From the course: Photoshop for Teaching and Learning

Presentation resolutions and load times

From the course: Photoshop for Teaching and Learning

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Presentation resolutions and load times

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- [Instructor] In this chapter, we're going to focus on preparing images with Photoshop for use in presentations. To kick that off, we need to take a minute and talk about presentation file resolutions and load times. Now, the type of presentations that we're going to focus our attention on are simply the most common types of live presentations, which are those that would be delivered as slides on a projector, or via a live streaming webinar using PowerPoint, Keynote, or perhaps a web-based tool, such as Google Slides or Prezi. Now, there are lots of other ways you can present, but since these are the most common in teaching and learning, that's what we're going to focus on. Now, it doesn't matter if you have a high resolution or a retina display screen for you Mac or Windows computer. The presentation tool that you choose is going to automatically send your presentation out to your projector at a fairly standard resolution. Now, PowerPoint, for instance, defaults all new slides to a size of 13.333 inches by 7.5 inches, at 96 dots per inch, or 33.87 by 19.05 centimeters at 37.795 pixels per centimeter. Which seems like an incredibly odd size for a slide destined for a digital display. Well, when you do the math, it turns out this is simply an image that's 1280 by 720 pixels, or 720p. Now, Keynote doubles that to default to 1920 by 1080 pixels or 1080p. There are exceptions to this, but as a general rule, that's really what your final presentation is going to be delivered in - 720p for PowerPoint, or 1080p for Keynote. Webinars are often streamed out at these same resolutions to save on bandwidth. Now that means that, though you may be able to grab pictures with your smartphone at roughly 12 megapixels, or 4032 by 3024 pixels, or significantly higher with other digital cameras, your final presentation is going to be automatically crunched down to a significantly lower resolution when you go to present it. So my question to you is, would you rather let your presentation tool of choice handle that image compression for you, or would you like to be in control of how your image will be compressed and ultimately look? Now, it certainly is easy to simply toss that high resolution image into your presentation, but doing so puts a few things against you. First is file size. Drag a 12, 24, or 36 megapixel, or even higher, image into your presentation tool, and each image may bloat your presentation's file size by anywhere from a few megabytes to dozens, or more, for each image. Now these larger images can add significant size to your overall presentation file. If you're someone who includes lots of images, ending up with a presentation that reaches into the hundreds of megabytes is certainly possible, and it's not necessary. For your desktop or laptop, it may be not so much of an issue, but remember, in classrooms and conference venues, the presentation computer is often not the fastest machine, with the most amount of RAM stuffed into it that you're going to find. As you're presenting, each of those images will be being compressed and rendered on the fly, as they're loaded into memory and rendered on the screen. Now, you can use the reduce file size option that's included in many of these tools, but it's an often overlooked feature, and it still puts the compression decisions of your images in the hands of a presentation tool, not a program designed specifically for image manipulation, like Photoshop is. Now, the solution to this is easy. Prepare your images in Photoshop and control the resolution and compression of your images yourself. Now, this will make your overall presentation file significantly smaller, load faster, and look way better.

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