Fluorescence – is the light emitted as electrons lose their excess energy while the phosphor is being struck by electrons.

Phosphorescence – is the light emitted by phosphor after electron gun leaves

Persistence – is how long does the phosphor glow after electron gun leaves

Refresh rate of a CRT – number of time per second the image is redrawn. Usually ~60

As refresh rate decreases flicker appears.

Critical Fusion Frequency – is the refresh rate above which a picture stops flickering and fuses into a steady image.

What does CFF depend on:

  1. persistence: as persistence increases, CFF decreases – nonlinear dependency
  2. image intensity
  3. room lighting
  4. wavelengths of emitted light
  5. observer

Read carefully:

Chapters 4.2 and 4.3 Make sure you understand Section 4.3.1

Line equation: y = mx + b, where m = dy/dx

What is parametric representation of the line?

What is aliasing?

Aliasing: side effects that you get when you try to represent something continuous in the finite space. High frequencies masquerading as low frequencies in the reconstructed signal.

Jaggies or staircasing – the result of all-or-nothing approach to drawing lines in which each pixel either is colored or not colored.

Solution: unweighted area sampling – setting intensity proportional to the amount of area covered; only the total amount of overlapped area matters, i.e. a small area in the corner of the pixel contributes just as much as does an equal-sized area near the pixel’s center

And Bressenham’s algorithm.

Study both: Sections 3.2 and 3.17.2

Study Brenssenham’s algorithm

Study polygon scan conversion algorithm!!

Read chapters 3.5 and 3.6

What is Coherence?

Coherence – the fact that primitives often do not change from pixel to pixel within a span or from scan line to scan line. IN general we can just look at the pixels at which changes occur.

Edge coherence occurs along an edge for as many scan lines as intersect the edge. As we move from one can line to the next we can compute the new x intersection of the edge on the basis of the old x intersection.

Scan conversion algorithm for polygons uses both edge coherence to calculate x intersections and scan-line coherence (along with sorting) to calculate spans.

How???