Cutting a Notch Out of the Visible Spectrum
Dye coatings absorb a thin wavelength band where red and green cone sensitivities overlap.
- ~20nm: Notch width (placeholder spectral range)
- ~570-590nm: Target band (red-green overlap zone)
- Dye-coated: Lens type (absorptive interference filter)
- ~25%: Light loss (total transmitted light reduced)
How the notch filter is chosen
Placeholder: dye formulated to absorb the shared wavelength band cones confuse.
Placeholder: filter targets overlap, not a single missing cone type.
Widening the Gap Between Overlapping Color Signals
Blocking shared wavelengths increases the relative signal difference between two confused hues.
- up to ~45%: Contrast gain (placeholder relative measure)
- Outdoor scenes: Best use case (high-saturation foliage/fruit)
- Low light: Worst use case (reduced light hurts more than helps)
- Perceptual: Effect type (not a physiological change)
Why contrast rises
Placeholder: removing overlap makes remaining signals more separable to the brain.
Placeholder: gain is scene- and lighting-dependent, not constant.
Enhanced Discrimination, Unchanged Retina
The cones themselves still transduce the same limited signal set as before.
- 0: Cone types altered (placeholder — none physically changed)
- Some: Discrimination tasks helped (placeholder subset of color tasks)
- Many: Tasks unaffected (placeholder — fine hue judgments)
- Full: Reversibility (effect vanishes when removed)
What does not change
Placeholder: retina and cone pigments remain exactly as they were before.
Placeholder: filtering light is not the same as adding a cone type.
Two Cones Plus a Filter Is Not Three Working Cones
Normal trichromatic vision draws on three independent spectral channels, not two plus a trick.
- 3: Normal cone channels (placeholder — L, M, S cones)
- 2 (+filter): Deficient channels used (placeholder simplified model)
- Partial: Color space recovered (placeholder subspace only)
- Some: Hue confusions removed (placeholder, not all)
Why the math does not add up
Placeholder: subtracting light cannot recreate a missing independent channel.
Placeholder: glasses reshape input, they do not add a cone dimension.
Setting Honest Expectations for Users and Buyers
Marketing claims of "curing" color blindness overstate what filtering light can do.
- False: Cure claim validity (placeholder — no cure occurs)
- Mixed: User satisfaction reports (placeholder survey summary)
- Aid, not cure: Best framing (placeholder recommended language)
- $50-400: Cost range (placeholder market price range)
Communicating limitations clearly
Placeholder: users should expect situational contrast help, not normal color vision.
Placeholder: informed expectations reduce disappointment and misuse.