improving your image the ioe approach to quality assurance erpanet 23 - 25 june 02 victoria fenner,...
TRANSCRIPT
Images of England
• a new photographic survey of England’s
historic buildings, that will result in a digital
image library with up to 370,000 images
• the digital library will be accessible to all via
the internet, free of charge
Objectives
• Creating a digital image library for future generations, a ‘point in time’ record
• Making heritage information more widely available and accessible now
• Internet is delivery mechanism
Management
• £4.4 million project
• National Monuments Record, the public archive of English Heritage
Listed buildings
• Designated for: – architectural interest– historic interest– historical associations– group value– age and rarity
• 370,000 + separate ‘listings’
Listed Building System
• Created in a joint project between the
DCMS, English Heritage and Royal
Commission
• Source of indexing and architectural
descriptions for Images of England
• Not all buildings ….
The volunteers
• Army of volunteer photographers (>1,100 as of June 02)
• 35 mm cameras, colour negative film
• Providing photographic skills, local knowledge
The survey team
• Provide volunteers with film, a list of targets and supporting documents
• Brief them fully, including the standards expected
The defining image
• shows architectural character
• indicates function, where relevant
• shows something of a building’s context
• is a truthful image
• is of high technical quality
• provides visual information as well as being a ‘good picture’
Flowline
• Key relationship - link between the number of the listed build record, the film number and frame number
• Complex process, with 370,000 targets, 15,000 films and over 1,100 volunteers
• Essential to build in safety mechanisms
After photography
• Contractors process, print and scan
• IoE creates links between frames and films and the listed building records
Creation of digital originals
• Volunteers keep prints and negatives, digital originals are being created from 35 mm colour negative films
• Contractual specification of scanning requirements - resolution, colour depth and dynamic range, meta data etc.
Range of digital images
• Master set of images uncompressed TIFF files, archive only and available on demand
• Thumbnail, low, medium and high resolution JPEGs also created - first two only on website
Quality Assurance
• Digital images quality assured for:
– scan quality
– photographic quality
– establishing the right building has been photographed
Standards established
• Each image is given numerical score for scan quality and for photographic quality
• ‘Is it the right building’ - Pass or Fail
Scan quality
• Grades 1 and 2 only
• Grade 1 = pass = website
• Grade 2 = fail = re-scan or correct defect
Photographic quality
• How well does image meet the defining image criteria?
• Aims to be as objective as possible, to achieve a consistent standard
• Image QA guidelines drawn up
Defect codes
• Grade is determined by the presence and severity of ‘defects’
• Singly or in combination
• Grades 1, 2, 3 & 4
Photographic error codes
• Temporarily Obscured
• Differential Lighting
• Permanently Obscured
• Distorted• Cropped• Dull Image
• Framing/Composition
• Levelling
• Key Listed Features not visible
• Flare
• Vignetting
• Group Incomplete • Unidentified
• Camera Fault
• Focus
• Photographer’s Bits • Water/condensation on lens• Multiple Exposure
Variables at source
• Source photography– photographer skills– lighting and differential conditions
• Buildings themselves and locations
• Overcome by:– standards, guidelines, feedback, QA, review, audit
trail
Variables in digitisation process• Artefacts• High volume and high quality• Maintaining the workflow
– constant throughput vs. flexibility
• Overcome by:– standards, building quality into scanning
contract from outset, QA, change control