Exporting PDF to PNG changes color saturation

Quote: "Once I use the Export PDF tool..."

What software program are you exporting the PDF from?

Your screen capture looks like the Export To / Image dialogue box, where you are exporting FROM a PDF, not making a PDF.

It's confusing: can you give us more details?

• What are you trying to do?
• In what software program?
• How were the graphics created? (ie, which software programs created them)
• Were they color managed? (ie, with embedded color profiles)
• How were they saved into the current file format?

In your graphic, the left side is the original with brighter colors, and the right is the converted version, correct? The converted version looks like the graphic's colors were converted to CMYK somewhere in the workflow.

There are a lot of factors that control color. Some are:

1. How were the original graphics created? Were they color managed (such as embed color profile)? Were the colors accurate then?
2. What file format were they? TIF, GIF, PSD, PNG all handle color differently. Depending upon the settings in the "save" dialogue box, you'll get different color.
3. How were they built into a PDF? For example, were they placed into Word and then exported to PDF from Word? If so, what were the conversion settings that made the PDF?
4. Did someone "adjust" the graphics in Photoshop or another graphics program?

As @Abambo said, resolution doesn't affect color at all, but it does affect the overall appearance of the graphic. Today, we recommend 400 dpi/ppi for all graphics, even those for digital, given that the majority of mobile devices and desktop monitors are 400 ppi and higher.