Introduction
This was an introductory class in which we discussed the course mechanics and experimented with the AV and computer equipment in the classroom
Diagnostic Test
We took a diagnostic test to help plan out the rest.of the course. The
summary results are: almost everybody is comfortable with data structures;
about one-half of the class understands C++ and classes;
almost nobody understands vector calculus or matrices.
People, Computers, and Images
We discussed the interactions between the three. This course is primarily about computer graphics, writing computer programs which transform numerical descriptions of scenes and objects into digital images. These charts were used to summarize the discussion:
Digital Images
A digital image is just a two-dimensional matrix of numbers, each of which represents a color - which can include shades of gray. To be perceived as an image by a human, uniform, regular patches of the corresponding colors are projected on a screen or printed. These patches are called picture elments or pixels. An inherent resolution limit is imposed by the number of pixels in a digital image. If the image is enlarged without altering the number of pixels, the uniform patches just become larger.
Geomerically Described Images
If the image information is stored not as pixel values, but as geomterical descriptions, then the conversion to pixels doesn't have to happen until the moment the digital image is produced for display. Thus, within the limitations of the projection/printing equipment, these images can be shown at anly level of magnification without the artifacts inherent in digital images. Computer graphics is about how to turn geometrical discriptions into digital images.
Here are images of the Penrose Triangle in four formats; gif (a digital image with 275x300 pixels), an gif enlargement showing the discrete pixels, Postscript and pdf. The Postscript and pdf -- a compressed version of Postscript -- are geometrical descriptions and are only converted to digital images when viewed or printed. Depending on the resolution of your screen or printer, discrete pixel effects (staircasing) may or may not be visible.
Gray Levels
We also showed that the maximum number of gray levels that are significant
in digital images is about 256 so for most purposes, our digital images
can be arrays of type unsigned char.
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