Printer Services Newsletter 5.2
Australian Printer Services would like to welcome you to the second half of 2015 and our latest series of informative newsletters about printers and multifunctions. This time we would like to shed some light on print resolution and why 600 x 600 can create a better image than 1200 x 1200.
Understanding 4-bit depth Print resolution capability is typically measured in dots per inch (dpi); however, a laser “dot” can behave differently depending on the output device. Xerox colour printers and multifunction printers with 4-bit depth colour technology are rated at 600 x 600 dpi, but can produce output that compares well to devices rating a much higher dpi resolution. Here’s why:
Dots per inch
In specifications for laser printers and multifunction printers, print resolution is listed as horizontal dpi by vertical dpi. Some common examples are 600 x 600 dpi or 1200 x 1200 dpi. Higher dpi numbers correspond to smaller dots when printing an image. In general, devices with higher dpi can produce finer lines and more detailed output.
Horizontal dpi is determined primarily by the laser used in the device, and the size of the dots the laser utilizes as it scans side-to-side when preparing the image to be printed. Vertical dpi is determined by how quickly the device moves paper through the engine when printing. A device outputs pages slower in 1200 x
1200 dpi mode than it would in 1200 x 600 dpi mode.
Each of these examples uses 1-bit depth. That means that in each dot position the device can print no dot, or a dot consisting of a fixed volume of toner. Another way of listing these resolutions would be to add bit-depth to the description: 600 x 600 x 1 dpi or 1200 x 1200 x 1 dpi.
With 4-bit depth, a device can produce variable toner volumes at each dot position. This creates more options for each dot than just “on” or “off.” Each dot can have multiple shades of colour — as many as 16 shades per dot. The resulting image will have smoother colour transitions with more colour levels than the
image printed by a traditional 600 x 600 (x 1) dpi device. The output can appear similar to — or even superior than — output from 1200 x 1200 (x 1) dpi devices.
The bottom line
When evaluating colour output quality, look beyond the dpi numbers.
By virtue of the equal shades of colour possible per 600 x 600 dpi pixel space, and the equivalent amount of data used to render colour gradation and quality, 600 x 600 x 4 dpi printers are able to intelligently optimize the outputted image and make it comparable to 1200 x 1200 dpi.
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