Understanding printer specs

ehrenfest

I'm a college students looking to buy a printer/scanner/copier combo. As I am very cheap, I am trying to understand the printer specifications in order to ensure that I buy the cheapest printer that has the features I want and as little else as possible.

I am leaning towards http://www.officedepot.com/a/products/102050/HP-Officejet-J4580-All-In-One/". I am trying to understand what specifications such as the following mean:

maximum black and white print resolution 600 x 600 dpi
maximum optimized color print resolution 4800 x 1200 dpi
maximum true color print resolution 4800 x 1200 dpi
maximum black and white copy resolution 600 x 1200 dpi
maximum color copy resolution 4800 x 1200 dpi
scanner optical resolution 1200 dpi
maximum scanner color depth 48-bit
maximum scanner resolution (interpolated) 1200 x 2400 dpi

Why are there two numbers for all of the resolutions except the "scanner optical resolution" ? Can someone explain what the first number and the second number means? Which of the different resolutions should I care about? What is the "maximum scanner color depth" ? Does anyone know of a good online guide for buying a printer that might explain this stuff?

Also, I can't find on the internet where it says what ink cartridges the printers take. Is it true that printers only take ink cartridges from the brand that made them i.e. HP printers can only use HP ink cartridges?

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Wrichik Basu

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Why are there two numbers for all of the resolutions except the "scanner optical resolution" ? Can someone explain what the first number and the second number means?
Flatbed scanner specifications are stated with two numbers, like 1200x2400 dpi. Flatbeds also usually specify a maximum resolution, like perhaps 9600 dpi.

A scanner scans one horizontal row of pixels at a time, moving that scan line down the page with a carriage motor. The smaller dpi number is the optical resolution of the CCD sensor cells. A 1200 dpi scanner takes 1200 color samples per inch (creates 1200 pixels per inch) horizontally from the width being scanned. A 1200 dpi CCD sensor really cannot do anything else but scan at 1200 dpi. This rating does not mean that it can resolve 1200 lpi in a test target, but instead, the CCD simply reads 1200 samples per inch. Nyquist sampling theory says the image can never resolve more than 1/2 of that detail level, and in the real world, a little less.

The larger dpi number is the possible positioning of the carriage stepping motor. A stepping motor doesn't rotate continuously like regular motors. Instead it is pulsed to move in precise steps, rotating only a few degrees with each input power pulse. A 1200x2400 dpi scanner is geared so that each pulse of the carriage motor moves in 1/2400 inch steps vertically. If we scan at 300 dpi, the carriage moves eight motor steps at a time vertically, then stops and samples, and resamples the scan line to 1/4 size horizontally, to create the 300x300 dpi image requested. If scanning at say 250 dpi, it should move 2400/250 = 9.6 steps per row, but it can only move 10 steps on some rows, and 9 steps on others. Any location error will be less than half a CCD cell height, even in worst case. This is the purpose of the 2X rating of the motor. The purpose is NOT to scan at 2400 dpi. The motor does not contribute to optical resolution. A 1200x2400 dpi unit is a 1200 dpi scanner.

Most flatbed scanners also advertise a "maximum" resolution, 9600 dpi, or even more, but this is a meaningless number. It is simply interpolated resolution (see Chapter 13), and you can do the same thing blowing up the image later in a photo program (except you won't, the quality is blurred, not improved). Resolution greater than the CCD optical rating is simply interpolated resolution, done in software after the 600 or 1200 dpi optical scan. Interpolated resolution is the least important scanner specification. It was useful for line art mode, and only for line art, to reduce jaggies when we had 300 dpi scanners and needed 600 dpi line art.

Source:

What is the "maximum scanner color depth" ?
Color or bit depth is the amount of information the scanner gathers about the document or photo you’re scanning: The higher the bit depth, the more colors are used and the better looking the scan will be. Grayscale images are 8-bit images, with 256 levels of gray. Color images scanned with a 24-bit scanner will have nearly 17 million colors; 36-bit scanners give you more than 68 billion colors.

Source:

Also, I can't find on the internet where it says what ink cartridges the printers take. Is it true that printers only take ink cartridges from the brand that made them i.e. HP printers can only use HP ink cartridges?
Yes, you can, but you have to specifically search for those cartridges that are supposed to work for your printer. Generally the site/shop from where you buy will have the information. Another option is to buy an original cartridge and refill it when it is empty.

"Understanding printer specs"

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