Know its difference: Interlace Vs Progressive scanning.

Resolution is the main reason that makes the HD TV stand out from the rest. An image displayed on the screen is made up of millions or more number of pixels. Resolution of an image displayed on the TV depends on the number of pixels, more the number of pixels better is the resolution.

Based on the number of pixels and the way the image is shown on the TV, it can be classified in 4 types: 1080i, 1080p, 720p and 576p. We have discussed about the types in detail in this post: Difference between 1080i and 1080p.

The ‘I’ and ‘p’ represents the type of scanning used to display the image. ‘I’ stands for interlace and ‘p’ stands for progressive. For better understanding consider each row of pixel as one line.

Interlace scanning:

Interlacing divides each line into odd and even ones and then alternately scans and refreshes them at 30 frames per second. The slight delay between odd and even line refreshes creates some distortion or flicker. This is because only half the lines keep up with the moving image while the other half waits to be refreshed. This type of scanning can be commonly seen in the traditional CRT monitors.

Progressive scanning:

With the advent of LCD (Liquid Crystal Display) more efficient and better way of scanning the image was introduced know as ‘progressive scanning’. Unlike a interlace system which scans odd and alternately even lines (1,3,5 etc and 2,4,6 etc..) every 1/30^th of a second, progressive system scans the line sequentially (1,2,3…) every 1/60^th and produces a complete and flicker less picture. Using progressive scanning, a smoother and much detailed image with finer details can be produced.

1080i and 1080p are the two most commonly used resolution for HD TV. Although 1080p is better than 1080i, native content available in 1080p format is considerably less and conversion of 1080i to 1080p does not always provide the same result. If you are using blu ray or PS3 with 1080p you can opt for a TV with 1080p resolution.

Difference between interlace and progressive scanning

• Interlace scans odd lines first and alternates to scan even lines whereas a progressive system scans sequentially.
• Interlace scans every 1/30^th of a second and progressive every 1/60^th.
• Progressive produces much better and finer picture quality.
• Less native source is available in 1080p format.