On Thu, 30 Jun 2005, Diego Biurrun wrote:
On Tue, Mar 08, 2005 at 12:07:23AM +0100, Diego Biurrun wrote:
On Mon, Mar 07, 2005 at 04:44:21PM +0200, Oded Shimon wrote:
What happens with tearing is that halfway through this process, the image changes - a very likely event. Because of this, the monitor displays the first half the first image, and the next half it shows the new image, thinking it's all the same image. The mistake will be "corrected" in the very next refresh, as then the entire screen will be the new image - too slow. Our eye already caught the mistake. With extremely high refresh rates (150hz+), tearing is practically unnoticeable.
I'm not particularly fond of this paragraph. It could be slightly clearer. Sorry for not being more specific right now..
I must admit I don't get the above paragraph 100%, can somebody elaborate? Rich?
A CRT doesn't display a whole image at once. It updates one row, and then the next row, and so one until the bottom of the screen, and then jumps back to the top ("v-sync") and continues. So at any instant, the top portional of the screen is from one image, and the bottom portion is from the previous image. As long as the image being display only changes during v-sync, you don't normally notice this, because the border between the two images is moving really fast. However, if you change the display part way through the scan, then it's a mixture of 3 images, with one of the boundaries staying still for 1/75 second or so, which is long enough to notice. --Loren Merritt