Multiple Light Sources - Comments of Christopher Boston Director, Software Solutions at Datacolor http://www.linkedin.com/in/christopherboston
On 03/04/09 6:37 AM, Christopher Boston wrote:
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The multitude of illuminants is an unfortunate fact of life in this industry; I have personally added over 20 new illuminants to Datacolor software over the years.
Having a standard illuminant SPD is nice from a consistency perspective, but to be of real value, it needs to be realizable using standard phosphors, otherwise you will always have a battle between suppliers that match the standard under the target illuminant perfectly but whose samples are flaring in the wrong direction when viewed under the light box.
To make matters worse, with narrow band illuminants, some of the dominant wavelengths have a very narrow bandwidth, for example I recall TL84 having significant power at only 3 or 4nm around its dominant wavelength. This makes the lamp nice and cheap to make, but it means that getting a non-metameric match is very difficult. particularly when the illuminant and measurement are being integrated to 10 or 20nm. With modern computers and electronic communication, the industry could significantly reduce the number of rejections by increasing measurement resolutions to 5nm or even smaller. the days of hand-keying data should be long behind us.
Depending on the phosphors used, the difference between a 3000K lamp and a 3500K lamp could be huge; indeed the difference between two alternative 3000K lamps could be highly visible when evaluating certain colors. Consider a full spectrum tungsten bulb heated to 3000K compared with a triband 3000K fluorescent tube for an extreme example.
Illuminants will continue to be a source of contention I'm sure, but remember that from the consumer's perspective, they want products that coordinate together non-metamerically in daylight and their home or favorite restaurant lighting. -- I don't recall seeing U3000 in any of my friends homes!
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- Jayakumar ( JK)
- Madras, India
- A textile technologist, chemist to be more precise. Have taken up responsibilities with AATCC and ASTM International to provide technical and support services to members and member prospects. Involved in QA systems implementation for Textile producers. Work with some of the top rated technicians in the world. We are Rated very highly Globally. I share my knowledge and experience ( Episteme and Techne)with the industry. Conduct Training programs for AATCC and ASTM Intl. In addition design and deliver tailor made programs and deliver lectures. Love to drive in search of desolate and exotic locations, where the air is clean , water in pure and nature is still natural. Ironically I Love gadgets and gizmo's and experimenting with new hardware and software. Life is not perfect , but it is interesting. Imperfections make life worth living. A perfect system is no challenge to the body , mind and soul.
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