Your dog & TV. What happens when their flicker rate is faster than the TV frame rate?

This is probably in the ‘Things you didn’t know you didn’t know’ about your dog, category.

Firstly to understand why TV, and digital TV now, have the specifications that they do, we need to know about the dark ages of  analog filming AND TV. That is, Black and White, and the original Analog colour versions of screens.

Because there were technical limitations of analog cameras at the time, much of the film used for movies was filmed at ‘6-18 frames per second (fps), then projected closer to 20-24 fps. “  Modern day cameras still work at filming at 24 frames per second.

For various reasons, America, and half of the world ended up having a 60 Hz power system. Or 60 cycles of sign wave voltage cycles per second at the power-point. Australia and the other half went with a 50 Hz power system.

It was decided that the most suitable (to reduce power distortion effects on tv screens) would be to have TV frame rates in integer divisions of the power frequency. But since film was only created at 24 fps, they massaged the film into 25 fps in Australia, and 30 fps in America, Then used an INTERLACED pattern where odd rows on the TV were shown at 25 fps, then even rows at 25 fps.  (Analog tv’s used ray tracking left to right on the screen rather than displaying a whole row at once so there are many other complications going on here).

So to recap 50 Hz is used for PAL systems in Australia and 60 Hz is used for NTSC displays (North America)

When TV jumped to the digital age they were able to fire all of the Pixels (or leds) at once to show a complete screen typically around 60 Hz.

The actual rate is 59.94 p (progressive rather than interlaced) for HDTV in the USA using the NTSC system. Meanwhile 50 Hz is still used for PAL digital displays (the incoming signal). Some brands oversample and estimate what screens in-between the incoming screen signals might be, and they might double or quad oversample to display FOUR times the amount of screens (ie 50 Hz incoming becomes 100 Hz or 200 Hz displays).

What the HUMAN flicker rate has to do with it

“The human flicker fusion rate (FFR) is the number of times per second that a light source must be turned on and off for the human eye to perceive a continuous light. The FFR is typically around 60 Hz, but it can vary depending on the brightness of the light, the size of the light source, and the individual’s age.” Ref 2

“A TV frame rate is the number of times per second that a new image is displayed on the screen. A 25 Hz TV frame rate (IN AUSTRALIA) means that a new image is displayed 25 times per second. But this is ‘interlaced’ or displayed at essentially twice that rate (making it 50 Hz).  This is slightly lower than the human FFR (60 Hz), but it is still high enough that most people do not perceive any flicker.” Ref 2

“There are a few reasons why this is the case. First, the human eye is not very sensitive to flicker at low brightness levels. A 50 Hz TV screen will appear to flicker less at lower brightness levels than at higher brightness levels.

Second, the human eye can also compensate for flicker by averaging the brightness of multiple frames. This means that even if the TV screen is flickering, the eye will still perceive a smooth image.”  Ref 2

 WHY YOUR DOG HAS A FASTER FLICKER RATE

Dogs have amazing vision.  Better at night, though less resolution than humans and less colour detection, but better at detecting moving objects. This potentially evolved to catch prey, but is also useful in modern days for catching balls and frizbees.

They say that while most humans have a flicker rate of around 60 Hz, dogs flicker rate can be up to 80 Hz depending on the breed and other factors.

“The flicker fusion rate is the point at which rapidly flickering light appears to meld into a constantly illuminated light. This is important when presenting videos as these rely on presenting a rapid succession of static images. If the frame rate, in Hertz (Hz), is below the threshold of sensitivity, the flicker will be viewable and the film will appear jerky.” Ref 1

This all suggests besides many dogs being super athletes, that they can also see at such high flicker rates, that they have a natural advantage in targeting objects (that treat you throw into the air). It is like they are slowing down time, compared to humans.

It also means that if your digital TV, anywhere in the world runs at the maximum of 50-60 Hz, DOGS will see a jerky image, not a smooth realistic video. Humans get headaches form this, so we can assume it isn’t that comfortable for dogs either.

CONCLUSION AND TIPS for your dogs TV VIEWING PLEASURE.

While mostly higher-end TVs tend to have quality multiple extra frame rate sampling there are ways around this flicker frame rate dilemma for your dog.

Did you know that quite a few TVs have ‘motion flow’ or ‘smoothing’ video functions that you can select under the VIDEO section of your TV settings.

If you wish to have your dog as interested as you in some programs, and keep their brain happy – perhaps consider buying higher frame rate TVs and / or using the motion flow options (that do a similar thing to adding more frames.

Reference

REF 1 Byosiere, SE., Chouinard, P.A., Howell, T.J. et al. What do dogs (Canis familiaris) see? A review of vision in dogs and implications for cognition research. Psychon Bull Rev 25, 1798–1813 (2018). https://doi.org/10.3758/s13423-017-1404-7

REF 2  Bard  Google