Documentation
Reading a report
A report lists each text region TIA found in your image, the contrast it measured, what WCAG asks for, and a verdict. This page explains each part.
Pass, Fail, and Review
- Pass
- The text met the WCAG contrast requirement for the level you chose, within the limits of this beta.
- Fail
- The measured contrast is below the requirement. If the text looks clearly readable, especially a bold heading, check it by hand before you change it: TIA can read strong bold text too low.
- Review
- TIA could not confirm a pass or a fail. Treat the region as unchecked and check it by hand. Review is never a hidden Pass.
The headline at the top of the report sums these up. If TIA found no text at all, the report says so, and that is not a Pass: if the image has text, check it by hand.
Ratios
Contrast is a ratio from 1:1 (no difference, like white on white) to 21:1 (black on white). Each region shows two numbers:
- Ratio: the contrast TIA measured between the text and its background, to one decimal place. “Not measurable” means TIA could not get a number.
- Needs: the ratio WCAG asks for at your level and the text’s size.
| Level | Normal text | Large text |
|---|---|---|
| AA (the usual target) | 4.5:1 | 3:1 |
| AAA (stricter) | 7:1 | 4.5:1 |
Text size
WCAG counts text as large from 24 px, or from about 18.7 px when it is bold. Large text needs a lower ratio. An image does not say how big it will be shown, so TIA estimates the size from the image. A high-resolution screenshot makes text look bigger than it is, so check results on small text at the size people will see it. The size is under Text size and low-vision reading in each region.
Low-vision reading
Also under Text size and low-vision reading: an extra estimate of how easily people with different eyesight could read the text. It goes beyond WCAG and does not change the verdict.
| Reader | Meaning |
|---|---|
| 20/20 | Typical eyesight |
| 20/40 | Mild low vision |
| 20/80 | Moderate low vision |
| 20/200 | Severe low vision |
Each reader gets comfortable, difficult, or unreadable. “Not measurable” means TIA could not estimate it for that region.
The numbered image
Your image is shown with a numbered outline around each text region. The outlines only show where each region is; they all look the same whatever the verdict. Find a region’s verdict by its number in the findings list.
The downloaded JSON
Download report (JSON) saves contrast-report.json. It is the same JSON the HTTP API returns, so a script can read a report you made by hand. Region ids start at 0, so region 1 on screen is id 0 in the file.
The example on the home page
Before you check anything, the home page shows one banner in two color choices, with a ratio beside each. Those ratios come from the colors each banner was drawn with, not from TIA. Both banners are in the samples. Checked there, TIA fails the pale banner at AA and AAA and passes the dark banner at AA. At AAA it passes two of the dark banner’s four lines and marks the other two Review. It also measures lower ratios (as low as 4.9:1 on the dark banner’s button), so its numbers will not match the example’s.