After uploading a PDF content, if the Web Viewer HTML5 rendering has lost some image quality -- images appear slightly distorted or grainy when compared to the original content source file -- then you might be able to resolve the issue by optimizing the source PDF file and uploading that newly optimized file to replace the original content record. You can try this by using the built-in optimization tool in Adobe Acrobat and by referring to the following sample optimization images and their recommended settings.

If you use Adobe InDesign, then please also review our suggested PDF Export Settings.

If you find that Acrobat's optimization didn't help resolve the distorted images, then please reach out to us at support@vitrium.com and provide us the details of the issue.