After watching the recently released Google Pixel Phone Advertisement on YouTube, I thought to give this animation a try by making a Photo Slideshow Animation in PowerPoint. If you download the presentation from the link below and play the slideshow without placing any pictures on the slides then you can notice that we are just moving through 229 slides where each slide has been shown on the screen for a specific duration of time.
You can learn more about the calculations by downloading the Excel Worksheet from the link below. We just placed different-sized subtracted rectangles on every slide where each slide having a picture in the background of these shapes. Then we adjusted the Slide Transition timings and when you play the slideshow then all 229 slides are shown in a very short duration of time.