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All display monitors function to display information to the user. Typically monitors will utilize a display device, intricate circuitry, a robust casing and power supply to adequately provide a display output for the user. While computers and their monitors were originally developed for processing data, their usefulness eventually expanded to television receivers and other entertainments devices that we commonly use today. To measure the quality of a monitor’s display output, numerous parameters must be measured, some of which include:
- Aspect ratio
- Viewable image size
- Display resolution
- Contrast ratio
- Refresh rate
- Pixel size
- Electromagnetic fields
- Stray light levels1
To evaluate these important aspects of monitor display output, industries can employ a variety of analytical instrumentation that can be used to test and calibrate the displays on computers, smartphones, tablets, televisions, cars pedometers, jet engine designs, surgical diagnostic tools, military applications and much more. In addition to providing quality control information during the use of these products, these techniques can also be used within the display panel production line, provide comparison between manufacturers and ensure that health and safety specifications are being met.. Some examples of these measurement devices include:
Spectroradiometers for Display Output Measurement
What is a Spectroradiometer?
A spectroradiometer is capable of measuring the spectral radiance or irradiance across various spectral ranges. Equipped with an optical measuring and targeting system, of which includes a light that typically measures within the wavelength range of 380-780 nm, a spectroradiometer is a highly accurate instrument that is used in research and development laboratories.
Spectroradiometers and Output Displays
When used for the purposes of characterizing a given monitor’s display output, a spectroradiometer is capable of measuring the viewing angles, which reflects the maximum angle at which the monitor can be viewed without causing any excessive degradation of the image’s quality, of a display as well as determine both gamma and contrast, which provides information on the ratio of luminosity of the brightest color (white) as compared to that of the darkest color (black), ratios2.
Some spectroradiometers that are currently available and widely used for measuring monitor output displays include:
- UPRtek Desktop Spectroradiometer – MD100N
- Konica Minolta Spectroradiometers:
Photometers for Display Output Measurement
What is a Photometer?
The working principle of a photometer is to measure the levels of electromagnetic radiation that directly corresponds to the human eye’s response. Note that any response provided by the human eye can be affected by the wavelength of the radiation, as well as interpersonal differences. To provide a consistent measurement base for photometry-based instruments, the function of V(l), which applies for typical day-time light levels, and V’(l), which is used to describe low lighting levels3. Therefore, photometers will only consider visible light that exhibits a wavelength range of 380-780 nm.
Photometers and Output Displays
When utilized for measuring display output levels, photometers are useful tools capable of comparing ambient illumination to video screen brightness and determining the uniformity of the image’s quality displayed across the screen. Some photometers that are currently available and widely used for measuring monitor output displays include:
- M&A Instruments Inc. – SM208 Screen Brightness Meter
- Gamma Scientific Photometers
- Quantum PhotoMeters
Colorimeters for Display Output Measurement
What is a Colorimeter?
Typically utilized for chemical analysis procedures, colorimeters utilize an internal light source that directly shines the light onto the surface of a sample. As this this light bounces off of the object and returns to the device, it passes through three different filters of red, green and blue, all of which will distill tri-stimulus (RGB) values that are used to represent how human eyes visualize the color as shown on the object4.
Colorimeter and Output Displays
Within the technology world, colorimeters are often used to calibrate computer screens to ensure that the correct color is being presented on the computer screen. Some colorimeters that are currently available and widely used for measuring monitor output displays include:
- “Display Measurement and Evaluation” – National Physical Laboratory
- “What is the difference between radiometers, spectrometers and spectroradiometers?” – Konica Minolta
- “Principles of Photometry” – National Physical Laboratory
- “Colorimeter vs. Spectrophotometer” – X-Rite Pantone