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Bezier Curves & Pixels

The images produced in Drawing programs (CorelDraw, Illustrator, Freehand, Designer etc) are called vectorised graphics. That is, all of the objects shown on the computer monitor are representations of points and their relationship to each other on the work area, each of which is stored in the computer as simple values and mathematical equations depicting:

the relationship between each point and the next point referenced to it,


the position (vector) of each point referenced to a starting corner of the work area.

How all of the points react to each other and are converted to an image suitable for human interaction is based largely on equations discovered by a french mathematician named Bezier, and so we now have the familiar name of `Bezier Curves' applied to most of the objects created in these drawing packages. The Node `handles' displayed on the monitor when adjusting Bezier Curves are a simple interface used by the software to alter the mathematics and display the result in real time as we work. These programs are correctly called DRAWING PROGRAMS and the extensions of drawing programs allow us to apply colour etc. as fills and outlines to the points and mathematicaly recorded areas.

Other objects like Bitmaps (photos etc.) can be included in a drawing page, but as yet cannot be fully manipulated in the drawing program.

Bitmap pictures are stored as a vertical and horizontal array of Pixels and stored information represents the colour of each of these pixels. The resolution of a bitmap picture describes how many of these pixels exist over a set distance, usually horizontally: ie pixels per inch or pixels per centimetre. An unaltered bitmap picture of 300 pixels / inch enlarged by 1000% will therefore still have the same number of pixels across the actual picture area but each represented pixel will cover a larger area.

At such an enlargement, the picture would be of little use for reproduction unless viewed from quite a long distance.

Bitmap or Photo-retouching programs are correctly called PAINTING PROGRAMS.

Vectorised drawings on the other hand can be enlarged as much as desired because, although the above mentioned points on a drawing would be further apart, the relationship of any described line between the points would always be the same. i.e. A single company logo file produced in a Drawing program could be used for a business card, any brochure or poster, or plotting out to a Screen Print stencil 3 metres (9 feet) wide, where as bitmap files would have to be created for every size used if practicable.

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