Choosing a Monitor for Image Editing and Viewing
Much of the fun of digital photography comes from editing images on a computer so choosing the right monitor is important. Two types of monitors are popular: LCD (Liquid Crystal Display) and CRT (Cathode Ray Tube). Although CRT monitors were once favoured by photographers for their colour and tonal accuracy, flat-panel LCD monitors have largely replaced them at all levels of imaging.
All notebook/laptop computers have LCD monitors.
All laptop/notebook computers have LCD monitors so the choice is only relevant when looking at desktop monitors. For a desktop monitor, LCDs have certain benefits over CRTs:
* LCDs can produce perfectly sharp images with no geometric distortions.
* They deliver a consistent tonal scale.
* They are flicker-free and, therefore, easier on your eyes.
* Their colour values remain relatively stable over time.
* Their native interface is ideal for digital applications.
* They are lighter and take up less space.
* They are more energy-efficient and produce less heat.
However, they also have a few disadvantages:
* Contrast and colour can change with viewing angle (although this has little relevance for photographers who view screens ‘straight-on’).
* Individual pixels may ‘die’, causing tiny permanent black dots to appear on the screen.
How Large and How Many?
The size of the monitor you choose will be dictated by two factors: your budget and the amount of space on your desktop. Monitor screens are measured diagonally, and their size is usually expressed in inches. Popular sizes range from 17-inch to 24-inch and many LCD monitors are available in widescreen format (16:9 aspect ratio). The actual hardware that carries the screen can vary significantly, although LCD monitors are usually more compact than CRTs. They are also more freely adjustable.
The standard 4:3 aspect ratio is the most popular for most computers.
However, widescreen displays are becoming increasingly popular.
Widescreen monitors are ideal for image editing as they provide plenty of space for the picture and editing tools.
The most popular (and cheapest) monitor size is 19-inch, with 20-inch and larger screens being used mainly by professional photographers and graphic designers. If your budget and desk space permits, a larger screen will provide a large viewing area with plenty of room for toolbars and palettes when you’re using editing software.
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Monitors for image editing should provide a wide range of adjustments that allow them to be calibrated.
Many photographers prefer working with dual monitors because they can ‘park’ toolbars on one screen, leaving the other screen uncluttered for displaying the image they are working on. This is an ideal working environment for image editing if your desk space permits. Most recent computer operating systems will support dual monitor set-ups.
No laptop LCD can present colours, tones and contrast levels accurately enough to base serious imaging decisions on so they are not really suitable for image editing and printing. They also offer a limited range of adjustments. However, you can improve their accuracy through calibration and profiling, although a colorimeter is normally required for these tasks. This process is outlined in the Monitor Calibration chapter.
Monitor Check List
Before purchasing a monitor for imaging, make sure it has the following features:
1. Brightness, contrast and red, green and blue channel colour adjustments. Some monitors are sold with one or more of these controls locked and this prevents accurate profiling. Screen brightness levels directly affect the ease with which you can discern detail in displayed images. Because we view the monitor from a distance of about 50 cm, high brightness levels are not required for image editing. For this distance, a maximum brightness of 250 to 300 candelas/square metre is ideal, according to the international standard covering flat panel displays.
Contrast levels, however, should be set as high as possible because they produce sharper, ‘crisper’ looking pictures. Adjustable colour controls are vital because they allow you to set the colour balance of the display and ensure the monitor screen displays colours uniformly from edge to edge. Screens that are brighter towards the centre and darker at the edges and those that display colour spots are unsuitable for image editing.
Some monitors have built in anti-glare and anti-reflection filters. These may be worthwhile in home situations where you may not be able to control all aspects of ambient lighting. However, although a screen with anti-glare is easier on the eyes, it may not reproduce the full tonal range in the picture.
Ambient lighting can influence your perception of colour. An image displayed on a monitor will look different when the room light is on from when it is off. Where possible, set your monitor up in a room with relatively low brightness levels and avoid situations in which room lights can be reflected by the screen. Anti-glare hoods are available for some monitors.
Anti-glare hoods are available for some monitors.
2. Adequate Resolution. Resolution refers to the maximum number of pixels (picture elements) that the monitor can display and, therefore, to the amount of detail you can discern in displayed images. However, the higher the resolution, the smaller individual items on the screen become. Most monitors can display a range of resolutions, from 640 x 480 pixels, through to 3200 x 2400 pixels. The ideal resolution for a standard 4:3 aspect ratio display for image editing is between 1280 x 1024 pixels and 1920 x 1200 pixels. Widescreen displays typically range between 1280 x 800 pixels and 1440 x 900 pixels.
