When viewing PDF files, they may not be displayed properly, such as low-quality images or blurry text.
Cause
The error may be caused by one of the following.
You are using “OS X El Capitan” as your operating environment (with this OS, PDF files may not be displayed properly even under the recommended operating environment.)
You are using a system other than the recommended operating environment
Solution
■ For 1.
PDF files are displayed properly in macOS Sierra and macOS High Sierra, so please upgrade to the latest version.
■ For 2.
See here and check that you are using the recommended operating environment.
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