What is the best file format for importing scans or digital camera images?
JPEG is fine for most presentation requirements, provided that the compression is not to high when the JPEG file is made.
If your images are large and paint up slowly on the screen try saving them as PNG files, they should then paint up quicker than JPEG files, but the overall size of your PowerPoint presentation file may be larger.
You should ensure that all bitmap images (i.e. scans etc.) are saved as RGB format files, rather than CYMK. This simply means that the colour information in your image is made up from RED, GREEN and BLUE (RGB) rather than CYAN, MAGENTA, YELLOW and BLACK (CYMK). Computer screens and projectors all build up images using RGB, however colour printers tend to use CYMK to reproduce colour images.