3. Pixel Pitch. The pixel pitch of an LCD is the distance between adjacent sets of the pixels that are displayed on the monitor screen, measured in mm. For CRT screens, a more common designation is ‘dot pitch’ or ‘phosphor pitch’. Both terms refer to the diagonal distance between like-coloured phosphor dots on the screen.
For both pixel pitch and dot pitch, the lower the number, the sharper the picture the screen can display. In LCDs, pixel pitch is measured horizontally and vertically, although as the pixels themselves are generally square, sometimes only one dimension is quoted. One number is normally used for dot pitch.
In both cases, it’s important to consider the size, type and native resolution of the monitor when assessing its pixel pitch. On CRTs, dot pitch figures typically range from 0.28 to 0.51 mm, although large presentation monitors may go up to 1.0 mm. On LCD monitors, pixel pitch is typically from 0.16 to 0.29 mm. A pixel pitch of 0.294 ø— 0.294 mm is seen as very good for a 19-inch monitor with a native resolution of 1280 x 1024 pixels.
4. Gamma Correction. The gamma of a monitor screen refers to the luminance (or brightness) of the red, green and blue signals in the display. Gamma correction involves mapping the displayed data to produce a consistent and uniform appearance when images are displayed. This is done by a microprocessor that is part the monitor’s electronic controls.
Professional LCD monitors can be distinguished by 10-bit (or higher) gamma processing, whereas other displays offer only 8-bit support. This difference is significant. Whereas a monitor with 8-bit processing can only calibrate the gamma curve in 256 steps, a 10-bit processor can calculate the gamma curve in 1021 steps and a 12-bit processor can handle 4096 steps. The result will be a smoother gamma curve and greater hue and tonal accuracy. Expect to pay a premium price for a monitor with high-bit gamma processing.
5. Power and Radiation. Look for products with high Energy Star ratings and an Energy Management Option (EMO) that can switch off your computer when you’re not using it and shut it down at night. (You can also view calculations on energy, cost and greenhouse gas emissions savings.) LCD monitors are more energy-efficient than CRTs and laptops use less energy than desktop systems.
Unlike LCDs, which do not emit potentially damaging radiation, CRT monitors can emit radiation at very low frequency (VLF) and extremely low frequency (ELF). Both have been shown to have biological effects – although there is no scientific proof that they can harm people who use a computer in everyday situations.
To avoid potential problems when using a CRT monitor, make sure the monitor conforms to MPRII guidelines, which were established by the Swedish National Board of Testing and sit at least 75 cm from the screen itself. Radiation fields are stronger at the sides and back of the CRT than at the front so stay at least 1.2 metres from them. Turn CRT monitors off when they are not in use.
Some monitors can be rotated through 90 degrees to allow vertical photographs to be displayed at full screen size.
6. Adjustability. The height and tilt of the monitor should be adjustable. Some photographers also prefer monitors that can be rotated through 90 degrees to allow vertical pictures to be viewed at full screen size.
Monitor Colour Spaces
All monitors are designed to display the sRGB colour space, although cheaper monitors often struggle to reproduce saturated colours near the edges of the sRGB gamut. Only the most expensive monitors are capable of displaying colours outside the sRGB space. For most digital camera users, working in the sRGB colour space is ideal because all digital cameras are, by default, designed for sRGB.
However, photographers who prefer to work in the wider Adobe RGB colour space may find that images on sRGB screens will look flat. There’s nothing to stop you from shooting in the Adobe RGB space and editing your images on an sRGB monitor. Although some hues (such as saturated blues and greens) may look slightly flat on screen, with a good inkjet printer, the colours should bounce back, demonstrating that only the monitor display is being clipped; not the file itself.
It’s possible to buy a high-quality screen that displays most – or even all – of the Adobe gamut. However, such monitors are very expensive.
Identifying High-Quality Monitors
There are several ways of checking whether a particular monitor is suitable for image editing. Take a couple of your image files with you when you’re shopping and ask the store staff to display them on the monitors that interest you. It should be obvious which screen produces the best result.
1. Run a magnifying glass over LCD screens to check for dead pixels.
2. Check how much you can enlarge a picture on the screen before individual pixels become visible.
3. Check the display’s angle of view. Although most of your work will involve looking directly at the screen, it can be handy to have a display that retains its accuracy for people who might view your image from one side when you’re working on it.
4. Check edge -to-edge sharpness and colour reproduction by opening an image file on the screen and moving it from side to side and top to bottom of the desktop. Watch for changes that occur in colours, brightness, contrast and sharpness. A good monitor should maintain consistency in all four parameters throughout the display area.
Note: you need to be very discerning when judging a monitor’s performance, as these changes may be very subtle. Make sure the display is evenly lit with no reflections off the screen to prevent you from seeing changes.
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