March 18, 2020, add version for macOS 64-bit.
This software provides a pass/fail assessment against WCAG 2.0 (JIS X 8341-3:2010) color contrast success criteria.
It supports the drag-and-drop (*) image file to window or get colors from picture of Clipboard (Colors that has been acquired are may not be accurate).
* You can drag and drop directly from the web browser in macOS. In the Windows version, Mozilla Firefox only supports drag-and-drop from the web browser.
See contrast ratio - Web Content Accessibility Guidelines (WCAG) 2.0.
- contrast ratio
(L1 + 0.05) / (L2 + 0.05), where
- L1 is the relative luminance of the lighter of the colors, and
- L2 is the relative luminance of the darker of the colors.
Note 1:Contrast ratios can range from 1 to 21 (commonly written 1:1 to 21:1).
Note 2:Because authors do not have control over user settings as to how text is rendered (for example font smoothing or anti-aliasing), the contrast ratio for text can be evaluated with anti-aliasing turned off.
Note 3:For the purpose of Success Criteria 1.4.3 and 1.4.6, contrast is measured with respect to the specified background over which the text is rendered in normal usage. If no background color is specified, then white is assumed.
Note 4:Background color is the specified color of content over which the text is to be rendered in normal usage. It is a failure if no background color is specified when the text color is specified, because the user's default background color is unknown and cannot be evaluated for sufficient contrast. For the same reason, it is a failure if no text color is specified when a background color is specified.
Note 5:When there is a border around the letter, the border can add contrast and would be used in calculating the contrast between the letter and its background. A narrow border around the letter would be used as the letter. A wide border around the letter that fills in the inner details of the letters acts as a halo and would be considered background.
Note 6:WCAG conformance should be evaluated for color pairs specified in the content that an author would expect to appear adjacent in typical presentation. Authors need not consider unusual presentations, such as color changes made by the user agent, except where caused by authors' code.
A legally binding promise of certain qualities is not given. Alfasado is not responsible for damage. Alfasado accepts no responsibility of any kind for indirect, accompanying or subsequent damage.
Alfasado reserves the right to change or improve the software without notice or to replace it by a new development. Alfasado is not obliged to inform the buyer of changes.