Set Content Color: Automatically Fix Low-Contrast Text in PDF

Low color contrast is one of the most common reasons PDFs fail accessibility audits, making documents difficult or impossible to read for users with visual impairments. Light-colored text on a white background or low-contrast graphics can prevent compliance with WCAG and PDF/UA standards. With the new Set Content Color action in PDFix Desktop, you can automatically adjust text, shapes, and graphic elements to meet required contrast ratios – helping you pass audits, improve accessibility, and create an inclusive reading experience without manually editing each element.

This action allows you to change the color of selected content objects — such as text, paths, or any other graphical objects — by specifying a new fill and/or stroke color. You can target:

• All objects, or
• Only objects with specific properties, using a template condition

The goal is to easily fix contrast issues without manually editing content in a PDF editor. This is ideal for batch-remediation workflows – like converting all red text to black across thousands of documents.

Review all configurable parameters to understand which ones can be adjusted for your use case

Suppose your document contains red lines and red text (fill_color and stroke_color of 255,0,0), and you want to convert them to black RGB(0,0,0). Here’s how you define the filter:

"template": {
    "object_update": [
    {
        "query": {
        "$and": [
            {
            "$0_fill_color": [
                "255",
                "0",
                "0"
            ]
            },
            {
            "$0_stroke_color": [
                "255",
                "0",
                "0"
            ]
            }
        ],
        "param": [
            "pds_object"
        ]
        },
        "statement": "$if"
    }
  ]
}

This action will update all red-colored objects to black, making them more accessible on light backgrounds.

Follow these best practices to improve PDF accessibility, ensure WCAG compliance, and streamline remediation using PDFix:

• Automatically correct color contrast using the Set Content Color action to ensure all content meets accessibility standards in the final PDF output
• Use the object_update template to selectively target only those objects (text, shapes, lines) that fail contrast or violate visual accessibility rules
• Validate color combinations to meet WCAG contrast guidelines for users with low vision or color blindness

The Set Content Color action is part of the Content category in PDFix Desktop. It enables users to automatically fix low color contrast issues in PDF documents – an essential step for meeting PDF/UA and WCAG accessibility standards.

Ideal for batch processing, this action helps organizations remediate large volumes of PDFs by applying consistent fill and stroke color corrections based on customizable filters. It eliminates manual editing, improves readability, and ensures accessibility compliance at scale.

Need help setting up color filters with PDFix templates? Reach out – our accessibility experts are ready to assist.