HD TV (aka 480 vs 720p vs 1080i/p)

Miss J wrote today and said she had just got an high definition (HD) receiver for her HDTV, but hadn’t gotten it to work yet.  While this post won’t go into troubleshooting her specific issue, I thought it would be worthy of discussing “high definition TV” and what all those numbers mean.


Standard Definition (SD) television has 480 lines of video.  You can see them from where you sit but put a drop of water on the screen you can see the red, blue and green dots which make up a single “pixel” of the image.  If you were to count from the top of the screen to the bottom, there would be 480 pixels.

HD starts at 720 lines of resolution, 50% more than SD.  This means higher resolution resulting in clearer, more lifelike images.  HD also uses a wider format, similar to the cinemas.

SD vs HD

Notice how the lower picture is grainy?  How the spotlight shows blocked lines?  Now compare to the upper picture.  It looks clearer, the spotlighted area has much more “information” and the picture shows more along the horizontal plane which is more natural to the eye.

1080 i/p

There is an even higher resolution for TVs out that have 1080 lines of resolution.  The “i” means the video is interlaced.  The “p” means it uses progressive scanning.  The difference in how the image is created.  Interlacing the video “cheats” your eye into thinking it is seeing the full picture, but is basically only showing every other line.  Essentially you see 540 lines in one frame and the other 540 lines in the next.  With 1080p, however it is the full 1080 lines every frame.  The result is a cleaner and crisper picture.  Do you need 1080?  Well, unless you’re looking at a TV larger than 42″, you will barely notice the difference between the 720 and 1080 lines of resolution.

As far as Miss J’s problem connecting her HD receiver and TV, that will probably require a phone call… and another post!  🙂

Posted in 1080i/p, 720p, HDMI, HDTV

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