Monitor's Pixels are not Square

Discussion in 'Amateur Video Production' started by Ken, Nov 25, 2004.

1. KenGuest

My monitor's pixels are "rectangular". And oddly, the ratio is the
opposite of DV !!! With DV AVI's using the 0.9 pixel ratio, the width
is 90% the height. They are taller than they are wide.

But my monitor pixels are wider than they are tall. So the height is
quashed down further than it really is !! You can do this test on
your monitor. For example, I created a 400x400 image and viewed it at
100% size on my screen. It measured 6.44" x 5.75" (WxH).

The DV AVI pixel ratio of 0.9 is calculated by w/h. So my computer
screen ratio = w/h = 1.12. But ratios of pixels are usually quoted
at less than 1 so I will use the inverse ratio of h/w = .893 (the
height is reduced by .893). So 480 pixels tall will be reduced in
relative size to a width equivalent to 428.

So for DV AVI's - theoretically, my screen will take a 720x480 image
and display it at a size "equivalent" to to 720x428 for a W/H ratio of
1.68 - I measured a 720x480 image on my screen to test this:

Width x Height = 11.44 x 7
W/H ratio = 11.44/7 = 1.63 (close enough to my theory - it is
proved !!).

The DV ratio has no effect on PC Monitors - whether you export a video
clip using sqare 1.0 pixels, or rectangular 0.9 pixels - the video or
exportes frame images show and play at EXACTLY the same resolution and
size, because the screen has a fixed pixel size !! It always uses the
same pixel ratios regardless. 720x480 shows on my screen as 11.44" x
7" no matter what Premiere exports the video as.

Ken, Nov 25, 2004

2. deco_timeGuest

You never stated what resolution your screen is set at. To get thoses
result, I'm gonna guess 1280x1024, which is 5:4 aspect ratio, and not
4:3; 1280x1024 is the only resolution considered standard with that
weird aspect ratio.

deco_time, Nov 25, 2004

3. Jeff MakeyGuest

To solve this problem on my CRT monitor I brought up a square image
and adjusted the monitor's physical display controls until the image
was square as measured by a ruler. As a result, at 1280x1024
resolution I have black bars about 1/2 inch wide on the sides of my
display. On those occasions when I switch to 640x480 the black bars
are on the top and bottom, letterbox style.

This is the way to do it when undistorted images are more important
than using every square millimeter of your CRT screen.

:: Jeff Makey

Department of Tautological Pleonasms and Superfluous Redundancies Department

Jeff Makey, Nov 25, 2004
4. deco_timeGuest

A monitor is physically 4:3, why not just choose a resolution that's 4:3
to begin with? Just use a resolution of 1280x960, instead of weird
distorted aspect ratio.

deco_time, Nov 25, 2004