By Ron Dawson
Photographers often ask me what resolution setting to use when they prepare photos to be displayed along with video in a fusion presentation.
The simplest way to think about this is to understand the pixel ratio of video relative to a photo.
Canon’s 5D Mark III is a 22.3-megapixel camera. A full-sized image from this camera is 5,784 pixels wide and 3,861 pixels tall. Now compare that to a full-sized 1080p high definition frame: 1,920 x 1,080 pixels. The photo is just over 3 times the width and height of an HD video image. If you’re shooting at 60 frames per second on this camera (in order to achieve “pure” slow motion), then the video resolution drops down to 1,280 x 720 pixels. Now that same photo is just over 4.5 times the size of the image.
Why is all of this important? Because knowing this information will help you determine the pixel size and dimension of images you plan to use in a video. I’ll get to that answer in shortly. First, we need to consider aspect ratio.
Aspect ratio is simply the ratio of your horizontal length to the vertical. HD video has a 16:9 aspect ratio (also written 16x9 and verbally expressed as “16 by 9”).
1,920 / 1,080 = 16 / 9 = 1.7778
Most photos have completely differentaspect ratios. For example, 4x5 and 8x10 images come out to a 0.8 ratio. The aforementioned 22.3-megapixel image has a 1.49 ratio. So, when you export an image and maintain its aspect ratio, you know from the start that when you drop it into a video, it will not fit nice and neat.
But, depending on the project, fitting nice and neat is often not necessary. So this is where we get to the nitty-gritty.
When exporting photos for video from Adobe Photoshop Lightroom, you should determine ahead of time how you plan to incorporate the photo. If it will be a static image (no movement or growth), just export it constraining the ratio to 16x9 and selecting the width to match pixel width of the video, either 1,920 or 1,280 pixels wide. This will result in the image being cropped. If you don’t want that to happen, then you must settle on having black space on either side of you image in the video.
In a Photoshop workflow, use the Crop tool's aspect ratio drop down menu to select your ratio (or create a custom one). In the fields next to it you can set a specific pixel size by entering the number followed by px. Use File > Save for Web to minimize the file size while keeping the onscreen quality high. Assign a new file name to avoid overwriting your original.
Here’s a video I produced for Canadian wedding photographer Gabe McClintock. Gabe specifically asked that I not put any movement on his photos. As much as possible he wanted to preserve their original look, minimizing any cropping. So where the aspect ratio didn’t allow for insignificant cropping, I added a white background to match his website so that the image presentation would appear seamless with no borders.
If you plan to do any movement of the photo, Ken Burns-style, then you will want a photo that is larger than your HD video so that you zoom in on it without losing quality. The question is, how much bigger. There is no single answer to this. It all depends on how much you want to “zoom” into the photo. But keep this in mind: the bigger the photo, the more taxing on your computer it will be. Try importing twenty photos 4,000 pixels or wider into a video project and start adjusting the size. Unless you have a super-fast, ultra-powerful computer, it will be sluggish.
This video I did for Yosemite photographer Shawn Reeder did include the zooming in and zooming out I traditionally do with photos. In these cases, I used photos significantly large enough to zoom in and out without losing quality.
I will typically export JPEG images and aim for a photo size that is in the neighborhood of 2,500 pixels on the wide side. These photos come in around 880k to just under 2MB in file size. Whenever a client gives me photos for a video and I see they are all 5MB are larger, I know right away they’re going to be way too big and I’ll need to shrink them all down to a more manageable size.
I should note at this point that dots per inch (dpi) does not matter when exporting. Meaning: you don’t need to worry if your photo is 300 dpi or 72 dpi. It's a setting that's only relevant to printing. All you need to know is the horizontal and vertical width in pixels. An 8x10 image at 72 dpi is only 576 x 720 pixels. Too small for HD video. However, a 4x5 photo at 600 dpi is 2,400 x 3,000 pixels. That’s larger than HD.
That’s basically it. Know your pixel dimensions and intended use, and aim for a size that won’t be too taxing on your system.