[do we need a description of preparing images that are not collections??]

Digitizing

When digitizing collection items, it is important to know what you want to do with the scan. PVMA has three main uses for these files: 1. As a visual record in the PastPerfect curatorial database, 2. For general museum uses such as using in the PVMA website or printing of high-quality copies at 300 dpi and 3. for the American Centuries website which offers users a zoom feature.

Scanning Documents and Books on the Flatbed Scanner

We recommend scanning all documents and images in 24 bit color (including black and white items) RGB color mode with an approximately 80 MB target file size. This will result in a file that can be printed up to 11″ x 14″. This also results in a file that is about 6000 pixels on the smallest side which is large enough to support zooming on the Centuries website.

File size (megabytes) indicates the amount of information in the scan. File size can be thought of as Resolution x Document’s physical size = File size. Resolution (dpi = dots per inch) is only one factor in the quality of a scan. It’s safer to use file size as the benchmark as it’s a more comprehensive measurement than resolution. Smaller items (such as a business card) require a higher resolution than larger items (such as a poster) The larger the digital size (megabytes) of the file, the more detail it contains. 

Using the flatbed scanner, scan documents and book pages at 100% of original size with the resolution set using the guidelines below. If in doubt, scan at 600 dpi. Always use 24 bit color (including black and white items). Save all files as uncompressed TIFFs and store on the PVMA Image Archive in the appropriate folder.

• Small items – less than 6” on the largest side: 1200 dpi
• Medium items – between 6” and 12” on the largest side: 600 dpi
• Large items – over 12” on the largest side: 300 dpi

Photographing Objects/Artifacts

Ideally objects should be photographed with a color card and scale indicator and using lights and a seamless background. The photographs for the original Centuries website included a color card that was used when making the Master Tiffs but then cropped out before saving the Tiff.

For the default view, be sure to include the entire object with some space around it; make sure there’s enough space to crop out the color card without inpinging on the item. If this isn’t possible, take two photos: one with the card and one without. 

The images should be captured at the highest size/quality possible for the camera. The resulting image files should be a minimum of 6000 pixels on the shortest side with a target file size of about 80MB. Image files should be RAW or TIFF format when saved to the camera’s memory card. We should keep an archive of the untouched RAW files in the PVMA Image Archive in a “RAW“ folder.

Image Processing

1. Open the RAW file in Photoshop. Check to ensure that the settings are: Color Settings > RGB.
2. Rotate image if necessary to get it straight. The best way to do this is to use the Ruler tool to draw a line along a straight edge in the image and then from the top menu, select Image > Image Rotation > Arbitrary.
3. Undistort the image if the perspective is skewed. If a rectangular image such as a painting is badly keystoned it might need to be re-photographed.
4. Color correct using the color card and the Curves dialog box. (Image > Adjust > Curves) Use the eyedroppers to set black, white and gray.
5. Crop close to (about 10 pixels) but not within the edge of the page or document. For images of objects leave a generous and even amount of space around the object.
6. Save the file as an uncompressed TIFF file format (“xxxx.tif”) – be sure to not overwrite the RAW file. Processed Tiff files should be saved to a “Masters” directory in the image archive and periodically backed up. Please be sure to follow the Image File Naming Conventions!

Additional Resources

More useful information about photographing and scanning can be found on the Maine Memory Network website although note that they recommend a lower resolution standard.

Digitization Best Practices for Three-Dimensional Objects from CARLI: Consortium of Academic and Research Libraries of Illinois

3-D Objects:

https://www.carli.illinois.edu/sites/files/digital_collections/documentation/guidelines_for_3D.pdf

2-D Documents

https://www.carli.illinois.edu/sites/files/digital_collections/documentation/guidelines_for_images.pdf

For more detailed and comprehensive information see the Library of Congress’s “Technical Guidelines for Digitizing Cultural Heritage Materials: Creation of Raster Image Master Files”:

http://www.digitizationguidelines.gov/guidelines/FADGI_Still_Image-Tech_Guidelines_2010-08-24.pdf