MegaVision Archival and Cultural Heritage Imaging

Digital imaging’s impact on the guardians of our cultural heritage treasures is profound. Digital imaging has opened new avenues of research, offered new opportunities of service, and permanently altered perspectives on preservation and conservation. Digital imaging, while unquestionably nascent, offers such compelling promise that even in its infancy it is being widely deployed and is beginning to deliver on some of its promises.  The many initiatives underway realize to varying degrees the promises; some would be well served with additional careful consideration of the goals.  In a rush to deploy, the digital image data that is collected often leaves much to be desired. The EurekaVision™ system has been developed to provide digital imaging capabilities of sufficient integrity and scope as to more than satisfy a range of goals which other imaging technologies not only do not, but in large measure cannot, contemplate.

The EurekaVision™ system integrates two previously disparate imaging capabilities: High- resolution photography and multi-spectral imaging. It captures very high resolution, high dynamic range, and highly repeatable digital images over a range of 12 or more spectral bands from the near ultra-violet to the near infra-red. The spectral bands are created not by using band pass filters to filter the light after it is reflected from the treasured object, but by using narrow-band LED illumination which subjects the treasure to only the light energy that is required to expose a highly sensitive, unfiltered monochrome sensor. This strategy results in orders of magnitude reduction in the light energy to which the treasure is exposed, and provides images of unprecedented resolution, registration, quality, and spectral content. Because the capture process is highly repeatable and because the captured image metadata is replete with not only artifact and collection specific data but also with capture specific detail, the captured images are documentary milestones that will be used not only in current conservation, preservation, scholarly, and reproduction  initiatives, but by those of future generations as well. The image datasets acquired by the EurekaVision™ technology become, in and of themselves, assets of scientific and historical value.

The EurekaVision™ multi-spectral imaging system is designed for preservation and scholarly studies of cultural objects, for studies of parchment, paper, papyrus, fabric, dyes, inks, paint, and other constituents of valuable objects, and for accurate color reproduction of cultural objects and art. The system includes an advanced large-format digital camera, a low-heat multi-spectral LED illumination system, operational software, and selected peripherals all operating as an efficient integrated system.

The EurekaVision™ system offers simplicity of design and operation with state-of-the-technology equipment for precisely controlled scene illumination, automated and controlled image collection, and efficient handling of captured image data and associated metadata. Image capture with a monochrome sensor yields unrivaled image quality. Illumination in distinct spectral bands with LED’s provides efficient high quality light with limited heat and yields precise spectral response for scientific studies and color reproduction.

Digital Camera: MegaVision E6

An integrated MegaVision Monochrome E6 39-megapixel back and camera (see note on monochrome image capture) is at the core of image capture. This system includes:

• Digital Back: MegaVision 39 megapixel E6 Monochrome
• Camera Body: 2X3 technical camera  with computer controlled aperture and shutter and a range of available optics ( for example, Schneider Apo Macro 120 mm f5.6.) Several specialty camera bodies available.
• Dynamic Range: 12 bits per channel: 14bit ACD
• File Size/wavelength: 78 Mbyte/color at 16 bits, 39 Mbyte/color at 8 bits.
• Capture Rate: One image frame per 3 seconds, subject to illumination constraints.
• CCD Array: 7216 x 5412 pixels, 6.8 micron pixel size.
• Equivalent Film Speed: Adjustable; 100, 200, & 400 ISO.
• Connectivity: IEEE 1394 Firewire 400
• PhotoShoot™ Software: Windows XP or Win2K.  Vista compatible but not recommended until future service pack release by Microsoft.

E6 description and specifications

Illumination: Eureka!Light™ LED Illumination System

A revolutionary Eureka!Light™ LED illumination system developed and integrated by Equipoise Imaging and MegaVision provides unprecedented opportunities in imaging and image quality. This system enables imaging in multiple distinct narrow spectral bands or combinations of spectral bands over a range of wavelengths from the near ultraviolet to the near infrared.

The lighting system is fully integrated with MegaVision’s PhotoShoot™ software and typically include light emitting diodes (LED’s) with up to 13 specific wavelengths, including:

Lighting Configuration
Each Eureka!Light™ panel is 36cm X 36cm X 8cm (14” X 14” X 3” ).  The panels mount with standard professional light stand mounting studs.  Inside each panel are modules that are configurable.  Each panel may be configured to include up to 13 different spectral bands with a total power of about 240 Watts.  For example, the panels may be configured with only 7 visible bands, or may additionally include several IR bands and a UV band.  Custom configurations are available to satisfy specific customer requirements.

