The Model 820 Video Photometer measures the absolute brightness of any size sample or scene and provides quantitative data in fL or cd/m2. The 820 photometer is used to measure the performance of lamps, LEDs, backlit panels, control switches, etc. It also quantifies reflectance, micro pitting, reflective and transmissive haze, and other appearance characteristics.
The 820 photometer generates a 640 x 480-pixel image digitized to 256 gray levels. This offers a light measurement capability equivalent to 307,000 light meters. The lower cost 820 utilizes an interlaced camera and TRICOR's Eyeppearance® software (a Windows compatible PC-based software system) to provide analysis tools used to establish photometric levels for an image.
A user-friendly Windows® interface offers many menu options for analyzing the acquired gray scale image; however, the real potential of Eyeppearance® is realized when a calibration transform file is loaded for the image. The calibration transform translates the relative gray levels into absolute radiometric levels. Pixel radiance levels and histogram distributions are given in photopic units.Some Typical Applications include
Menu options, such as the Enhance option, provide a close coupling of the image data and the histogram distribution. The image is highlighted in green for a given section of the histogram. The user can use the mouse to quickly change the highlighted radiance levels in bandwidth and position on the histogram distribution. Also, false coloring can be applied to the image, allowing the user to readily see those areas below, above, and within the user-specified tolerance band. Quantitative values associated with the highlighted area(s) are then displayed on the PC screen.
Another powerful feature of Eyeppearance® is its ability to define up to 254 regions of interest. Each region of interest may be any region as outlined by the user using the mouse. From this region an active subset can be selected, which establishes a new histogram distribution and limits image analysis to this active region only.
|Receptor||Silicon CCD filtered to closely match the CIE relative photopic luminosity response|
|Calibration||System supplied with one set of calibration curves (one curve for each of the eight shutter speeds at one lens f/stop)|
|Light Measurement Scales Light meter||
|Analysis Capabilities (partial listing)||
|Field of View||
|Luminance Units||cd/m2 or fL selectable; calibration values in memory automatically converted for user display|
|Light Measurement Ranges||
|Accuracy||±4% of measured value (Measuring conditions: subject: standard illuminant A; ambient temperature: 20° to 30° C (68° to 86° F)|
|Short-term Repeatability||±0.4% (Measuring subject: standard illuminant A)|
|Resultant Image||640 x 480 x 8 bits resolution (256 gray levels)|
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