Understanding Image Quality Choosing the Right Resolution and Format

Choosing the Right Resolution and Format

Resolution determines how much information is captured when an image is digitised, while file formats determine how that imagery is delivered. Understanding both will help you choose the most appropriate product for your project.

Understanding Image Resolution

Resolution is measured in pixels per inch (ppi) and describes how much information is captured when an image is digitised.

Higher resolutions capture more information from the analogue photograph. However, a higher resolution does not automatically mean more visible detail, as image quality is ultimately limited by the source material.

Common NCAP Resolutions and Typical Use
72 ppi Research copies
1200 ppi Standard image delivery
1270 ppi Photogrametric scanning resolution
2000 ppi Photogrametric scanning resolution

For more information on how image quality is affected by source material, image scale and flying height, see our Image Quality Factors and Scale & Flying Height guides.

Understanding File Formats

NCAP imagery is primarily supplied in two formats.

JPEG - Typically supplied for:

  • Research copies
  • Already digitised imagery purchased through the online catalogue

TIFF - Typically supplied for:

  • Scan on Demand imagery
  • Professional digitisation projects
Resolution & Format Guide
Research Copy 72 ppi, JPEG Image identification and archive research
Already Digitised Imagery 1200 ppi, JPEG(6) Standard purchase through the online catalogue
Scan on Demand Imagery 1200 ppi*, TIFF Standard purchase via Scan on Demand service
Digital Format Upgrade 1200 ppi, TIFF Professional review and reporting
Second World War Imagery 1200 ppi, TIFF Maximum achievable quality from wartime photography
Photogrametric / Modern Imagery 1270, 2000 ppi*, TIFF Specialist technical applications

*Availability depends on the collection and original source material.

Please note that some born-digital survey collections were originally created at lower resolutions. In these cases, imagery will be supplied at the highest resolution available from the original source material.

IN THIS SECTION

2 purple-gloved hands prise apart a stack of slightly curled photographic prints.

Image Quality Factors

Explore the factors that influence image quality, from the condition of the original photograph to scanning methods and image processing. Learn why some images contain more visible detail than others.

A colour aerial photo of islands surrounded by a deep blue sea. There is one big island left of centre and a small one to the right. The islands have green grass and a mix of rocky and sandy shores. The sea is light blue over the sand.

Scale and Flying Height

Discover how aircraft flying height and photograph scale influence the level of detail visible within an image. Understanding these relationships will help you assess what information can realistically be identified and interpreted.

A black and white aerial photomap of a town surrounded by an irregular grid of black and white fields. The photomap is annotated with place names – including Stargard, the name of the town – and is overlaid with numbered map grid squares.

Second World War Imagery

Second World War aerial photography remains one of NCAP's most heavily used collections. Explore its unique characteristics, limitations and strengths to better understand image quality and set realistic expectations for available detail.

A purple gloved hand reaches in from the left. They are using a brush with a white handle to brush the surface of a black and white photographic print towards the nozzle of a black vacuum cleaner. There are other images and boxes on the table.

Pre-Digitisation Preservation

Learn how NCAP prepares historic films and prints for digitisation, helping to protect original materials while producing the highest-quality digital images possible.

Two hands wearing grey gloves hold a slim cardboard box. They appear to be moving the box, and the bundle of boxes piled beneath it, on to the white shelving behind.

Understanding Collection Coverage

Learn why aerial photography coverage varies between locations, periods and collections, and how this can influence the imagery available for your project.