What Is ISF Calibration?
By William Norman
ISF calibration helps home video displays deliver the best possible image quality. Most televisions and home video systems display wildly inaccurate images when first installed. According to Sound and Vision, manufacturers deliberately boost the brightness, contrast and color settings to unnaturally high levels to show these devices off amidst the fluorescent glare of an electronics showroom. Once the display enters a home theater or living room environment, calibration corrects errors such as distorted picture geometry, artificially sharp edges and overemphasized red tones.
The Imaging Science Foundation, or ISF, has helped home theater owners and electronics manufacturers understand and make use of proper image calibration since its founding in 1994, according to Sound and Vision. ISF-certified calibration technicians specialize in adjusting the levels of a projector or television to its environment by balancing the color, contrast and brightness setting both against the room lighting and against each other. Purchasers of home theater gear might find that the electronics store they bought the equipment from offers its own ISF-certified technician. Other ISF-certified technicians work independently.
Types and Costs
The amount of money a home theater owner will spend on an ISF calibration depends of the extent of the service and the type of video device. The ISF recommends that calibration technicians charge $325 for front-projector systems, $275 for rear-projection televisions and $275 for standard CRT-tube or flat-screen televisions, as of June 2010. These entry-level rates include calibration of the user-serviceable image control levels and the the unit’s gray scale response. Advanced calibration techniques applied to a deluxe front-projector setup can cost $1,000 or more, as of June 2010. In remote areas, the purchaser might pay a travel fee as well.
Tools and Measurements
The calibration technician uses specific tools for measuring and adjusting the various factors that influence image quality. Test pattern generators such as the Video Essentials or the Avia Guide to Home Theater DVDs run the set through a series of tests so the technician can gauge and adjust each video level. Some technicians prefer to use an external signal generating device that makes the test pattern DVD unnecessary, especially when calibrating a high-definition display.
After selecting the most accurate image preset the user menu offers as a starting point, ISF calibrators adjust the delicate balance between brightness, which determines the image’s maximum black level, and contrast, which determines its maximum white level. The calibrator then adjusts color and tint using industry-standard color bars while looking through blue, green and red filters. Finally the calibrator adjust the gray scale from a test image of gray rectangles.
Home theater owners will note dramatic changes in picture quality following a proper, comprehensive ISF adjustment. At first the image may seem inappropriately muted or dark, but in fact these new levels represent the image as the filmmakers intended it for viewing in the dimly-lit environment of a movie theater. Once viewers get used to the calibrated image they will notice the lesser quality of an uncalibrated system.