Digitization Decision Guide
While there are different reasons to photograph/image your collection, this guide will focus on how to image for documentation and research purposes and what to consider when you are determining what sort of image files to create and save (i.e. file type, resolution, etc). Below are select reasons for imaging your collection and a brief discussion of each to aid in deciding what your next steps might be. There are uses for photographs/images of your collection other than documentation and research that may require different formats, resolution, storage, etc.--such as photos for publication or press. This document focuses solely on documentation and research images.
It is important to keep in mind that this document is not a guide for “how to photograph your collections.” This document serves as a guide to aid users in creating digital standards that work well for them or their institutions. There are many “how to” resources online and CatalogIt will be developing a guide including some “quick tips” in the future.
Purpose:
Documentation/ Research
A documentation/research image is an image created for the purpose of documenting the physical appearance of an item for identification and research purposes. It should be of a high enough quality to provide a faithful representation of the item being documented and ideally sized so that important details are visible and the image can be printed on a standard letter size sheet of paper (i.e. in a report) while retaining its quality. Typically, these images are also suitable for web publication, such as in the CatalogIt HUB or to Social Media. Typical images used for documentation/research purposes are usually smaller than 10 MB.
Publication
An image created specifically for the purposes of publication, often in print. An accepted standard for publication images is that they have a minimum resolution of 300 pixels per inch (“ppi”) at the size they are to be published. Typically, publication images are saved in an lossless, uncompressed format such as TIFF because image compression can reduce the print quality of the image. As a result, publication-quality image files are often quite large. Due to the intricacies of proper lighting and setup, especially with 3-dimensional objects, professional photography is typically necessary for publication purposes. Images used for Publication purposes can easily be 100MB or larger.
Preservation
An image that is of a high enough quality to serve as a digital surrogate of the item. This type of imaging will help minimize future handling of the item and thereby aids in long term preservation of the object. Typically, preservation images are also saved in a lossless, uncompressed format such as TIFF because image compression can reduce the print quality of the image and can cause degradation over time. As a result, preservation quality image files are on the larger side. Beyond size, preservation images also require the adherence to strict metrics regarding color balance, exposure, etc. Preservation quality images taken with a professional grade DSLR camera can exceed 50MB in size.
Links with more information on image standards for preservation use can be found in the “resources” section at the end of this document.
Scan or photograph?
For most types of collections, photographing with a camera or mobile device is the quickest and most efficient method of image capture. With a minimal amount of setup, you can obtain good quality images of your items. You can typically zoom in on the image to see fine details and read text on a document or object. For items that you are able to scan (using a flatbed scanner), you will be able to capture higher resolution images and potentially capture the text with the ability to search if your scanner includes OCR technology (Optical Character Recognition). It is important to consider the condition of the item you are scanning - a flatbed scanner emits a great amount of light and as light damage is accumulative, you will need to weigh whether this exposure is necessary for your use. As scanners work best when the item is flat with the lid closed, also consider the fragility of the item - an open book, for example, may get damaged from closing the lid on the scanner, and therefore it is recommended that books are photographed rather than scanned. There is software available that will convert a photograph into an OCR readable PDF (both for your mobile and desktop devices). This may be a better alternative for more fragile items than the use of a scanner.
Other considerations regarding scanning:
Depending on the settings you use for your scanner, scanned files can be very large and take up a substantial amount of storage space. It is important to consider if the item you are scanning really needs to be scanned and at what resolution.
In addition, scanning an item can take a lot more time than a quick photograph. Consider how many items you have in your collection and how much time it will take to scan everything. Do you have the staff time and resources to do this? Consider your end use - is this image for documentation purposes or for publication purposes? A photograph taken with a digital camera or your mobile device will save you and your staff/volunteer time and storage space in the long run, while providing a very good, legible, quality image.
Camera vs. Mobile Device:
Deciding what camera to use depends on your final use. In many cases, the camera on your mobile device will suffice for documentation/research images. Photographing 3-d objects, archives, photographs, ephemera, etc. with your cell phone or tablet will produce a good quality reproduction suitable for identification purposes while providing good reproductions for your average researcher. Newer mobile devices utilize superior imaging technology that allow you to zoom in so you can see the very fine details and even read the text in manuscripts, books, and on objects. Using your mobile device to capture images and upload directly into your CatalogIt entries saves both time and resources - no need to store images on an external server or drive and the one-step process saves time in image processing and uploading to CatalogIt later. You can take comfort in knowing that CatalogIt stores your original unaltered image file, that you can retrieve at any time, and even keeps a backup of all media you upload in a separate geographic region for added security and redundancy.
While most mobile devices do not yet incorporate OCR technology, there are many available apps that allow you to scan using your mobile device with integrated OCR technology, Adobe Scan, for example.
