Background
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I want to decrease size of the .pdf filled with images.
In `Preview` in can be dome through `Export` and set `Quartz Filter-> Reduce File Size` before saving.

[![Preview-Export](https://i.stack.imgur.com/dzzVm.png)](https://i.stack.imgur.com/dzzVm.png)

Problem
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The file indeed decreased from ~30MB to 0.37MB. 

But the result has such poor quality that images are barely readable.

Question
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I saw an examples of using `Image Magic` to achieve that - but can it be done by **Preview** without any external software?