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This is about improving motion clarity, so each displayed frame of moving content looks crisp rather than having blur (something that monitors can struggle with

This is about improving motion clarity, so each displayed frame of moving content looks crisp rather than having blur (something that monitors can struggle with even at high refresh rates / high Hz). Most good monitor reviews of high Hz displays (eg: 120Hz+) take fast photographs of moving objects (typically from Blur Busters' 'Test UFO' web page) to demonstrate how good or poorly a monitor handles fast moving content. One technique of significantly improving motion clarity is inserting frames of pure black in the display output (aka BFI, black frame insertion). A downside is some are sensitive to this where it causes eyestrain. This CRT beam simulating shader is said to be similarly effective to BFI at improving motion clarity but with the benefit of reducing eyestrain. However from what I understand the current version is limited to simulating a lower Hz display and requires a higher Hz monitor. All this is distinct from the kind of in-media motion blur that can be enabled in games or seen in recorded video. It's instead about the monitor not being able to render fast moving content clearly enough which leads to non-crisp output frames.

stevage 2y ago
Thank you, that's a really great explanation.
noduerme 2y ago
What is the method used on newer TVs that attempts to double the framerate / interpolate frames / make everything shot on film look like an overlit soap opera? I find it impossible to watch; it destroys the lighting and the performances. My recollection of CRT TVs was that they had a lot of blur, both motion and spatial, and that was kind of what made them feel warmer and more analog / less overly crispy.
- Springtime 2y ago
  That's typically called 'motion smoothing' and yeah that's trying to interpolate frames to manipulate lower framerate video (like 24FPS) into higher framerates in an attempt to make scenes like panning shots 'smoother' at the expense of a soap opera feel and interpolation artifacting. Whereas what Blur Busters (and similar enthusiasts) are focused on is how accurately frames are (perceptibly) displayed on the screen, so ideally each input frame is perfectly presented without any interference from prior frames (due to limits of panels in keeping up with changing the pixels from one frame to another, very rapidly, causing blurring). The ultimate goal, in a perfect scenario, is for input from say a video game running at 60 frames per second to have each frame perfectly rendered like individual screenshot stills, one after the other. In reality for most monitors displaying such content there's not enough distinct separation between frames, leading fast changing pixel content (like objects moving) to blend into each other, causing blurring at the monitor level. The BFI technique, by inserting alternating black frames in the output, mitigates the inter-frame blending issues since instead of the prior frame being various colors (ie: of the prior input frame) it's starting from pure black which dramatically reduces frame blending artifacts and perceptibly makes the motion clarity more distinct.
  - CuriousSkeptic 2y ago
    It’s not that the frames blend in the screen. Screens are perfectly capable of switching the pixels fast enough. It’s rather that each frame is displayed for to long. In a CRT the “pixels” start to fade immediately leaving the full screen mostly dark as the beam sweeps over the screen. It never shows a full frame. One could say that modern screens are more like slide shows, while BFI tries to make them more like stroboscopes. The blurring effect is more pronounced ate low refresh rates, its just that BFI requires at least 120hz to male sense at all.
    - fulafel 2y ago
      CRTs don't darken that fast, one way to observe this is that CRTs don't appear black in photos/video with shutter times << 1/60
      - yuriks 2y ago
        They do darken that fast (not fast enough you can't catch it in a high speed camera, but much faster than a frame). Most of the apparent persistence in the CRT comes from the retina/camera exposure, not the phosphor. A CRT has a sharp peak of light that quickly falls off, but the peak is bright enough that even though it is brief, when averaged out in an exposure in the camera it still appears bright enough to form an image.
      - chowells 2y ago
        You've never taken photos of a CRT, have you? Even at like 400 ISO equivalent, only about a third of the screen is illuminated.
      - rcxdude 2y ago
        They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: https://www.youtube.com/watch?v=3BJU2drrtCM https://www.youtube.com/watch?v=3BJU2drrtCM)

stevage 2y ago

Thank you, that's a really great explanation.

noduerme 2y ago

What is the method used on newer TVs that attempts to double the framerate / interpolate frames / make everything shot on film look like an overlit soap opera? I find it impossible to watch; it destroys the lighting and the performances. My recollection of CRT TVs was that they had a lot of blur, both motion and spatial, and that was kind of what made them feel warmer and more analog / less overly crispy.

Springtime 2y ago
That's typically called 'motion smoothing' and yeah that's trying to interpolate frames to manipulate lower framerate video (like 24FPS) into higher framerates in an attempt to make scenes like panning shots 'smoother' at the expense of a soap opera feel and interpolation artifacting. Whereas what Blur Busters (and similar enthusiasts) are focused on is how accurately frames are (perceptibly) displayed on the screen, so ideally each input frame is perfectly presented without any interference from prior frames (due to limits of panels in keeping up with changing the pixels from one frame to another, very rapidly, causing blurring). The ultimate goal, in a perfect scenario, is for input from say a video game running at 60 frames per second to have each frame perfectly rendered like individual screenshot stills, one after the other. In reality for most monitors displaying such content there's not enough distinct separation between frames, leading fast changing pixel content (like objects moving) to blend into each other, causing blurring at the monitor level. The BFI technique, by inserting alternating black frames in the output, mitigates the inter-frame blending issues since instead of the prior frame being various colors (ie: of the prior input frame) it's starting from pure black which dramatically reduces frame blending artifacts and perceptibly makes the motion clarity more distinct.
- CuriousSkeptic 2y ago
  It’s not that the frames blend in the screen. Screens are perfectly capable of switching the pixels fast enough. It’s rather that each frame is displayed for to long. In a CRT the “pixels” start to fade immediately leaving the full screen mostly dark as the beam sweeps over the screen. It never shows a full frame. One could say that modern screens are more like slide shows, while BFI tries to make them more like stroboscopes. The blurring effect is more pronounced ate low refresh rates, its just that BFI requires at least 120hz to male sense at all.
  - fulafel 2y ago
    CRTs don't darken that fast, one way to observe this is that CRTs don't appear black in photos/video with shutter times << 1/60
    - yuriks 2y ago
      They do darken that fast (not fast enough you can't catch it in a high speed camera, but much faster than a frame). Most of the apparent persistence in the CRT comes from the retina/camera exposure, not the phosphor. A CRT has a sharp peak of light that quickly falls off, but the peak is bright enough that even though it is brief, when averaged out in an exposure in the camera it still appears bright enough to form an image.
    - chowells 2y ago
      You've never taken photos of a CRT, have you? Even at like 400 ISO equivalent, only about a third of the screen is illuminated.
    - rcxdude 2y ago
      They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: https://www.youtube.com/watch?v=3BJU2drrtCM https://www.youtube.com/watch?v=3BJU2drrtCM)