One decision, one second cue, one controlled retest
Deuteranopia: Keep the Decision Outside the Color
Quick answer
A deuteranopia review should test whether the decision survives without its color.
Choose one real task, identify the status, series, region, or control whose meaning is carried by hue, and add a second cue such as text, shape, pattern, line style, or position. Retest the same source with the same simulation method and viewing size. Success means the reader can make the decision without naming a color.
Do this now: upload one representative screen, select Deutan with Brettel 1997, and write down the first question the screen no longer answers clearly; repair that answer before moving to another component.
Run the decision-first checkThe current results explain vision and methods, not the repair record
Colblindor’s deuteranopia article, opened in September 2026, describes the condition and several color-confusion areas. Pilestone’s color-vision-deficiency page, also opened in September 2026, gives another short description and examples of colors that may become similar.
DaltonLens’s simulator page, opened in September 2026, separates the simulation choices. It connects Brettel to its 1997 paper, Viénot to a 1999 simplification for protanopia and deuteranopia, and Machado to a 2009 model that addresses anomalous trichromacy.
Definitions, examples, and method notes help a reader choose a preview. They still leave a practical gap: a record that starts with the blocked decision, selects one repair, and repeats the task without changing the test conditions.
“Deutan” is the control; “deuteranopia” is the page target
The site uses Deutan for the simulator control and family label. This guide uses deuteranopia for the full dichromacy target. The merge-term searches “color blind deuteranopia” and “colour blind deuteranopia” belong here as alternate phrasing, not as separate pages.
A selected control is not a diagnosis. It produces a model-based preview for design inspection and cannot establish what one person sees.
The archived case: color named the class, so the class disappeared with the color
An Etre article dated May 20, 2006 used a Holmes Place gym timetable as its example. The timetable assigned red to conditioning classes, blue to cardiovascular classes, and yellow to holistic classes. The article showed separate views for normal color vision, protanopia, deuteranopia, and tritanopia.
In Etre’s 2006 account, the deuteranopia and tritanopia views made combat and conditioning classes particularly difficult to distinguish. The article also noted that a black-and-white printout caused trouble even for readers with normal color vision. That second observation matters: the design problem was not confined to a diagnostic label; the category had been entrusted to color.
Holmes Place’s remedy in that 2006 example was a written column that named the exercise category alongside the color coding. That was the client’s implementation described by Etre, not work performed by this site and not a feature inherited from the archived site.
What can—and cannot—be carried forward from the old example
| Source observation | Scope of the observation | Safe design lesson | Claim this page does not make |
|---|---|---|---|
| Class type was encoded with red, blue, and yellow | The Holmes Place timetable described by Etre in 2006 | Keep the category name outside the color channel | That those colors always fail in every interface |
| Combat and conditioning became hard to separate | Etre’s deuteranopia and tritanopia renderings of that timetable | Test the decision, not the color name | That every person sees the archived rendering |
| The monochrome printout was also difficult | The print case reported in the same 2006 article | Check the design with color unavailable | That grayscale is a deuteranopia simulation |
| A written category column supplied the same information | Holmes Place’s remedy reported by Etre in 2006 | Repeat meaning in text when the label fits | That text is the only valid second cue |
Decision-first component check
| Component | Question it must answer | Color-only warning | Second cue to test |
|---|---|---|---|
| Status | Is this ready, waiting, or blocked? | Only the fill changes | State word plus a distinct icon |
| Chart | Which series owns this point? | Lines differ only by hue | Direct label plus line style |
| Map | Which route or region applies? | Adjacent areas rely on color alone | Boundary, pattern, or route symbol |
| Form | Which field needs action? | Error appears only as a colored border | Linked error text plus an icon |
| Control | Which option is active? | Selection changes only in color | Marker, wording, or shape change |
Ask the question in the middle column before studying the simulated palette. A repair passes this check only when its second cue answers that question on its own.
Color-off preflight before the simulator
Duplicate the screen under review and temporarily remove the category colors while leaving labels, shapes, layout, and content unchanged. Try the same task in both copies. Record the first decision that fails in the color-off copy.
This preflight does not simulate deuteranopia. It isolates a simpler dependency: whether the task already requires color before any vision model is applied. Fix that dependency first, then use the Deutan preview to inspect the revised screen.
Controlled worked example: a release table
Begin with a release table whose Ready, Waiting, and Blocked rows differ only by fill color. Save the screen at its real viewing size. Run it with Deutan and Brettel 1997 while keeping the crop, source, and full-model setting fixed.
Add the state word inside every row. Give Waiting a clock-shaped marker and Blocked a stop-shaped marker, then rerun the same source dimensions and method. Hide or ignore the fills and identify each state from the words and markers alone.
This site-created example measures whether the revised table preserves its state labels under one controlled setup. It does not certify the product, diagnose a viewer, or claim that the simulation reproduces lived vision.
Repair decision table
| Observed result | What it supports | Next action | Controlled retest |
|---|---|---|---|
| The task fails in the color-off copy | The source depends on color before simulation | Add a second cue | Repeat with color still unavailable |
| The task fails only in the Deutan preview | The selected model exposed a collision in this setup | Strengthen the affected label, symbol, or boundary | Keep source, crop, size, and method fixed |
| Brettel 1997 and Viénot 1999 disagree | The finding is method-sensitive | Record the disagreement and repair the cue | Change only the method between runs |
| The task works from text, shape, pattern, or position | The decision has a second channel in this check | Test at the real viewing size | Keep the task wording unchanged |
Deuteranopia review worksheet
| Field | Record the observed setup |
|---|---|
| Screen and user task | ____________________________ |
| Decision the component must support | ____________________________ |
| Result with color unavailable | ____________________________ |
| Simulation method and source year | ____________________________ |
| Crop, size, and model setting | ____________________________ |
| Failure observed in the preview | ____________________________ |
| Second cue added | ____________________________ |
| Result after the controlled retest | ____________________________ |
Keep the before and after captures with the worksheet. A different crop, size, method, or task starts a new record rather than extending the old one.
A route decision should not depend on green versus red
The place I most want readers to stop relying on red and green is the traffic layer on a navigation map. It uses green for clear roads and red for congestion, but people with different color vision may see two similar patches and be unable to tell quickly which road is open and which one to avoid. This matters to me because people often check a map when they are short on time or need to make a quick decision; if the colors blur together, they may take the wrong road, make a longer detour, or miss congestion ahead. Writing “clear” or “congested” and adding different patterns, line styles, or icons lets people make that decision without guessing from color.
Sources and limits
The competitor pages were found through Google US natural results and opened in the signed-in Chrome profile on September 24, 2026. Colblindor and Pilestone support the terminology and color-confusion context. DaltonLens documents the cited 1997, 1999, and 2009 method scope.
The archived Etre HTML snapshot and its accompanying source notes were checked directly for this rewrite. They support the May 20, 2006 timetable example, the class-color mapping, the four comparison views, the combat-versus-conditioning finding, the monochrome-print observation, and the written-category remedy. Only substantive article facts are carried forward; comments, navigation, subscription controls, and footer material are excluded.
The historical case remains Etre’s report of Holmes Place’s design and remedy. The decision-first checklist, color-off preflight, worked example, decision table, and worksheet are new review tools created for this site. They do not imply that this site built, inherited, or tested the archived timetable.