The Zone System - Advanced Imaging Conference
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The Zone System - Advanced Imaging Conference

Zone System for CCDAdvanced ImagingConferenceRon Wodaski

Dow Chemical Co. v. Mahlum, 114 Nev. 1468, 970 P.2d 98 (Nev., 1998)second version of the study, entitled "Five Silicone Materials," omitted all references to the sixthcompound and its effects. The second version also explained that initial testing had suggested adepression in the number of leukocytes (white blood cells) in all female rats over a period of 90 days, butthat subsequent work on control animals showed that silicone was not the cause of the decrease.In 1959, Dow Corning established the non-profit Center for Aid to Medical Research, whichprovided the medical community with medical products and research regarding the uses of silicone formedical applications. In the early 1960s, Dr. Thomas Cronin, a plastic surgeon and researcher fromBaylor University, approached Dow Corning about the possibility of using silicones in breast implants. In1962, Dow Corning commenced clinical trials on silicone breast implants. Dow Corning sold $93,000.00worth of breast implants in 1962. 2In 1964, Dow Corning formed its Medical Products Division. Also in 1964, Dow Chemical acquireda substantial interest in Gruppo Lepetit, an Italian pharmaceutical company that had, in some foreigncountries, an exclusive distribution agreement with Dow Corning to market Dow Corning's medical line,including its breast implants. Lepetit sold Dow Corning breast implants outside the United Statesthroughout Europe, South America, and Australia.Page 105From its inception, Dow Corning has enjoyed physical proximity with Dow Chemical, being locatedjust "across the road and down the way" in Midland, Michigan. In 1965, Dow Corning created aBioscience Research Department to explore the potential biological activities of organosiliconcompounds. The department was housed in the same building as Dow Chemical's toxicology and researchlaboratories until 1970. Until 1968, Dow Corning lacked its own toxicology laboratory and staff andrelied on outside contract laboratories, such as Dow Chemical, for toxicological testing and information.Dow Corning scientists often sought input from Dr. Rowe and other Dow Chemical scientists regardingsilicone technology and toxicological effects. In 1968, Dow Corning established its own toxicologylaboratory, but for the first two years, it shared the same building as Dow Chemical's toxicologylaboratory. Dow Corning continued thereafter to share laboratory facilities and animals with DowChemical, and its scientists continued to consult with Dow Chemical personnel regarding toxicologicalresearch. From 1968 until 1973, Dow Corning's new toxicology laboratory and staff were headed by aformer Dow Chemical toxicologist, Kenneth Olson. In 1973, Olson returned to work for Dow Chemical;Olson testified that in his capacity as the chief toxicologist for Dow Corning, he likely knew that DowCorning's breast implants contained silicone fluid as a component.Dow Chemical was not the sole testing facility doing research for Dow Corning. Between 1964 and1976, Dow Corning commissioned outside laboratories, often those recommended by Dow Chemical, toconduct animal testing and long-term studies on breast implants and other silicone products. In 1967,Dow Corning entered into a joint research and development agreement with Dow Chemical "relating tothe physiological effects resulting from ingestion or injection into the systems of animals or men ofparticular physiologically active silicones." The two companies also agreed to "jointly share the costs and... share the profits and losses of any commercialization."Also in 1967, Dow Corning implemented a two-year study on miniature Silastic breast implants indogs, conducted by an outside laboratory, the Food and Drug Research Laboratories, Incorporated("FDRL"). An internal Dow Corning memorandum in 1967 referenced that Dr. Rowe was one of theconsultants who recommended this study. Although the study appears to have been principally designedby FDRL, part of the testing protocol may have involved Dr. Rowe.- 3 -

What Histogram Changes DoStarting HistogramCurves tool expands dim, contracts brightAnother Curves – Dim expanded furtherAnother Curves – Final histogramHistogram changes increase the number ofslots available for dim portions of the image

Zones and the HistogramDark zoneDim zoneMiddle zoneBright zoneWhite pointGradientPseudo white pointBlack pointLow S/NHigh S/N

Why Zones WorkS/N = Certainty/Uncertainty• Signal = Certainty• Noise = Uncertainty• Noise hides subtle details because it makesbrightness values variable• Noise limits processing choices• S/N correlates to brightness– Dim areas have poor S/N– Brighter areas have better S/NS/N level dictates processing choices

Zones Based on S/NUse brightness to identify S/N level:• Dark zone– Below the black point (eliminate)• Dim zone– Darkest details you want to reveal (smooth)• Middle zone– The bulk of the data (histogram only)• Bright zone– Stars, galaxy cores, bright nebulosity (sharpen)

NGC 1491The Zones Revealed

Dark Zone Defined• Definition: The portion of the imagethat is so dominated by noise that it isuseless for presentation in the finalimage.• Processing: Eliminate with black point• Set the black point just below the topof the Dark Zone.

Why Eliminate Dark Zone?Blatant disregard for noiseBlack point adjusted for noise

Dark Zone Boundary• The Dark Zone boundary is determined by thetotal noise.• Minimize Dark Zone by minimizing net noise:– Long total exposure time (think hours, not minutes)– Long enough individual exposures (minimizecontribution of read noise whenever possible)– Dark skies– Excellent focus– Fastidious application of dark/flat/bias with manyframes of each type (8 or more recommended)

Dim Zone Defined• Definition: The noisy but salvageableportion of the image – dim details.• Processing: Smoothing• The Dim Zone has poorest S/N, butgets the heaviest histogram boost.

Middle Zone Defined• Definition: Just like the name says – thestuff in the middle.• Processing:– Not noisy enough to need much smoothing, ifany;– S/N not good enough to encouragesharpening• The Middle Zone doesn’t get a lot ofprocessing other than histogram changes

Bright Zone Defined• Definition: The areas of the image withthe best signal to noise ratio.• Processing: Sharpening/Deconvolution• High S/N level means few artifactsfrom processing.• You can increase the portion of theimage in the bright zone by using alonger total exposure time.

Photoshop summary• Check black and white points (Levels)• Several iterations of Curves– Use standard curve– Refine black point after every Curve• Find brightness of dimmest details• Boost dimmest details as much as noiseallows• Balance 256 brightness levels betweenzones using Curves (interzone contrast)• Make micro-contrast adjustments to revealstructure (intrazone contrast)• Create stars layer and manipulate/clean up• Add RGB layer, correct color

Photoshop Demonstration

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