"John Lee" writes:
I am considering a new computer but monitors are causing me some confusion.
My digital images are in 4:3 proportion and I want naturally to preserve
that layout on a new LCD/TFT. But the vast majority of monitors today are
widescreen. I do not want images to be stretched.

It's normally not a problem on PCs. Standard LCD monitors for PCs all
have square pixels, whether the screen aspect ratio is 4:3, 5:4, 16:9,
16:10, or something else. In normal use, you set the graphics card
resolution to exactly match the display, so one pixel in the graphics
card is exactly one pixel on the display. And the pixels in your camera
images are *also* square. So when you display your photos on the
screen, the display program uses however many pixels it needs (possibly
after reducing the image size, if it won't fit) and it ends up the right
shape - but not totally filling the screen. Depending on the display
program you use, you can have the rest of the screen black, or grey, or
just outside the image border.

One place where you *can* get weird results on a PC is if you set the
graphics card to a different resolution than the monitor. In that case,
the monitor may have different methods to handle the "wrong sized" input
image. I have a Dell monitor with 3 choices:
1. always stretch to fill the screen, both horizontal and vertical
2. make the image as large as possible while preserving aspect ratio
3. use 1:1 mapping from input to display pixels

The first of these can distort the image shape; the other two do not.
For example, the monitor's native resolution is 1920x1200 (16:10). If I
set the graphics card to 1024x768, then in mode #1 the monitor would
stretch that to 1920x1200, badly stretching the 4:3 source out to 16:10.
In mode #2, it would stretch the image to 1600x1200, preserving the 4:3
aspect ratio (and leaving black bars on the sides). In mode #3, it
would display the image using the centre 1024x768 pixels, with black
bars on all 4 sides - no interpolation at all.

The other place where you have to watch out is digital video, where most
standard formats do *not* have square pixels.

Dave