# Is "screen door" effect an unavoidable artifact of digital cable? **URL:** \ **Category:** Factual Questions\ **Created:** [January 22, 2009, 8:20pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514 "2009-01-22T20:20:02Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Freejooky](https://avatars.discourse-cdn.com/v4/letter/f/ba8739/32.png) [@Freejooky](https://boards.straightdope.com/u/Freejooky)\ **Post date:** [January 22, 2009, 8:20pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/1 "2009-01-22T20:20:02Z")
I have digital cable on a standard TV. Frequently, there is a “screen door” effect on the picture, usually noticeable when there’s a lot of movement - it’s like there are scan lines on the image or something like that. It’s not that traditional blocky/pixellated look of digital interference. Is this something that I’m just sensitive to that’s going to be present regardless? ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [January 22, 2009, 10:44pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/2 "2009-01-22T22:44:44Z")
I’m not sure what you are seeing. On some digital televisions there is visible pixellation especially when there is a lot of motion, such as big splashes of water or maybe a pile of leaves being blown. The trouble is that many pixels must be changed by large values in a short period of time, and the necessary compromises are worse. There is also a different effect when subtle gradations in color or shade span a large part of the screen, such as in a view of a sunset where the sky is cloudless. You can then see contour lines where the color values are changing. Neither of these sounds exactly right, though - can you say more? ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [January 22, 2009, 10:47pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/3 "2009-01-22T22:47:58Z")
That’s interesting. Sounds like compression artifacts due to video streams that have more updates to do to your screen than you have bandwidth for. Check out this: [http://hpr1.com/tech/article/digital\_tv\_is\_coming\_beware\_of\_artifacts/](http://hpr1.com/tech/article/digital_tv_is_coming_beware_of_artifacts/) or just Googol digital tv artifacting ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [January 22, 2009, 10:54pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/4 "2009-01-22T22:54:07Z")
What you’re probably seeing is interline twitter: [Interlace - Wikipedia](http://en.wikipedia.org/wiki/Interlace#Problems_caused_by_interlacing) Not a lot you can do about it. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [January 23, 2009, 1:24pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/5 "2009-01-23T13:24:56Z")
I’m hung up on the OP’s word “unavoidable”. No, there’s nothing you can do about it, not right now anyway. But the cable company can fix it, by increasing bandwidth so that it won’t needs to compress the signal past the breaking point. But that would cost money, and then you’ll be able to decide whether or not you want to pay the higher rates. I see this sort of thing on my cable system too. Does dish technology not suffer from similar compression problems? ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [January 23, 2009, 2:27pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/6 "2009-01-23T14:27:30Z")
Dish technology [which for me means Fox News in the cafeteria at work] seems to have almost no instances of this problem. Even fast-moving video of ‘breaking stories’ doesn’t futz it up. Satellite doesn’t have the problem of oversold shared neighborhood “loops”. The Satellite guys ALWAYS have to have enough bandwidth… Time Warner is hoping that all of me and my neighbors won’t watch ALL of the channels at once. ---
**Author:** ![flex727](https://avatars.discourse-cdn.com/v4/letter/f/258eb7/32.png) [@flex727](https://boards.straightdope.com/u/flex727)\ **Post date:** [January 23, 2009, 10:35pm UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/7 "2009-01-23T22:35:04Z")
> [@Mr.Slant](#): > > The Satellite guys ALWAYS have to have enough bandwidth… Time Warner is hoping that all of me and my neighbors won’t watch ALL of the channels at once. I don’t think this is true (unless you’re just referring to VOD). It probably is true for an IPTV service such as U-VERSE, but not cable. On cable, every channel has its own allocated bandwidth all the time. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [January 24, 2009, 12:20am UTC](https://boards.straightdope.com/t/is-screen-door-effect-an-unavoidable-artifact-of-digital-cable/482514/8 "2009-01-24T00:20:28Z")
This is most likely due to to overcompression. They are trying to compress more to squeeze in extra channels. The cable company needs to upgrade it’s capacity or scale back its channels