Cant be rescaled without significant loss of quality? I dont really understand this. scaling DOWN loses NO quality if you ask me. scaling up, though it loses no
absolute quality, it lowers the
relative quality.
Scaling down clearly loses quality. What if I scale down to a single pixel? If by quality you mean information per pixel then you may be right, but that's not what most people mean. --
drj
The terms "Vector" vs. "Raster" graphics originally derived from display technology. Vector dislays moved the CRT beam from point to point to draw straight line segments, whereas the CRT beam in a raster display scanned a fixed pattern like a TV. Displaying a circle on a raster display required scan-conversion (determining the points where the scan line intersected the circle), whereas displaying a circle on a vector display required vectorization (fitting many short vectors to approximate the circle). Scaling a vectorized circle meant scaling the vectors, which did not preserve the accuracy of the approximation. To maintain fidelity it was necessary to scale the circle geometrically and then re-vectorize. A circle can similarly be scaled geometrically and then re-scan-converted for a raster display. The approach is perhaps more accurately termed "geometric graphics".
That's true, and perhaps something of this origin of the terms should be included in that artice. But regardless of the origin of the terms, their most common present use is merely to distinguish "scanned" graphics from "object-based" graphics. This is even how the terms are used in modern graphics file format specs, and what they are likely to mean when encountered by our audience. I haven't seen an actual vector CRT since the old Atari coin-op video game "Tempest", but people do talk about things like PDF and SVG as "vector" graphics, and in that context, scalability (i.e., the fact that the image is defined in terms of an ideal that can be rendered to the limits of whatever device is available) is a primary feature (that's even what the "S" in SVG stands for). --
LDC
Here's what the
Microsoft Press Computer Dictionary (3rd ed. 1997) has to say...
- vector graphics images generated from mathematical descriptions that determine the position, length, and direction in which lines are drawn. Objects are created as collections of lines rather than as patterns of individual dots or pixels.
- object-oriented graphics computer graphics that are based on the use of graphics primitives, such as lines, curves, circles, and squares...
The IBM Dictionary of Computing (10th ed. 1994) has:
- vector graphics - see coordinate graphics
- coordinate graphics - Computer graphics in which display images are generated from display commands and coordinate data. Contrast with raster graphics. Synonymous with line graphics.
On the other hand, Robin Williams in Jargon: An Informal Dictionary of Computer Terms (1993) says:
- The term vector graphics means exactly the same thing as object-oriented (or just object) graphics.
I suspect the confusion in terminology is due to people (perhaps unfamiliar with the word "vector") incorrectly using "vector graphics" as an antonym for "raster graphics".
If you think it's worthwhile to retain the older meaning of "vector" (perhaps to ease confusion with math articles about vectors), then perhaps we could have a "vector graphics" page with something like "The term
vector graphics is commonly used today as a synonym for [object graphics]
?, though originally it referred to...", and the establish a Wikipedia style guideline to use "object graphics" exclusively. My hesitation to do this is that the misuse of the term really is well-entrenched, and it might be more confusing to use to "correct" term. --LDC
I definitely think the original meaning and context should be included, if only for historical reference. Whether we should attempt to discourage the use of the term in its new sense in favor of "object graphics", I don't know.
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