Hi Howard, I think I’m doing everything right, but I’m always disappointed when I play back a recorded image. The image on the monitor is not as sharp as it should be. I’m using brand name hi-resolution cameras and my recorder is set at 640x480. Why don’t the images look as good as they should? Thanks for your help. - Jim R., Nashville TN.
Hi Jim, the problem is not with your equipment. It’s the NTSC standard that was established in the 1940’s. NTSC images are not really pictures but a series of lines painted on the screen so fast that they appear to be solid. Although NTSC is technically 525 lines of resolution, only 480 of those lines are used to make the visible mage. The remaining lines contain information pertaining to picture synchronization, vertical retrace, and other data such as captioning which aren’t seen. Anyway, each frame is done in two passes. The first pass (field) is 262.5 odd lines, the second pass is the 262.5 even lines. Combining the two passes we get the 525 lines in a frame. There is a 1/60th of a second delay between the start of each field. Recorders can’t record both fields because any movement in the picture would create a blur between neighboring lines. That means the best any recorder can record is 240 lines per picture. We’re using a big fat crayon to paint a detailed picture. The advice would be if you need detail then you’ll need to get your image close to the subject. The good news is that certain camera manufacturers are addressing this shortcoming by developing non-interlaced cameras with more than 525 lines. It will only be a matter of time before the NTSC standard becomes obsolete. - Howard
UPDATE....HI-DEFINITION CCTV TO THE RESCUE!
The good news is that Mega-pixel technology is here. Mega-pixel delivers a picture that is clear and sharp in live monitoring as well as video playback situations. It has better picture quality than 1080p high-definition. Look for many new products as the mega-pixel revolution takes hold. Videoguard is proud to be the first in the area to offer mega-pixel cctv.
