What Is the Difference Between Aspect Ratio and Resolution?
To a newcomer, a discussion concerning aspect ratio vs. resolution looks like a whole lot of numbers. 1.33:1? 1.56:1, with a 2.55:1 thrown in for good measure?
What exactly does all of this even mean? Read on to toe the line with the best of them.
Aspect Ration vs. Resolution: What’s the Difference?
These two concepts are often confused with one another because they both refer to the dimensions of the frame. The resolution of a clip describes the area contained within its bounds in terms of pixels.
Footage that is 1920 pixels wide and 1080 pixels high is expressed as a resolution of 1920×1080. The aspect ratio is derived from this value. What’s the ratio between 1920 and 1080? 16:9, likely a familiar pair of numbers to media aficionados.
Other common video resolutions include:
- 640×480 (also known as Standard Definition)
- 1280×720 (commonly referred to as "720p")
- 1440×900 (technically named WXGA+)
- 2048×1152 (also known as 2K)
- 3840×2160 (commonly referred to as 4K)
Common aspect ratios:
- 4:3: This is the original NTSC/PAL standard.
- 16:9: Widescreen HD video, such as 1080×1920 or 1280×720.
- 8:5: This category includes most modern computer displays.
Frame vs. Pixel Aspect Ratio
Frame aspect ratio is synonymous with aspect ratio, plain and simple.
If the aspect ratio of a Premiere sequence is 4:3, for example, and you drag a clip that is 16:9 into the timeline, the clip itself will be fine, albeit slightly mismatched. It may be scaled smaller and letterboxed, or you could crop in so that the clip fills the entire screen. Cropping in paves the way for panning, scanning, and other tools you can use to make your project pop.
Pixel aspect ratio is a slightly different matter. Frame aspect ratio takes the entire frame into account, but pixel aspect ratio takes things one step further: the pixels themselves are our objects of scrutiny here.
Related: How to Resize an Image on Any Device
Square Pixels and Pixel Aspect Ratio
Those who use Photoshop or any type of video editing program have probably come across the term “square pixels” once or twice. Shouldn’t ALL pixels be square, though?
In a perfect world, you would be correct. However, just because something should be so doesn’t mean it always is. According to Adobe, this discrepancy occurs when an editing program’s standard for one aspect ratio or another differs from the standard that the source footage adheres to in terms of how many pixels each frame should contain.
An example: 4:3 footage shot under the DV NTSC convention will be 720×480 pixels wide and tall, respectively. In some programs, however, the standard varies—640×480, for example. When worlds collide, something’s got to give.
Programs like Premiere make the adjustment by squeezing or stretching the image. Consequently, the original configuration of “pixels” stretches too. The ratio between the size of the original pixels and the number of newly-generated real pixels that the original image now occupies comes together to generate the eventual pixel aspect ratio of the image.
In a sense, most original, native footage can be considered in terms of square pixels; this conversion takes place only when you bring footage of this nature into the editing program. When NTSC footage undergoes this process, nothing changes about the height. However, its 720 pixels of length now has only 640 pixels of real estate to fit into. In stark contrast to our original array of perfect squares, the original pixels are now narrower than they once were.
Anybody who has ever struggled with a distorted image or video clip will be glad to know that, when this happens, the clip’s pixel aspect ratio will usually be the culprit. Bridging the gap and adjusting your footage accordingly will usually be a quick and effective fix.
Related: How to Reduce the Size of a JPEG
If It Doesn’t Look Right, It Probably Isn’t Right
Following your natural sense of intuition may lead you down a rabbit hole or two, but there will usually be a valuable lesson that you can pick up along the way. Sure, scaling the footage’s height or width manually may yield an approximation of victory, but at what cost?
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August 7, 2021 at 09:30AM