Pixel with 1:1 aspect ratio — standard in digital cinema and modern displays. Legacy DV and SD used rectangular pixels, causing distortion in aspect conversion.
Square Pixel
On set, you'll notice the difference between square and rectangular pixels primarily when working with older SD cameras or DV material and transferring it to modern displays. A square pixel has an aspect ratio of 1:1 — width and height are identical. This might sound trivial, but it's fundamental to all digital image processing. Modern digital cinema cameras, DSLRs, and virtually all contemporary monitors exclusively use square pixels. This is the industry-standard that has been agreed upon.
It was different with classic PAL DV or SD video. These formats used rectangular pixels — typically with an aspect ratio of about 4:3 on the sensor, even though the final image output was 16:9. This led to distortion: a circle you saw during recording would become an ellipse when played back later. During editing, you had to manually correct the Pixel Aspect Ratio (PAR) — in your NLE under the sequence settings. Many old editing suites had special monitors that compensated for this distortion, so editors saw the material without distortion.
In practice today: When digitizing DV material or old HDV, you must set the Pixel Aspect Ratio correctly during ingest — usually 1.5:1 for PAL or 1.2:1 for NTSC — otherwise, everything will look distorted. Modern formats like ProRes, DNxHR, or native 4K/UHD consistently use square pixels. This significantly simplifies the entire post-production workflow. You no longer need to make corrections; graphics and titles render correctly directly, without distortion artifacts. Even during color grading, you don't have to keep pixel distortion in mind — you see the image exactly as it will be output.
Important: Square pixels are not the same as the final image aspect ratio (e.g., 16:9 or 2.35:1). The aspect ratio describes the geometry of the entire frame. Square pixels simply mean that each individual pixel is square itself. If you create a 1920x1080 timeline, you have 1920x1080 square pixels — and the output is a 16:9 image. Clean, no surprises.