Resolution is a complex subject in some ways, even though most people using a computer may not think about it often.
I wrote about display resolution last column, but that is not the entire story! The resolution used to show you the contents of your computer only shows you what you have in your image, but image resolution determines the quality of the image.
Image resolution describes the detail that an image holds. It can be measured by quantifying how close lines can be to each other and still be visible. Line pairs are often used instead of lines – a pair of adjacent dark and light lines. A resolution of 10 lines per millimetre means 5 dark lines alternating with 5 light lines. Photographic lens and film resolution are most often quoted in line pairs per millimetre.
Most commonly image resolution is described as a pixel count in digital imaging.
It is generally measured as pixels per inch (ppi), and the higher the number, the clearer and higher the quality of the image. This is not to be confused with dots per inch (dpi) that describes the way an image will be printed or displayed, though there is a direct relationship between the ppi and the print size of the image. I will discuss resolution in relation to printing next week.
Some image file formats allow you also to ‘compress’ the image. JPG compression analyses blocks of 8×8 pixels and selectively reduces the detail within each block. At higher compressions, the actual block pattern becomes visible and the loss of detail is noticeable.
Vector images however are not made up of a series of dots but the objects and shapes are defined mathematically and therefore are independent of resolution, meaning they can be enlarged without pixilation and cannot be compressed.
Display resolution in computer terms refers to the number of pixels that can be displayed on the dimensions of your monitor.
When we talk ‘display resolution’ we are talking about the number of actual pixels in columns and rows that fill up your monitor display.
For example, a resolution of 1280 x 1024 means you are displaying 1280 pixels across the screen and 1024 pixels down the screen.
This is different to talking about the resolution of the display, which is given typically as the number of pixels per inch, which will indicate the quality of the image, say in a photograph.
This makes understanding resolution quite difficult at first as the term ‘resolution’ is used interchangeably but has quite different meanings.
The eye’s perception of the ‘display resolution’ can be affected by a number of factors such as the rectangular shape of the screen known as the ‘aspect ratio’. A display with a ratio of 1280 x 720 on a 16:9 display will have square pixels, whilst 1024 x 780 on the same display will have rectangular pixels.
This will affect the perceived sharpness – displaying more information in a smaller area results in a higher resolution, and makes the image clearer.
Basically the importance of this for the computer user is how your display resolution settings will affect how things look on your screen.
The higher the numbers on your display resolution will result in smaller individual pixel sizes being displayed. The smaller the size of the pixels on your screen will result in everything looking smaller. This is great if you want to fit more on your screen, but not so great if you find text difficult to read.
There is no ‘right’ resolution, as everyone is comfortable with a different setting, which is why all computers allow you to adjust your resolution to suit your own needs.
