I am stuck on how to re size images for a powerpoint presentation. I am an artist and just scanned a large number of images at 300 dpi but was told that this is too large for creating a ppt presentation and that I should reduce images to 75 dpi. When I do that, each image gets very small, will that still project alright? Do I need to find a proper scale or size and be consistent? I think I am confused. I tried just finding information on image size vs. canvas size but this didn't help me for my particular case. Help would be so appreciated!. -LearningCurve
It's true that high-resolution images will only serve to bloat the PowerPoint file. Images destined for PowerPoint are best saved using Save For Web to JPEG, (or PNG if preservation of transparency is desired).
Ideally, you'd want the images saved at the size, (dimensions), they'll appear on the final slide layout. You may know or be able to ballpark those sizes if you're the one who'll do the slide layouts. But if you're only handing the images off to someone else, just consider that the typical PowerPoint slide is a letter-size page in landscape orientation, so that's the largest size they could need, and most times, they won't be covering an entire slide with the image. The monitor or projector on which the slide will be displayed most likely will be 800-1200 pixels in width.
I don't know what size, (dimensions), the 300ppi scans are, but in your position, I'd simply resize each image using Photoshop's Image Size dialog. With "Constrain Proportions" and "Resample Image" both enabled, enter a value in the Pixel Dimensions | Width field of 1000-1200 pixels, (more than enough), click OK, and then Save For Web as mentioned above. Don't worry about resolution, (ppi). Save For Web discards that information. Pixel dimension is the only critical measurement.
All of the vim with none of that annoying vigor.