Contrast Ratio Paper-Screen Reading Comfort Checker
Signed paper/screen luminance transition log-ratio against explicit caller comfort policy, not WCAG text contrast or glare diagnosis. Caller independently establishes matching units, evidence, method edition and applicability; output is not compliance, diagnosis, work-safety approval, geological identity or validated hazard prediction.
Description
Paper-to-screen luminance can be compared through a signed natural-log ratio.
Paper-to-screen luminance can be compared through a signed natural-log ratio.1
Its magnitude measures relative brightness under the supplied criterion rather than an accessibility contrast ratio. Use this tool to calculate contrast Ratio Paper-Screen Reading Comfort Checker from the supplied measurements and assumptions.
When to use Contrast Ratio Paper-Screen Reading Comfort Checker
Use this tool to calculate contrast Ratio Paper-Screen Reading Comfort Checker from the supplied measurements and assumptions. Establish the observation protocol, units, task and reference population or review criterion before entering measurements.
How to use Contrast Ratio Paper-Screen Reading Comfort Checker and understand its results
- Establish the observation protocol, units, task and reference population or review criterion before entering measurements.
- Enter observedPaperLuminance, observedScreenLuminance, callerMaxAbsoluteLogRatio, using the field meanings and rules below, then run the tool.
- Read signedPaperScreenLogRatio, callerContrastReview. Interpret the fields using their units, signs and evidence conventions below.
- If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| observedPaperLuminance | Observed paper luminance | number | Required |
| observedScreenLuminance | Observed screen luminance | number | Required |
| callerMaxAbsoluteLogRatio | Caller max absolute log ratio | number | Required |
Enter positive paper and screen luminances and a nonnegative maximum absolute natural-log ratio. Return ln(paper/screen) and a review boolean true when its absolute value is strictly greater than the caller limit. Equality is accepted; a negative ratio means paper is dimmer. This is not a WCAG contrast calculation.
lnRatio=ln(paperLuminance/screenLuminance); review=abs(lnRatio)>callerLimit Use the exact units, boundary rules, ordering and missing-evidence conventions above.
| Output field | Meaning | Value type |
|---|---|---|
| signedPaperScreenLogRatio | Signed Paper Screen Log Ratio; follow the units, sign, ordering and evidence convention stated above | number |
| callerContrastReview | Caller Contrast Review; follow the units, sign, ordering and evidence convention stated above | boolean |
{
"input": {
"observedPaperLuminance": 100,
"observedScreenLuminance": 200,
"callerMaxAbsoluteLogRatio": 1
},
"output": {
"signedPaperScreenLogRatio": -0.6931471805599453,
"callerContrastReview": false
}
}Limitations and assumptions
Its magnitude measures relative brightness under the supplied criterion rather than an accessibility contrast ratio. Interpretation depends on the units, sampling scope and exact model described above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.
Alternative or Complementary methods
Use Anthropometric Eye Height Seated Monitor Fit Checker for this related task: Eye and monitor-center heights determine a signed vertical viewing angle.
Use 20-20-20 Rule Compliance Interval Timer Helper when its separate inputs and assumptions fit the question: The 20-20-20 mnemonic links elapsed viewing time with a distant look and a short break.
References
Similar or alternative tools
- Anthropometric Eye Height Seated Monitor Fit Checker
Eye and monitor-center heights determine a signed vertical viewing angle.
- 20-20-20 Rule Compliance Interval Timer Helper
The 20-20-20 mnemonic links elapsed viewing time with a distant look and a short break.