Shape and size of a Pixel?

x+iy

A pixel is said to be an intersection between horizontal and vertical lines on the screen.

So does this intersection have a physical shape and size and what happens when an image or video of say 1600X1200 is played on screen having resolution of 800X600 or vice versa.

I have searched a lot on google about this topic but more i read more i get confused.
Please explain in layman's term. Also any link to video tutorials will be highly appreciated.

Thanks.

caffenta

Pixel means picture (pix) element (el). In layman's terms: a dot. Not a round dot, but a square or rectangular dot.

If you resize an 800x600 image to 1600x1200, each pixel from the 800x600 image becomes a square of 4 pixels (2x2) in the 1600x1200 image. Since that looks blocky, some kind of interpolation is used during the resizing to make it look smoother.

x+iy

Is the shape of a pixel always square is inherent to the screen? and when a picture of higher resolution is viewed on screen with lower resolution, o pixel shrink to fit in the screen?
Since no. of pixels on the screen (max resolution) are fixed how a image or video of different resolution is viewed?

chiro

Pixels must cover the whole screen within the boundary and the best shape that facilitates this is some sort of rectangle (preferably a square).

There are probably output devices that are different (like say some industrial devices placed out on roads to warn of traffic work or something of that nature), but for something aesthetic like a computer that requires rich amounts of detail and quality, I couldn't imagine the pixel that doesn't join exactly at the edges like a square does.

caffenta

Usually, when you talk about digital images or video, a square/rectangular pixel is implied. For example, open a picture editor (like Paint in Windows), zoom as much as you can and draw a 45-degree line. You'll see the big square pixels. If they were not square, you would not get 100% fill factor.

Physically, a pixel does not have to be square. When you print with an inkjet printer, they are round, but they are bigger than the spacing between pixels so they overlap a little and fill the space.

On an LCD screen, you actually get a screen-door effect because there is a little bit of space between the pixels. However, it's so small that you can't really see it. It was much more apparent on older LCD projectors that had a fairly low resolution.

If the picture/video is not resized, it will be bigger than the screen, so you will only see part of it. If you see the entire picture/video, then it has been resized by the picture/video player.

rcgldr

Some examples of pixels on various types of screens:

http://en.wikipedia.org/wiki/File:Pi...y_01_Pengo.jpg

oled:
http://en.wikipedia.org/wiki/File:Ne...microscope.jpg

Another variation would be an image formed from 3 monochromatic CRT tubes, red, green, blue, as used on old HDTV CRT based rear projection system (Mitisubishi last made these in 2006). Instead of having the colors side by side, they overlap, the result of projected images created from electron beams on each CRT tube. Part of the maintainance is to calibrate the electronics with a grid pattern with the goal of getting all 3 beams to converge to form single lines in that grid pattern.