vertical/horizontal sync in video

Video Is Composed of a Series of Still Images.
changing fast enough that it looks like continuous motion.
timing informations are called vertical sync/horizontal sync.

vertical sync - indicates when a new image is starting
horizontal sync -indicates when a new scanline is starting

Each still is composed of series of scanlines.

Interlaced vs Progressive:
For displays that "paint" an image on the screen, such as a CRT,
Interlaced-each image is displayed starting at the top left corner of
the display, moving to the right edge of the display.

Interlacing: First odd number of pixels are sent to display and then
even number of pixels are sent to display the image.
Advantage: we can reduce memory transfered to display by half for every image.

Progressive: pixels are displayed by sequence of lines.For Higher
resolution, we go for progressive.
Interlaced: First half of image is displayed on screen and then next
half of image is displayed