Xerox 701P44148 manual Two faces of resolution

9. Hints and tips

The key to successfully editing, scanning, and printing images lies in understanding how pixels transform into inches and vice versa. Resolution is the interpreter between the physical world of inches and the digital world of pixels. When you scan an image, the scanner translates inches into pixels using resolution. When you print an image, the printer translates pixels into inches using resolution. So what's resolution? Unfortunately, the word is used in different ways in different contexts. "Camera resolution" usually means something slightly different from "image resolution,” and "printer resolution" is something else yet again.

The two faces of resolution

“Resolution” is used in two basic ways. In some contexts, resolution refers to the pixel count of an image. An image with lots of pixels is often called a "high resolution" image. However, in other contexts, resolution refers to the density of pixels in a given linear area such as an inch. This "density" is expressed as ppi (pixels per inch) or dpi (dots per inch), and this density number is embedded invisibly in a bitmap image, as an instruction to output devices, such as a printers. For clarity, we will refer to the first type of resolution as pixel count resolution and the second as embedded resolution.

The difference between pixel count resolution & embedded resolution

Embedded resolution tells your printer how far apart to spread the pixels in a printed image. It determines how "fine grained" the printed image will look. It is completely independent of the pixel count of the image. A high-pixel-count image can have a low embedded resolution or vice versa. Embedded resolution is inversely proportional to the size of the printed image. Given the same pixel count, a high embedded resolution will result in a smaller printed image (the pixels are packed together more tightly), and a low embedded resolution will result in a larger image (the pixels are more spread out).

Embedded resolution, however, does not affect the size (in bytes) of your image or its appearance on a computer screen; those properties are determined solely by the pixel count. The byte-size of the image file is directly proportional to the pixel count, as is its size on your computer screen, which simply displays all the pixels in the image in a fixed one-to-one grid.

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