View source for Recommendations for the Acquisition, Processing, and Archiving of Digital Media

iDigBio is pleased to offer the following recommendations for capturing, processing, archiving, and distributing digital images based on work of the Developing Robust Object-to-Image-to-Data Workflows Working Group (DROID), a review of industry standards, input from the broader collections community, and feedback from iDigBio staff. 

These recommendations are divided into four clusters: image acquisition, image archiving, image derivatives, and image distribution.

==Image Acquisition Recommendations==

*Camera RAW is the preferred format for recording camera images.
*Scanner images should be recorded in 24 bit or higher at 300-600 ppi in TIFF format.
*Record at the highest native resolution available for the imaging device.
*Adjust white balance settings to match the light source.
*A visible color checker and scale are recommended, as appropriate.
*Adobe RGB or sRGB are the preferred color spaces and should be stated in the metadata.
**CMYK color space should be avoided.
*Image file names should be restricted to alpha numeric characters, without spaces or other special characters, underscore (_) and hyphen (–) excepted.

==Image Archiving Recommendations==

*Archiving images is strongly recommended and is viewed as an institutional responsibility, governed by institutional policy.
**Archived image files should be permanently retained in a secure, redundant environment on institutional infrastructure or commercial back-up services.
*Uncompressed DNG is the preferred archival format.
**Images captured in proprietary camera RAW format (e.g., CR2, NEF, PEF, etc.) should be converted to Digital Negative format (DNG).
**Conversion to DNG can be accomplished via Adobe DNG Converter, available free from Adobe.com, or via Adobe Photoshop or Adobe Photoshop Lightroom.
*Uncompressed or lossless compressed, unmodified TIFF at 24 bits or higher is an alternative archival format.

==Image Derivative Recommendations==

*JPEG and JPEG 2000 images should be saved at their native dimensions (spatial resolution).
**Manually increasing resolution (e.g., alterations to image size or ppi or dpi settings) beyond that recorded by the camera may insert derived data or unwanted visual artifacts into an image file and is not recommended.
*EXIF, IPTC, and other image metadata (including JPEG 2000 XML data), including that added at time of processing, should be preserved in perpetuity and distributed with all derivative and distributed copies of images.
*Image processing should be carried out only on DNG or other RAW files to prevent accumulated data losses and potential image degradation by repeated processing of JPEG and TIFF image files.
*Excessive image manipulation or compositing, including sharpening, enhancing color saturation or balance, and adjusting contrast should be avoided. 

==Image Distribution Recommendations==

*Images uploaded to aggregators and portals should be ‘fit for display’.
**Lower quality images should be distributed to aggregators and portals only when there is no higher quality image available.
**When a low quality image is uploaded or distributed, the metadata for that image should indicate that it is the only image available for that specimen. (is this really necessary??)
*JPEG format at native resolution and minimal compression is preferred for distribution via the internet.
**Lossless compression is preferred.
**When lossless compression is not an option, lossy compression at the lowest level is preferred.

==Fit for Display==

<blockquote>
“Fit for Display” - This is a technical term that relates to file types and other inline text, encoding or attachments, that are not HTML and that are supported natively, or with helper applications, by web browsers. For instance, most browsers have native support for JPG and GIF images. This allows a browser to render the content of these files types for a user to view.  All other types of web page content, like MP3, require a helper, either built-in or installed. In the preferences for a browser there are list of media types (or MIME types) paired with applications for ‘helping’ the browser display the content of that file reference. A helper application, sometimes called a plug-in, is software that knows how to render/display the content. Recall that HTML is the native language for web browsers.  Other media types, like TIFF and DNG, that require an application other than the browser or plug-in to view their content, fall outside the definition of “Fit for Display”.
</blockquote>

==Industry References==

Universal Photographic Digital Imaging Guidelines
http://www.updig.org/ 

The AIC Guide to Digital Photography and Conservation Documentation American Institute for Conservation of Historic and Artistic Works
http://www.conservators-converse.org/2011/08/2nd-edition-of-the-aic-guide-to-digital-photography-and-conservation-documentation-now-available/ 

Adobe Digital Negative (DNG) Specification
https://www.adobe.com/content/dam/Adobe/en/products/photoshop/pdfs/dng_spec_1.4.0.0.pdf 

DNG information from the American Society of Media Photogrophers' "Digital Photography Best Practices and Workflow".
http://www.dpbestflow.org/DNG

OpenRAW Project - Digital Image Preservation Through Open Documentation
https://www.openraw.org