PDF/UA Rendering Turns Images and Boxes Gray

Updated:June 9, 2026

When converting a PDF to PDF/UA format using ConvertToPdfUA() or SaveAsPdfUA(), images, SVGs, shadows, and box elements appear with gray shading in the output.

Chromium has a paint order issue in PDF/UA mode that causes certain elements to composite incorrectly. The gray appearance is a rendering artifact produced by how the browser stacks and paints layered elements when PDF/UA mode is active.

Solution

Add -webkit-filter: blur(0) to the HTML element. This forces Chromium to create a new compositing layer, which triggers hardware acceleration and causes the browser to re-evaluate element stacking order, eliminating the gray artifact.

Inline:

<html style="-webkit-filter: blur(0);">

<html style="-webkit-filter: blur(0);">

HTML

Via CSS:

html {
    -webkit-filter: blur(0);
}

Apply the filter to the smallest element that resolves the issue rather than to the <html> element. Applying it at a large scope may slightly affect performance on low-end devices due to forced hardware acceleration, and in some layouts it can affect z-index stacking. Adjust z-index values as needed if stacking order changes after applying this fix.

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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