Confusing and Conflicting Terms
There are a lot of confusing terms in digital photography, and even experts and manuals do not use these terms correctly or consistently. Throughout this book the most common usage has been emphasized, but you may read articles where some terms are used differently than the way this book has defined them.
Some of the most frequently confused terms were covered in this chapter:
Resizing: can mean resampling, but it is sometimes used to mean printing the same image at a smaller size without changing its size — which means that it is now printing at more dots per inch (dpi).
Dpi: (dots per inch) is often used interchangeably with ppi (pixels per inch). See Chapter 20 for more about this.
Pixel dimensions: usually means the pixel height by the pixel width, but some software uses it to mean the pixel count or total size of the image.
Interpolation: is sometimes used instead of the terms
To indicate the resolution a camera is capable of recording, the terms
In a similar way, manufacturers of computer monitors use “resolution” to describe the number of pixels the monitor can display. On most monitors you can choose from display settings of 640×480 pixels (VGA resolution), 800×600 pixels, or 1024×768 pixels (XGA resolution). The ppi of your monitor depends on its physical size, plus the display setting you choose.
Monitors are commonly set to display 96 ppi. Older Macintosh monitors are usually set at the factory to display 72 pixels per inch. Fortunately, the math for image display on a monitor is simple, as they are both measured in pixels. One pixel in an image will display as one pixel on a monitor. So, for example, a 640×480 picture will display just fine — with room to spare — on a monitor with a resolution of 800×600.
Just like digital cameras and monitors, scanner capabilities also are described in terms of resolution. Luckily, scanner resolution is usually spoken of in the same terms as image resolution. A low-end scanner commonly captures a maximum of 300 or 600 pixels per inch.