TV resolution is measured by rank and file. Therefore a TV picture of 720 x 480 would have 720 dots going across the horizontal axis of the screen, and 480 dots on the vertical axis. These rows of dots would describe rows of pixel points 720 rows of dots from the horizontal, ( these rows would actually run from top to bottom VERTICALLY)! Then the 480 lines of vertical resolution would actually run HORIZONTALLY from side to side of the screen. Basically, what is being described is a matrix. Picture a checkerboard with 720 squares in 1 direction and 480 squares in the other. The total number of "pixels" in the screen would simply be 720 multiplied by 420, which equals 345,600.
In the reproduction of a color picture by a CRT each "pixel" actually consists of 3 apertures in a screen, each being targeted by one of three different color "guns", a red, blue, and a green.
TV pictures are created by (originally) a crt electron beam SCANNING from
upper left, horizontally to the right and moving down until it reaches the lower right
of the screen . 420 Lines means that it take 420 scans to get the job done.
This is repeated 60 times per second.
The more LINES, the better the picture; this is what HD tv is all about too
There is more to the issue than lines of resolution. Most important are quality of optics, and type and quantity of light present. Sufficient light gets rid of noise in video sensors thereby increasing apparent resolution. Using crappy lenses should speak for itself. At the end of the day security cameras that work well cost much. I believe that the standard NTSC TV resolution of 680 X 480 lines is about what a decent security should spec to.