When it comes to video graphics, a lot of folks get confused in the area of resolution. You'll hear the term PPI or DPI thrown out there. DPI is, "Dots Per Inch" and that's really a printing term. PPI is, "Pixels Per Inch" and that's much more relevant when discussing computer graphics. However, in terms of video, none of it is relevant. You see, the same size video graphic can be displayed on multiple sizes of screens. So, I could take that 720p graphic or video file and put it on a television set that's huge in my living room.
Put it on an iPad and look at it on that screen. Shrink it down to a mobile phone on the Android operating system or even play it back in a movie theater. You see, it's the same number of pixels. When dealing with video, you have fixed resolution formats. Meaning that, we measure them in total pixel count. Let's take a look at some files and see how this really comes to life. In this particular image here, I have a lot of pixels to work with, more than I need for a video file. If choose Image, Image size, I could see the pixel count and it's right now 1343x895.
Now, that's too low for use in 1080p, but more than enough, for using the 720p HD format and plenty for standard definition work flows as well. Let's zoom in here. This particular image is a Mosaic, meaning that small tiles make a larger image. If you look closely there, you could see a sort of the silhouette of a dog as well as a busy field. Let's start to zoom in and you notice here, that's a 100% and as we keep going in, the image will start to be pixelate.
That's because these individual areas are really squares of light. The white lines show you the border on each pixel. Now, I could bring up the Navigator Panel and this makes it easier to see the whole image and notice by dragging, I could zoom in or out and use this red box to move around the image. Each square is one pixel value. If you take the Eyedropper tool and you click, you'll see that the colors update over in the color mixer, so you can actually see what that square is doing.
However, when put together, those individual pixels comprise an image and as you zoom out, it starts to take shape. This is a pretty straightforward concept, but what I'd like to show you is how it works with the same image sized for different workflows. Let's switch over to Adobe Bridge and I have the same image prepped for both standard definition and HD. You'll notice here that we have the 720p version. Let's adjust this here, 1280x720, here's the HD1 1920x1080, the two common HD sizes and then we have the standard definition, in this case, 720x480 and 720x480.
However, they display differently. This is because of pixel aspect ratio, which is a topic, we'll explore more in an upcoming movie. But essentially, it means that pixels are not square or a one-to-one ratio. Therefore, the numbers may not actually represent how the image displays. While both of these images are 720x480, they will display in size differently on the screen. Let's go ahead and open these up and I'll press CTRL+R for the rulers and right-click and switch to pixels.
So, this one is 720x480 and this one is also 720x480. However, one is a 4x3 aspect ratio and the other is 16x9. Both of these graphics could work in a DVD slideshow. The 16x9 aspect ratio is more commonly used these days, even when dealing with standard definition video for a DVD. For the 1080 graphic, you'll notice here that it's 1920x1080 and the 720 graphic is 1280x720.
You can always check this by going Image, Image Size and it will bring up the dialog box. What I want you to realize is that resolution does not matter. So, if I uncheck the Resample Image box and I change the Resolution per inch. Let's say to 200. You'll notice that the print size would change, but the total pixel dimensions has not changed, meaning that the file still has the same display size. So, changing the resolution field, that describes the pixels per inch, will have no impact on the video because video graphics are measured in total pixels.
Again, 1920x1080, for the HD version here, changing the resolution has no impact on the width or height, when we uncheck "resample image". Clicking OK, you'll notice that the document does not change sizes. A nice shortcut is to Alt or Option click down here, and you can quickly check the specs for a file, seeing the width and height, as well as the channel information, which we'll talk about in the second and the resolution setting, which can be ignored for video graphics.
This course was created and produced by Rich Harrington. lynda.com is honored to host this content in our library.
- Understanding still image concepts such as resolution and bit depth
- Matching your sequence settings
- Using Content-Aware Scale
- Working with raster and vector images
- Setting transparency
- Adjusting blend modes
- Animating with keyframes
- Creating custom gradients
- Performing automatic lens correction
- Using actions to speed up video workflows
- Correcting color
- Creating a depth matte with gradients
- Integrating Photoshop with Premiere Pro and After Effects