Final answer:
To reduce file sizes of images in a presentation, it's effective to optimize and compress images in bulk using image editing software that handles batch processing.
Step-by-step explanation:
To reduce file size for all scaled images in a presentation, you can optimize all images in bulk. This is usually the most efficient method and can be done with image editing software that supports batch processing. By reducing the resolution of images to match the intended display medium (screen or print) and applying compression, you can significantly decrease file sizes without manually editing each photo. For digital cameras, the resolution and compression settings directly influence the size and quality of the photos taken. To maintain the best quality, use no compression when shooting, and then compress later if necessary. For presentations, moderating these settings can provide an optimal balance of quality and file size.