Brief History of Imaging Technology

Tim Vitale, v22, March 2012

The essay covers imaging technology over 5000 years: from polished stones through modern lenses; from light sensitive chemicals to acetate, nitrate and color film; includes discovering electricity through the first Fax, to analog video and digital still images. The preservation and storage of film and digital files is emphasized. The 5000-years-before-present time-line covers Lens History; Pre-Photography; Film Camera; B&W Photography; Color Photography; Digital Photography; Magnetic Media; Video Technology & Digital Printing Technology.

Historic Wallpaper Digital Remastered

Tim Vitale - June 2004, AIC BPG Session

PowerPoint presentation on the creation and mounting of digitally restored and printed wallpaper in the Yin Yu Tang House, at the Peabody Essex Museum. The project was a collaboration with Paul Messier and Staff who installed the wallpaper using at the Yin Yu Tang house using Rhoplex and heat.

ABSTRACT—Two very different pieces of installation art—Vito Acconci's Pornography in the Classroom (1975) and James Coleman's INITIALS (1993–94)—are analyzed using the protocols pioneered at the TechArchaeology Symposium. The Acconci work has two video channels, one with audio soundtrack and a series of slides. It is a conceptual work that was reformatted in 1998. James Coleman's INITIALS has one visual element—slides—with a synchronized audio channel output from four speakers. The differences are between a 25-year-old reformatted conceptual work (Acconci's) and a recent “structuralist's” work (Coleman's) that must be kept in its original format for the foreseeable future. This article is a result of TechArchaeology: A Symposium on Installation Art Preservation.

Related JAIC (Issue: 40/3) papers from the TechArcheology Workshop

ISSUE INTRODUCTION

Paul Messier: DARA BIRNBAUM'S TIANANMEN SQUARE: BREAK-IN TRANSMISSION: A CASE STUDY IN THE EXAMINATION, DOCUMENTATION, AND PRESERVATION OF A VIDEO-BASED INSTALLATION

Mitchell Hearns Bishop: EVOLVING EXEMPLARY PLURALISM: STEVE MCQUEEN'S DEADPAN AND EIJA-LIISA AHTILA'S ANNE, AKI AND GOD—TWO CASE STUDIES FOR CONSERVING TECHNOLOGY-BASED INSTALLATION ART

William Real: TOWARD GUIDELINES FOR PRACTICE IN THE PRESERVATION AND DOCUMENTATION OF TECHNOLOGY-BASED INSTALLATION ART

Pip Laurenson: DEVELOPING STRATEGIES FOR THE CONSERVATION OF INSTALLATIONS INCORPORATING TIME-BASED MEDIA WITH REFERENCE TO GARY HILL'S BETWEEN CINEMA AND A HARD PLACE

Cold Storage of Cultural Artifacts

Tim Vitale, v17j, revised May 2008

An extensive review is presented with the inclusion of new work on the cold storage of cultural materials, including film and video tape. The options of walk in vault, portable refrigerated container and a frozen storage vault are examined and compared.  Passive and active vaults are explained.  Cost estimates of the options are provided based recent data. Cold storage is the only method of halting the chemical deterioration of nitrate and acetate film base, and, the fading of color film.  The common recommenced range for storage of all cultural material is 70°F +/- 10°F and 50% RH +/- 10% RH (room conditions). Storage in warm room at 85°F and 60% RH will decrease the average life of an artifact by about 25%; storage at lower temperatures and relative humidity is desirable. Storage in a “cool or cold” room (60° and 40° F respectively) will increase the average life of an artifact 4-20 times.  Cold storage of film at frozen (-4° to -20° F) conditions will prolong its life by 400-30,000 times, depending on the exact conditions.  The actual lifetime depends on the current state of deterioration; methods of making this evaluation are provided.

