If a PDF doesn’t look as you expected in Preview on Mac
If the text or line art in a PDF opened in Preview doesn’t look right, try changing the “Smooth text and line art” option in Preview preferences. This option smooths out large characters and line art so they don’t appear as jagged. However, small text may look blurry, some line art may not be visible, and Preview may take longer to display your document.
In the Preview app on your Mac, choose Preview > Preferences, then click PDF.
Select “Smooth text and line art.”