The panels are powered and controlled via a power pack with an integrated USB Hub.  Up to 6 panels may be powered from a single power pack.  A single USB cable from the power pack to the computer enables PhotoShoot software to control multiple light panels. Panels may be tiled to form larger units.   PhotoShoot can simultaneously control up to 14 individual panels.

Software: MegaVision Photoshoot™

MegaVision's PhotoShoot™ digital image capture software is a comprehensive capture program designed to work with MegaVision's line of digital camera backs. PhotoShoot controls all aspects of image capture: shutter duration, aperture, light duration, light power, selected wavelength(s).   PhotoShoot  transfers captured images in uncompressed raw format from the camera directly into computer memory at about 20 megapixels/second.  A 12-band image capture typically requires less than one minute. PhotoShoot  immediately creates and places thumbnail previews into an "electronic proof sheet" on the computer monitor.  PhotoShoot’s tools for measuring and setting exposure enable precise adjustment of illumination to guarantee the very highest image quality over the entire spectral range.

PhotoShoot implements metadata support based upon EXIF and IPTC standards which may be customized to embed database information directly into the image files.  PhotoShoot enables automatic naming and organizing of captured images based on associated metadata.

PhotoShoot™ software controls the Eureka!LightTM LED panels and the digital shutter and aperture in an integrated fashion.  PhotoShoot also controls an optional color wheel should additional light modifications be desired (such as polarization or filtration to isolate fluorescence in concert with UV illumination).

Monochrome Image Capture
A MegaVision E Series camera with a Monochrome sensor is superior in several ways to cameras with color sensors.   Image capture with a monochrome sensor offers the following advantages:

1. A monochrome sensor doesn’t have residual artifacts left over from the color sensor's Bayer (or other) pattern filtration.
2. Without the Bayer filtration's ISO robbing filter factor, the mono back utilizes over twice the light from the scene, resulting in over twice the Signal-to-Noise ratio for a given illumination.
3. The need for interpolation (developing) and anti-aliasing filtration common to Bayer pattern dSLR devices is eliminated. Image resolution is increased, image purity is unrivaled, and image processing time is significantly reduced.
4. Fewer optical elements lie between the scene and the silicon.
5. Spectral confusion due to Bayer filter transmission overlap is eliminated, thereby reducing potential metameric failure and allowing improved display/printing flexibility.
6. When used with narrow-band LED illumination, there is no need to filter infra-red light from the sensor.  Eliminating the IR filter substantially increases camera sensitivity, further increasing S/N for a given illumination.

read more about Monochrome Image Capture

Color Capture With a Monochrome Sensor and LED Illumination
While the human color vision system is functionally tri-stimulus, our retinal spectral response curves can't be replicated by a simple set of 3 band-pass filters.  Somewhere in the range of 5-8 bands are required to get enough spectral information to make a good match to human vision.  Attempts to make practical systems utilizing multiple band capture with color filters between the scene and the sensor have not been successful (for reasons that can be readily appreciated).

By coming at the problem from a different angle, namely, creating the color bands at the source of the light (using LED's), the EurekaVision system solves the intractable practical problems. 

Capturing sufficient perfectly registered and highly repeatable spectral bands is an enabling technology for deploying semi-automated, high-quality color reproduction.  With tri-stimulus capture, color matching over a practical range of commonly encountered dyes, pigments, plastics, and other materials is sufficiently poor that individual, scene-specific color adjustments must be performed to obtain the desired quality.  This color-matching step is sufficiently time consuming and costly that it is practical to create high-quality color reproductions of only the most expensive originals.  The EurekaVision approach can dramatically reduce the amount of labor intensive post-processing of the image data and provide highly accurate color reproduction of a very wide range of difficult subjects. 

Multispectral Imaging Service
In the pursuit of various preservation, conservation, documentation, and reproduction goals, a cultural heritage institution may wish to apply high-resolution multi-spectral imaging techniques to selected objects in its collections.  Acquiring a system to accomplish this task may require a capital budget expenditure, additional staffing, staff training, and space allocations. 

read more about Multispectral Image Service