Week 2 Solution
Question 1
a,b)
c) There are points in the first triangle that aren’t in the second one, so there are colours on the screen that can’t be printed.
The best solution to this is to map the entire screen gamut (the triangle) into the printer gamut. This changes the colours slightly but leaves the relationship between the colors the same.
Question 2
The light coming out of an LCD display is vertically polarized (see lecture slides), so the sunglasses don’t block it, but if you put your head on its side, or rotate the display 90 degrees (eg with a digital camera to take a picture in portrait orientation), no light is transmitted and the display appears black.
Question 3
| colour | R | G | B | H | S | V |
|---|---|---|---|---|---|---|
| black | 0 | 0 | 0 | 0 | 0 | 0 (H can be anything) |
| white | 1 | 1 | 1 | 0 | 0 | 1 (H can be anything) |
| red | 1 | 0 | 0 | 0 | 1 | 1 |
| yellow | 1 | 1 | 0 | 60 | 1 | 1 |
| green | 0 | 1 | 0 | 120 | 1 | 1 |
| cyan | 0 | 1 | 1 | 180 | 1 | 1 |
| blue | 0 | 0 | 1 | 240 | 1 | 1 |
| magenta | 1 | 0 | 1 | 300 | 1 | 1 |
| brown | .65 | .15 | .15 | 0 | .77 | .65 |
(Conversion formula used to work out the last one)
August 11th, 2008 at 12:22 am
The graph for question 1 looks quite different from the original question. This is not intentional, is it?
For question 3, in my tutorial we got 0, 0.77, 0.65 for brown HSV, which corresponds to the formulas that are on Wikipedia for RGB to HSV conversion. Why is the given solution 0, 0.75, 0.63?
August 14th, 2008 at 4:18 pm
The graph is the one I started with to write the question. I copied the coordinates off the graph, so it might not be exact.
For Q3 I used the colour space applet to do the conversion. But I just tried it again and got 0, 0.0.77 0.64, so I must have copied it wrongly.