History, Science and Storage of Cellulose Acetate Film Base

Tim Vitale, v16b, revised June 2009

Report on cellulose acetate film. Explains the history and science of how the film base was developed and used for still and motion picture applications. The identification of deterioration faults and a scale for determining condition states is included. The chemistry of cellulose acetate and the deterioration process is explained. Recommendations for storage, cold storage and use are reviewed. Cold storage is the only tool to halt the deterioration process.

History, Science, Preservation and Storage of Cellulose Nitrate Film

Tim Vitale, v26, revised June 2009

This report on cellulose nitrate film is a companion to the History, Science and Storage of Cellulose Acetate Film Base above. The history and science of how the nitrate film was developed and used for still and motion picture applications is explained. Identification of deterioration faults is presented along with a scale for determining condition states. The chemistry of cellulose nitrate base, the deterioration process and combustion products of nitrate fires are explained.  Recommendations for storage, cold storage and use are presented. Cellulose nitrate film base will degrade in a minimum of 50-60 years, but new predictions suggest that it could last up 500 years. Cold storage is the only tool to halt deterioration.

Estimating the Resolution of Historic Film Images: Using the Resolving Power Equation (RPE) and Estimates of Lens Quality

Tim Vitale, v9 - revised November 2009

Determining the resolution of an image in a specific piece of modern film has become common when the film type and taking-lens are known. Doing the same for images made before 1940 is complicated by the lack of information on native film resolution and lens quality. A method of making an estimate is provided and explained. It is recommended that the film be scanned at twice that resolution, to allow for the Nyquist sampling rate.

Film Grain, Resolution and Fundamental Film Particles

Tim Vitale, v24 - revised October 2009

Review of film grain and fundamental particles in film. The effects of film grain and fundamental image particles on image noise, image resolution and digital scanning are examined. Film gain is image noise (lack of uniformity) that appears to have a shape, but under magnification, this is not the case. Sources of film grain such as color dye clouds and fundamental silver particles are examined and explained.  Film grain is not a fundamental film particle that can be resolved at a finite magnification. RMS Granularity, Print Grain Index and measuring film grain is explored.  Methods of eliminating film grain are examined, reviewed and compared when images are scanned.

Digital Image File Formats and their Storage: TIFF, JPEG & JPEG2000

Tim Vitale v20 - updated April 2010

Storage of image information is crucial for its long-term preservation.  Although digital images can be stored indefinitely without deterioration, they can be lost.  A digital file can be permanently “lost” if it is stored without regard for basic computer technology or on inappropriate storage media.  The recommended storage medium is the harddrive (HDD), which is viable for 5-10 years; see Section 6 “Storage” pages 35-39 for details.  Although a HD can fail, it is usually backed up on another HD, or the files are stored in an internally redundant RAID array (mode 1 or 6, not 5).  Optical media (CDR, DVD-R) fail without warning (3-25 yrs) and their (disk) readers probably won’t be available in 15-20 yrs.

Digital Imaging in Conservation: Cameras (dSLR)

Tim Vitale, v6/v12 (long version) with short version in the January 2005 AICNews

Still has relevant information that can be used today.

Digital Imaging in Conservation: File Storage

Tim Vitale, v28 (long version) with short version in the January 2006 AICNews

Information as relevant today as 5 years ago, except the HDD are bigger and cost even less.

Lens MTF Data and Graphs - An Excel Spreadsheet

Tim Vitale, v13 2007 (this is not a PDF, but a rather a ZIP'd spreadsheet)

Click on image to the left to download a Zip'd version of v14a. To download the uncompressed *.xlsx spreadsheet click on the file name <lens_mtf_data_graphs_v13.xlsx> and right click on <Save AS>. To use this file, it must be opened in a spreadsheet program such as MS Excel.

Affects of Lens Quality on Image Resolution - DRAFT

Tim Vitale, v3a DRAFT DOCUMENT (July 2010)

This document was created to explain the difference in image quality between cameras (imaging devices) found in mobile phones and more traditional dSLR, medium-format SLR and large-format scanback (BetterLight) type cameras. The issues are: (1) pixel size, (2) Bayer Pattern (3) extensive software processing of distorted image files and (4) unknowns. The problem is comparing different systems using metric that span both imaging domains.

