SSRS can't properly render *some* images within PDF

I have a report that renders images (jpg) that have been collected from various sources. This works fine within the report viewer, and when exporting via Excel.

However, when exporting to PDF, about 5% of the images are rendered incorrectly as can be seen below, with the original on the left, and what is rendered on the right;

I find that if I open up one of these images in mspaint, and just click save, on the next report-run the image is now rendered correctly.

Are there any rules as to what image properties/format are valid for SSRS to render the image correctly within a PDF? Essentially I'd like to somehow find these images that will render incorrectly before the report is run and fix them prior...

This is an issue reported to Microsoft Connect.
From SSRS 2008 How to get the best image quality possible?:

The image behavior you see in PDF is a result of some image conversions that the PDF renderer does, based on how the PDF specification requires that serialize images into PDF.

We know it's not ideal, and we classify the loss of image quality as a product issue. Therefore, it's difficult to really say what to do to get the best quality image.

Anecdotally, I have heard that customers have good results when the original image is a BMP