Managing digital images in your organisation
This guide will walk you through best practices for managing digital images, including preparation, capture, storage, and disposal.
Why you may need to manage digital images
Images often provide valuable evidence that supports other business records, especially in legal or investigative situations.
There are many reasons you might need to manage digital images in your organisation.
For example:
- Workplace safety: Inspectors at WorkCover NSW might take photos of an accident scene to support investigation reports.
- Asset management: The NSW National Parks and Wildlife Service captures images of parks to help manage their assets.
- Law enforcement: Service NSW uses images from speed cameras, and local councils manage photos of parking violations for issuing fines.
- Business reporting: You might simply need images to illustrate business events for an annual report or your website.
Digital images can be created easily, shared quickly, and take up considerable storage space. They are also vulnerable to errors or misuse, so it’s important to handle them carefully, especially when they are used as legal evidence.
Key considerations for managing digital images
Managing digital images requires attention to detail. If your organisation uses digital images for official records, you must plan for the capture, storage, and use of these files. Here are key things to consider:
Before creating any digital images, (for example through taking photographs, graphic design or screenshots), ensure you have clear procedures in place. This includes deciding the purpose of the image, the equipment you’ll use, metadata required for identification, rights management and the quality, format and resolution in which you’ll save the image.
If there is an important evidential need to capture the images you will need to consider the appropriateness of implementing even stricter measures to ensure that their integrity will be safeguarded.
This may include:
- training and assessing staff for competency regarding the organisation’s standard operating procedures, implementing imaging standards and relevant imaging technologies
- authorising staff members to capture images, with roles written into their job descriptions
- establishing a quality management program
- conducting validation tests1 on the system to ensure its suitability for the intended purpose, including determining accuracy and precision requirements for imaging equipment, and a calibration/verification program
- ensuring equipment is checked for accuracy before every use
- adding levels of protection or verification to images such as hash verification or encryption2
- ensuring that appropriate levels of documentation will be captured in audit trails.3
Working with primary, original, and working images: Your organisation may need to save multiple versions of an image.
Consider if primary, original, and/or working images need to be used. Primary images are created when the image is initially captured (for instance, a photo is captured on a memory card in a digital camera), while original images are exact copies of the primary image (for instance, created when copying an image from a memory card onto a hard drive). Working images are edited versions used for specific purposes like web display.
Original images should be retained for certain types of images such as those which will, or may be, used as evidence in court, with long term retention requirements, or required as State archives. The integrity of original images must be maintained.
When choosing a camera or capture tools, consider the purpose of the image. TIFF, PNG and JPG files are recommended as suitable formats. Avoid using proprietary formats that may become outdated. If a proprietary format is used (e.g. for some level of additional functionality) it should be converted to an open standard format before being stored.4
Note: Digital SLR cameras offer a native or RAW format, and smartphones similarly have the ability to capture photos in a native or RAW format. RAW format is not a single file type, but the name given to any image file containing unprocessed data as captured by the digital sensor. Most camera manufacturers have created their own unique RAW formats. Native RAW files are encrypted, and the formats are largely undocumented.5 State Records NSW does not recommend you retain images in RAW format as there is not a non-proprietary standard format. This could threaten the longevity and continued readability of images stored in RAW format.
A key to ensuring that your images are usable and accessible is to include sufficient metadata with the images. Organisational procedures for managing digital images should include a metadata schema. This may include:
- descriptive metadata such as the title and creator of the image
- workflow metadata regarding its capture
- processing and quality assurance
- source metadata regarding the Original and information relating to Working images
- digital rights management metadata such as copyright, sales and usage information
- Implicit metadata may be deduced from the file itself, such as file size, type and date created.
Where possible, metadata should use standardised vocabulary, syntax and should be entered at the time of creation. Most image collections seek to comply with Dublin Core or the Australian Government Locator Service (AS 5044-2010) as basic metadata for retrieval and use of the images.
It is important to establish naming conventions and version control for images captured and maintained as part of business processes. A well devised naming structure can ensure consistency and be integral to efficient retrieval.
Image Management Systems (IMS) can be used for very large collections and can generate unique non-descriptive file names (for example, unique numbers) automatically for images, but it is important that the IMS is preserved over time to allow continued access to the images.
If you need to edit or optimise an image, for example, to improve quality or adjust for web use, always start with a working copy. Keep a record of any changes you make, especially if the image is used as evidence in legal cases.
Images should be stored in reliable and resilient IT systems such as in active systems or RAID hard drives to prevent loss or damage. Removable storage devices, such as USB flash drives, should only be used for low value images.
Compression reduces the size of image files, but it can also lower quality.
Compression is generally in 2 categories: lossless or lossy compression.
- Lossless compression uses redundancy reduction techniques which find patterns and repetitions in the image data and express these more efficiently. For example, if there are 25 black pixels in a row, during lossless compression information would be recorded for one pixel, with directions that the next 24 are all the same, rather than recording each pixel separately.
- Lossy compression uses some redundancy reduction techniques combined with irrelevancy reduction techniques which aim to remove or alter information that makes little or no difference to the user’s perception of the image. For example, some of an image's colour information can be simplified without perceptible changes. In extreme cases lossy compression can compromise the quality of the image. Lossy compressions transform and simplify the image information in a way that gives much larger reductions in file size than lossless compressions but the information, once disposed of, is irretrievable.6
- If you need to compress an image, use lossless compression so that the image can be fully restored. Lossy compression may be used for web delivery or thumbnails, where smaller size is more important than perfect quality.
Your organisation should be aware of the laws governing intellectual property rights, such as copyright, privacy and data protection, and consider and manage these proactively.
If images include recognisable living people, you should seek permission before making these images publicly available – for example in annual reports or on websites – especially if the images are of a sensitive nature. Metadata can be used to record information about intellectual property rights.
Not all images need to be kept forever. Some images may only be needed temporarily and can be deleted once they’re no longer required under normal administrative practice. For images that are required for business or legal purposes, follow your organisation’s retention and disposal rules.