Light Levels in Modern Flatbed Scanners

Timothy Vitale, 1997, Originally Published by RLG DigiNews

Introduction
It has been said in some quarters that scanning is equivalent to exposing an object to a day's, or a year's worth of sunlight. This article examines that claim,and will show that not only is this not true, it may well be impossible.
Scanning an image on a flatbed scanner involves passing a sensing array (Charged Couple Device, CCD) along an object resting face down on a glass platen. The array has a light source attached. Today these sources are usually of the cold-cathode type (1) because of their color characteristics and cooler operating temperature. The method is similar to that of a photocopy machine. This has caused a misinterpretation of the scanning process. Until recently, copy machines used very strong light to produce an image on a relatively light-insensitive coated drum, which resulted in toner being deposited onto paper. The amount of light needed was dictated by the low sensitivity of the coating on the copy transfer drum. Today's CCDs have sensitivities between 0.1 and 0.001 lux. (2) This means that a CCD does not need blazingly bright light to achieve its goal. Scanner lamps have evolved for a technology with greater light sensitivity.

RECENT RESEARCH

Testing Still-Image File Compression using JPEG2000, JPEG & TIFF-LZW

Tim Vitale 2007 to 2010,

Link to: http://videopreservation.conservation-us.org/tjv/index.html

Summary of J2K Results: The images used for these tests are very high quality, and the files are large. The analysis procedure was particularly taxing on any changes in RGB numeric values held for each pixel within a TIFF image file. While the image processing (image enhancements) showed changes in RGB numeric color values, the number of unique colors as analyzed in Corel Paint Shop Pro X2 was revealing. The change in actual number of colors, shows that the actual RGB values are changed in the lossy mode.

The lossless compression (LL) process reduces file size between 37% (photographic image) and 79%. Note that the latter was for a drawing created in Photoshop without any photographic component. The lack of detail in the "difference" image (gray square on left) shows that no change in RGB values were produced. The fact that the image is gray is the result of the "em3" enhancement process, which moves the blacks (showing absolutely no change) to gray, so that small changes could be seen if they were present. When a gray image is shown, no changes were recorded.

The lossy (lo) compression process generally degrades photographic images, but appears not to effect 16-bit non-photographic images, that is, images made wholly in Photoshop using the paint, draw and airbrush functions.

Summary of JPEG Results: The images used for these tests are very high quality and the files are large. The analysis procedure was particularly taxing on any changes in RGB numeric values, held for each pixel within a TIFF [host] image file. While the image processing (image enhancements) showed changes in RGB numeric color values, the number of unique colors as analyzed in Corel Paint Shop Pro X2 was revealing. The change in actual number of colors, shows that the actual RGB values are changed in the lossy mode.

All levels of JPEG compression tested showed some degree of change in the RGB numeric values. The darker the images on the left show a lesser degree of change as a result of compression. The lighter the "difference" image (on the left) the more change in the RGB values as a result of JPEG compression.

ABSTRACT—Fundamental physical and mechanical properties of albumen photographs were studied with the goal of explaining the tendency for pre-existing cracks in the albumen layer to increase in number and width when exposed to water. Samples were taken from the following materials: historical 19th-century albumen prints, unsized cotton paper, albumen prints made by the authors for the purpose of the study, albumen/paper composites, and “bars” made by casting albumen in silicone grease troughs. The samples were subjected to a variety of tests, including stress-strain analysis, ultrasonic impediometry, and measuring before, during, and after exposure to humidity. The various materials that make up an albumen photograph respond differently to changes in relative humidity, leading to problems between the components. Care should be taken when treating albumen prints with either water or water vapor, and the conditions under which the prints are stored should be carefully considered.