SMART III - Video Calibration Toolkit

Steve Smallcombe's SMARTAVTWEAKS site


SMART III for DLP-based Projectors

While SMART was developed using an LCD-based projector, the SONY 10HT, its usefulness extends to many other types of projectors as well. In fact, SMART III is particularly well suited for use with DLP projectors where the high dynamic range of SMART’s light meter-based detector is a very good match for the high contrast ratios associated with DLP projectors.

So say you have a projector with a contrast ratio of 2000:1. What measurement range do you need in the detector to accurately measure the contrast ratio or the low-level color balance? Is a detector with a measurement range of a few thousand to one good enough? Not really. Let’s say that the resolution or detection limit of the detector is one unit. If you make measurements, e.g. of a black level that are only a few units, changes, e.g. from 2 to 3, can swing the measurement of contrast ratio by 50%! Clearly for accurate measurements, all light levels should be measured well above the minimum possible reading for that detector, ideally by a factor of 100 or more.

Unfortunately because of limited dynamic range, most all devices meant to measure color cannot accurately measure a contrast ratio of more than a few hundred to one, or color balance at low IRE levels with modern projectors. Detector linearity can also be a problem with many color detectors at low light levels and small tweaks can sometime produce surprising (and unbelievable) results.

As the contrast ratio performance of projectors has steadily improved over the years, this problem has become more acute. SMART started as a very simple do-it-yourself approach using photocells and colored filters. This worked well with the 10HT, but as I started looking at projectors with higher contrast ratios, and realized the importance of accurately measuring low-level color balance, SMART needed something better. It was actually Bill Cushman that recommended that I switch to the AEMC meter that we now use for SMART III, as it has a dynamic range of 2 million to 1. (The Extech meter we also use is equally good.) These meters are very linear and one can accurately measure contrast ratios of many thousand to 1 with very good accuracy, as well as the color balance at IRE 0! (You may have noticed that SGHT now uses light meters to measure contrast ratios as well rather than relying on their professional color meters.)
This high dynamic range and linearity is also very good for measuring gamma and gamma tracking, another important characteristic of projectors that is critical in getting a accurate image, but again poorly measured using other color measurement systems, especially gamma tracking at low light levels.

For these reasons I have just introduced a new “DLP” version of SMART 1.2 in which I have incorporated improved gamma tracking calculations and the changes necessary to deal with the different spectral characteristics found with typical DLP bulbs and color wheels. These changes are based on the DLP projectors that I have either reviewed or measured using SMART. While previous version of SMART worked well with DLP, these changes should make SMART work even better with DLP-based projectors.

Home Page

Introduction to how SMART works

Frequently Asked Questions about SMART

Here is what's new is SMART III version 1.2

The Dummies Guide explains the SMART process in a non-technical way

Buy SMART III at EnhancedHT - your exclusive source for all SMART products

Not sure you are ready to try SMART yourself? Have a certified SMART person do the calibration for you

Having trouble? Learn the most common mistakes people make using SMART

Read about using bias lights to improve perceived black levels.

Here are some additional tips for the SONY projectors and solution to common problems.

Copyright 2001-2005 Steve Smallcombe