How big is a pixel?

how many millimeters?

[txbakers]

So, just how big is a pixel? Can I make a direct translation to millimeters?

[edited by: txbakers at 5:55 am (utc) on Sep. 27, 2002]

[tedster]

The size of a pixel varies according to screen resolution. For instance, you can take a 17 inch monitor and set that for 800px by 600px, or perhaps 1600px by 1200px.

In each dimension the "size" of a pixel in the second case will be half that of the first case. Therefore the pixels in the second case will be 1/4 the area of the pixels in the first case. But both are still one pixel!

[txbakers]

I was afraid of that. And stylesheets don't recognize decimal intervals, right? I can't specify 24.4mm or 1.5in can I?

Hm.

[Key_Master]

Stylesheets do recognize decimal intervals like the example below.

div {
margin-left: 1.5in;
}

Inches and millimeters are absolute length units and pixels are a relative length unit.

[txbakers]

I got odd results when I tried to use inches with decimals in the following CSS:

<DIV STYLE="position:absolute;
left:<%=hor[colnum]%>mm;
<% if (rownum == 0 && firsttime == 1) {
verti = .5;
firsttime = 0;
} else {
if (rownum == 0 && colnum == 0) {
verti += 1.5;
} else if (colnum == 0){
verti += 1
}
}
%>
top:<%=verti%>in;
font-family:<%=ffamily%>;
font-size:<%=fsize%>; }

I'm still tweaking my 3 X 10 labels from the browser. When I used pixels: 96/inch it seemed to work, I tested it at several resolutions and it printed the same page each time. (which is good!)

[Key_Master]

Found a good reference to length units here:

[w3.org...]

[ann]

I read where 72 pixels=1 inch

Ann

[Purple Martin]

Monitors are (usually) assumed to be 72. "dpi" means "dots per inch", which is another way of saying pixels per inch.

That's why, when you create a new image in Photoshop or Paint Shop Pro or other similar program, it usually wants to default to a resolution of 72 dpi. Note that the word "resolution" means something slightly different from what you may be used to (for example saying you have your screen resolution set to 800x600, which is actually a misuse of the word).

If you want to to print something without it looking blocky, you'd want to choose a much higher resolution such as 300 or 600 dpi.

So that's how those kind of pixels work.

There is another sort of pixel: put you face very close to your monitor, so that you can see the individual red, green and blue dots (if you're lucky enough to have good eyesight). Each set of three dots (one red, one blue, one green) is called a pixel. The size of these pixels obviously varies according to the monitor manufacturer. Computer monitors have fairly small pixels because you generally sit within about 1 metre of the screen, whereas televisions have bigger pixels as you generally sit much further away.