If you are digital imaging for preservation purposes (which is, in essence, creating images as a digital surrogate of the item), or imaging an item that you will likely use in a publication in the future, photography with a professional digital camera or scanning at high resolution with a flatbed scanner is recommended.
It is important to note that there are many factors, aside from size, that ensure you have a proper preservation image. Use of a good camera, proper lighting, color balance, etc, are all contributing factors when creating a good preservation image and should be considered when making the determination of file type and size. There is no need to save a very large TIFF image, and use a large amount of storage, if the image itself does not meet the minimum standards of quality or conform to other standards. The digital photography workflows developed for museums require not just that digital images be captured at a minimum size/resolution but also that they meet a number of metrics regarding color accuracy, white balance, and other technical aspects. For more information on these standards please visit the Federal Agencies Digital Guidelines Initiative.
Guidelines for Imaging Objects:
Below is a list of several different object types and tips on how to more effectively image them for documentation or research purposes.
Book
Process: Photograph
What to image: Front and back cover, frontice page, table of contents.
Dimensions: 3000 pixels on long side
Notes: Most modern smartphones will exceed this specification.
Photograph (print)
Process: Photograph or scan
What to image: Face of photo. Verso if signed. Detail of signature
Dimensions: 3000 pixels on long side
Notes: Glossy photographs can be tricky to light properly making scanning a good option.
Photograph (negative)
Process: Scan
What to image: Transmissive scan of image, where possible entire negative or strip.
Dimensions: 4000 pixels on long side
Notes: Scanning negatives and transparencies can be tricky; among other things, you’ll want to make sure you don’t reverse the image.
Painting
Process: Photograph
What to image: Entire face, with frame. Close up of painting only. Verso. Details of signature and inscriptions.
Dimensions: 3000 pixels on long side
Notes: Diffuse light is ideal for lighting paintings to avoid unwanted shadows and hot spots.
Document
Process: Photograph or Scan
What to image: Front of document, verso if relevant.
Dimensions: 3000 pixels on long side
Notes: For fragile or light sensitive objects, it may be best to take a photograph.
3-D Object
Process: Photograph
What to image: Capture from several angles including “front” “back”, and “sides” if applicable.
Dimensions: 3000 pixels on long side
Notes: Proper lighting is key to minimize shadows or reflections. Consider using a light box or tent for smaller 3-D objects.
Work on Paper (small)
Process: Photograph or Scan
What to image: Capture the full obverse of the work. Zoom to capture signatures and inscriptions. Capture the verso for condition and other inscriptions and notes.
Dimensions: 3000 pixels on long side
Notes: Similar to photographing photographic prints.
Coins or Jewelry
Process: Photograph
What to image: Capture obverse and reverse of coins. Capture jewelry from multiple angles, zooming on any marks or inscriptions.
Dimensions: 3000 pixels on long side
Notes: A light box or tent can be very useful when photographing reflective items like coins and jewelry.
Works on Paper (large or framed)
Process: Photograph
What to image: Capture obverse and reverse. Zoom in on signatures and inscriptions. Photograph flat with copy stand or on the wall or easel.
Dimensions: 3000 pixels on long side
Notes: Lighting framed works from both sides can reduce glare on glazing and shadows caused by deep frames.
Textile (flat)
Process: Photograph
What to image: Capture full textile, obverse and reverse. Zoom in on stitch details and edge. Shoot flat w/ a copy stand or slant board. For very large textiles that are rolled or folded - if you do not have the room to unroll completely, unroll/unfold as much as you are able to photograph for documentation.
Dimensions: 3000 pixels on long side
Notes: Using a slant board and mounting your camera on a tripod is helpful for larger flat textiles. Use a copy stand for smaller flat textiles.
Clothing or 3-d Textiles
Process: Photograph
What to image: Capture from several angles including “front” and “back” if applicable.
Dimensions: 3000 pixels on long side
Notes: Proper lighting is key to minimize shadows or reflections. Use a manikin or dress form for clothing. Consider using a light box or tent for smaller 3-D textiles.
Resources:
Federal Agencies Digital Guidelines Initiative
FADGI is a collaborative effort started in 2007 by federal agencies to articulate common sustainable practices and guidelines for digitized and born digital historical, archival and cultural content. Two working groups study issues specific to two major areas, Still Image and Audio-Visual.
National Digital Stewardship Alliance
The NDSA is a consortium of 260 partnering organizations, including universities, professional associations, businesses, government agencies, and nonprofit organizations, all committed to the long-term preservation of digital information. Members work together to preserve access to our digital heritage. NDSA is hosted by the Digital Library Federation.
Cornell University Library
Tools & Techniques for Archival Research: Cameras in the Archives
Australian Museums and Galleries Association
Online Museum Training - Photographing Collection Items