How big is the world's smallest pixel?

Answer 1

By definition, a pixel is the smallest unit of graphics on a computer. A pixel is a universal size and has no variation. Therefore all pixels are the same size.

Now for the REAL ...

I have seen 2880dpi printers. We'll call each of the dots they lay down a pixel. Those pixels are 0.00034" in diameter.

ACTUALLY

the dpi of a printer does not refer to screen pixels but to line screen - each screen pixel requires several "lines" to be able to create all the necessary colors and shades from a printer - a 2400 dpi printer uses 8 lines, or dots, to create all its colors so its resolution is only 300 ppi or pixels per inch - the 2880 dpi printer mentioned above uses a 8 line screen also so its resolution is 360 pixels per inch which as far as i know is the highest res you are likely to find.

also printers don't print exactly to the stated size - print a line 300 pixels long on a 300 ppi printer and its not likely to be exactly one inch - and the horizontal and vertical dimensions are rarely the same either so dots/pixels from a printer are not usually perfect squares

It's me again...DPI and line screen are two TOTALLY different animals.

I'm going to take a real-world example from my own past: the Scitex Dolev4Press laser plotter. (In the world outside Scitex this is called an image setter.) This machine exposes film to make printing plates from, and it has five resolutions: 80 dots/mm (2032dpi), 100 dots/mm (2540dpi), 120 dots/mm (3048dpi), 140 dots/mm (3556dpi) and 160 dots/mm (4064dpi). Out of the box there were several line screens: 66 lines per inch (lpi), 85lpi, 100lpi, 133lpi, 150lpi, 175lpi, 200lpi and so on. In reality, you could open the "screening" dialog on your RIP and plug in any line screen, dot angle and dot shape you wanted. Most Scitex operators do.

DPI translates to line screen through the concept of the Super cell--a group of dots. We'll make the math easy and say we're running a 100-line screen at the 100 dots/mm setting. Each super cell is a 25x25 grid of dots--the actual line screen is a hair over 100lpi, to absorb the extra 40 dots per inch. As the machine prints, it will print some of the dots in the cell and not print others--the more that get printed, the darker the dot looks.

It's possible to print without "line screen." My Mutoh and Vutek printers do that. It's called "stochastic screening." Describing that would require a book, of which many have been written, but it produces print without super cells. This makes sense because dot screens are needed on printing presses but you don't need them on ink jet printers.

Now let's talk vertical and horizontal resolution. The most popular head on the market is made by Seiko Epson--it's in Epson's printers, plus Mutoh and Mimaki eco-solvent wide-format printers. It consists of a plate with holes laser-etched in it every 1/720" and a metal piece that changes shape when electricity hits it. That's your vertical resolution, and unless you've got an extremely precise media drive system in your printer that won't change. Horizontal resolution is governed by the motor that pulls the head back and forth across the page, and that CAN change--when they talk about 2880dpi printers, they're referring to a 2880x720 printer.