How to Use Accessible Symbols and Colors in PDF Tables
Question details
The user wants to ensure that plus and minus values in PDF tables are correctly interpreted by screen readers while retaining red and green visual indicators.
- Product
- Device & OS
- not provided
- Scenario
- Optimizing a PDF document containing numerical data tables for visually impaired users and screen-reader compatibility.
- Observed behavior
- Standard keyboard hyphens used as negative signs are often treated as silent characters and skipped by screen readers, and relying solely on color fails accessibility standards.
Ensure you have access to a PDF editor or your original authoring software (like Word or InDesign) to modify text symbols and review color settings.
Replace Keyboard Hyphens with Unicode Minus Signs
Swap standard hyphens for the true Unicode minus symbol to ensure screen readers announce negative numbers correctly.
Most screen readers treat standard keyboard hyphens as silent punctuation marks. If you use a hyphen (the key next to zero) for a negative number, the screen reader will likely skip it entirely, causing confusion. Replacing it with the true Unicode minus sign (U+2212) resolves this issue.
Open your PDF or the source file in your authoring software (e.g., InDesign, Word, or a PDF editor).
Navigate to the Insert tab and click on 'Symbol' or open the 'Glyphs' panel in your application.
Search for the character code U+2212 to find the universal Unicode minus symbol.
Use the Find/Change (or Find and Replace) tool to globally replace the short keyboard hyphens in front of your numbers with the new Unicode minus sign.
Optimize Color Usage for Accessibility
Ensure that red and green colors are used correctly as visual aids without being the sole conveyer of information.
Enhance PDF Accessibility with WPS Office
WPS Office provides comprehensive PDF editing tools that allow you to quickly find and replace silent hyphens with proper Unicode minus signs, adjust text colors for better contrast, and ensure your tables are professional and accessible.
- 1. Open your PDF: Launch WPS Office and open your PDF document containing the data tables.
- 2. Enter Edit Mode: Navigate to the 'Edit' tab on the top ribbon and select 'Edit Text'.
- 3. Insert the proper symbol: Highlight the incorrect hyphens, delete them, and paste or insert the Unicode minus sign (U+2212).
- 4. Save the document: Once all accessibility changes are made, click 'Save' to apply your edits to the PDF.
Frequently Asked Questions
Why doesn't the screen reader read my negative numbers in the PDF?
Screen readers often treat standard keyboard hyphens as silent punctuation marks. To ensure a negative value is read aloud as 'minus', you must use the official Unicode minus sign (U+2212) instead of a regular hyphen.
Can I use red and green colors to indicate positive and negative values?
Yes, but you should not rely exclusively on color. You must include a textual indicator (like the minus sign) or structural tag so that color-blind users or screen readers can understand the data. Additionally, ensure the colors have sufficient contrast against the background.
How do I type a Unicode minus sign (U+2212)?
You can insert it using the 'Symbol' or 'Glyphs' panel in your authoring software (such as Word or InDesign) by searching for the character code 2212. Alternatively, you can copy the symbol from a character map and paste it into your document.
