PowerPoint Pixelation Repair

I have a PowerPoint presentation that is experiencing pixelation issues when converted to PDF. The image placement is perfect, but the final PDF shows the images as blurry. There are four images that need to be fixed. I have the original high-resolution images for each.

Ideal skills and experience:
- Proficient in Microsoft PowerPoint
- Strong understanding of image resolution and pixelation issues
- Experience with PDF conversion from PowerPoint
- Attention to detail to ensure image placement remains unchanged