homework #4

Homework #4Homework #4

Due 2/19/13

1. Color sliders1. Color sliders

Power point

2a. Plotting on color triangle 2a. Plotting on color triangle

M=0

M=1L=0

L=1

S=0

2b-i) The red – yellow colors don’t 2b-i) The red – yellow colors don’t stimulate the S cones so S=0 and all stimulate the S cones so S=0 and all

the colors are on the L-M axisthe colors are on the L-M axisL

MS

2b-ii) 680 nm light – Nearly all the 2b-ii) 680 nm light – Nearly all the light stimulates just the LWS conelight stimulates just the LWS cone

It is not possible to stimulate just the M or It is not possible to stimulate just the M or S cone so the color lines can’t go to the M S cone so the color lines can’t go to the M

or S vertexor S vertex

255, 0, 0

0, 255, 0

0, 0, 255

LWS>MWS

MWS=LWS

SWS>MWS, LWS

2b-iii

2b-iii. Plotting RGB colors on 2b-iii. Plotting RGB colors on color triangle color triangle

M=0

M=1L=0

L=1

S=0

2b-iv) The monochromatic line2b-iv) The monochromatic line

L

MS

The two perpendicular axes The two perpendicular axes which describe the color which describe the color

opponenciesopponencies

Red – green opponency

They result simply from the way the pigment spectra overlap

4) Protanope - no red cones : all 4) Protanope - no red cones : all long wavelength colors are long wavelength colors are

greengreen

λmax = 420, 535nm

Deuteranope - no green cones : Deuteranope - no green cones : all long wavelength colors are all long wavelength colors are

greengreen

λmax = 420, 565 nm

Protanomoly - red pigment Protanomoly - red pigment shifted towards green: some shifted towards green: some colors at long wavelengthscolors at long wavelengths

λmax = 420, 535, 550 nm

Deuteranomoly - green pigment Deuteranomoly - green pigment shifted towards red: some shifted towards red: some

colorscolors

λmax = 420, 554, 565 nm

Tritanopia: the short Tritanopia: the short wavelength colors are more wavelength colors are more

grey to blue and long colors are grey to blue and long colors are redsreds

5) Josh Silver5) Josh Silver

Description of AdspecsDescription of Adspecs

Liquid has n=1.579Liquid has n=1.579

People do pretty well as self-People do pretty well as self-correctingcorrecting

Notes from Lecture 11Notes from Lecture 11

About HW#4

Long Long wavelengthswavelengths

• M=0 S=0 L=1

• Only LWS cone absorbs light

At no At no wavelength does wavelength does

L=0L=0LWS cone absorbs

light over full visible rangeL>0

Forbidden zone

Just because R and G are 0 does not mean M and L are 0

Different spectra can stimulate the S, M and L cones in same way

Computer blue

Laser blue

Third channelThird channel

• Red - Green channel• Blue - Yellow channel

• Sum of all three cones detects lightnessBlack Black --->---> White channel

If LWS cone covers full spectrum, always one cone working to detect light