Color Vision #4 Flashcards
CIE A
- BB radiator value
- How is it made
- Set the standard for __
- 2800k (yellowish)
- Gas filled coiled tungsten filament with fused quartz envelope
- Sets standard for illuminants B and C
CIE B
- BB radiator value
- How is it made
- Mimics what kind of light?
- 4800K (yellow –> white)
- Made like CIE A (Gas filled coiled tungsten filament fused with quartz envelope) plus a 1cm thick double cell optical glass container filled with liquid.
- Poorly mimics direct sunlight at 12
CIE C
- BB radiator value
- How is it made
- Mimics what kind of light?
- What is it used for?
- What are alternatives/substitutions to this light?
- 6800K (white –> blue)
- Made like CIE B, but with different liquid chemicals.
- Mimics direct northern sunlight.
- Color vision testing.
- Alternatives include the MacBeth lamp or CIE D65
CIE D65
Fluorescent source, so corrected color temp is 6500k.
Did not come from a standard source.
Acceptable substitute for CIE C
4 types of color vision tests
- Matching.
- Arrangement
- Pseudoisochromatic plates (Color confusion)
- Occupational color tests
Matching color test
- Based on work by Rayleigh
- Finds red/green defects only (Differentiates dichromacy from anomalous trichromacy- Deutan and Protan only)
- Most accurate, expensive, difficult to use
- patient mixes colors to obtain the color of regard.
Arrangement tests
- 50 cm test distance
- includes Farnsworth Munsell 100 hue test. This is a good screener for acquired and congenital defects. Uses chromaticity diagram.
- Time consuming
- Also includes L’anthony and Adams test
Ishihara is a good screener for:
Congenital defects. Doesn’t check blue/yellow.
HRR is a good screener for:
Congenital defects and acquired defects. What we have!
What does each test screen for?
- Matching
- Arrangement
- Ishihara
- HRR
- Red/green
- Acquired and congenital
- Congenital
- Acquired and congenital
How does the Nagel Anomaloscope test for red/green deficiencies?
Type of matching test.
Tests for dichromats by looking at how they match a color to a 590 hue.
- Deuteranopes will do well and match closely to 590. They have a photopic spectral efficiency function closest to normal trichromats and have the most confusion lines.
- Protanopes will lower the brightness when matching red because red colors look dim to them
Tests for anomalous trichromats by looking at how they match a color ratio.
Normal trichromats: 45 is the normal ratio, and 17 is the normal intensity.
Deuteranomalous will shift the ratio lower, closer to the green. Intensity stays the same.
Protanomalous will shift the ratio higher, closer to red. Intensity will decrease.
