed@...>