Still Image Digitization
Initiating and managing a Digitization project to meet the FADGI guidelines.
You can find the guideline PDF at: Digitization Guidelines
1. FADGI for your institution
2. FADGI and the vendor
3. Different levels of FADGI compliance
4. Develop your specifications using FADGI
FADGI for your institution
If youre following FADGI, it should mean that your institution has a focus on the creation of a master file or as the FADGI documents call it “creation of raster image master files”. It is also important that your institution is committed to the maintenance and longevity of these master files. If not, you may be spending extra money to create high quality masters just to get compressed derivative access files. FADGI Images have well defined technical parameters that are meant to produce images of uniform quality. As you will read, there are different levels of quality that can be achieved that still fall within FADGI compliance. Master files will be a reasonable and faithful reproduction of the original items (the amount of enhancement to the master file varies and can be specified or limited as part of your requirements).
FADGI and the Vendor
There are specific areas of FADGI that address the Digitization Environment. You want to be sure your vendor can meet all of these requirements. The guidelines are specific on viewing conditions, the room, and the monitors. Seek vendors that can address how they meet these standards. If a vendor doesnt meet the environment specifications they may be relying on making post process adjustments to the images which can degrade your master files and fall below the FADGI standard (or a specific quality level of the standard). When getting quotes it is important to see that the various vendors are quoting for the same level of service.
Objective Performance Measures and Guidelines
There are Device-level targets and object-level targets used to measure scanning performance. Technical Targets are designed to measure performance of the scanner/camera device and to capture or measure characteristics as a result of the settings used in that session. The device target is typically a large technical target that will be captured at the beginning and end of a session to determine that the device has met the performance measures and image specification (like ppi, bit depth, color calibration). Sessions can be defined as the item (like a book or a box) or can be per shift or per day.
The object target comes in multiple sizes so you can include it in each capture alongside the item being digitized. This is more popular for photographic and image based collections where measuring the color in each capture is critical (for example items for reproduction or preservation).
You can see example images with object targets in the FADGI PDF on pages 54-58. Digitization Guidelines
Some equipment can be calibrated to meet the performance matrix and some lower end equipment cannot or may fall below a required quality level. Project cost is generally affected by the cost of the equipment being used and the cost of the equipment seems to have a direct correlation on the level of quality that can be achieved.
The evaluation process recommended by FADGI provides measures for both camera/scanner as well as individual images in an objective manner that utilizes software. Subjective visual inspection should also be a part of the quality assurance process.
GoldenThread by Image Science Associates is the target that was used by the FADGI Still Image Working Group to generate their performance data. It is not the only multi-featured target available. Targets are also available from Universal Test Target and Imatest. There are also single featured targets available. Regardless of what target is used the results should be tested, documented and presented as part of the projects deliverables.
Different levels of FADGI compliance
What level is right for you?
FADGI offers performance ratings from a single star up to four stars. These levels can be hard to measure or prove when you get your images back from a vendor. One way to check results is to evaluate the required targets by manually checking the results in Photoshop or by running the target through the evaluation software. For the Golden Thread target you can get the software from Image Science Associates website at: Image Science Associates Software
You can also require that your vendor send you the results in a spreadsheet or screenshots of the graphic interface that displays pass/fail results. In a production environment two to three star should be the expected range. Four stars is better suited in a lower volume studio where each image can be carefully measured against each of the matrix values. Four star levels have very tight tolerances that require continued monitoring (which in a production environment results in higher prices). Most equipment or components will have a certain amount of drift. For example, lighting can fluctuate or a flash not fully charge or a shutter that doesnt release exactly the same every time. In production environment it is important to have a balance of good equipment, good procedures, and a well-trained team.
When deciding on what quality level you want a vendor to meet, you may want to follow what the Federal RFPs use; they require vendors to meet three star quality. You can also consider requesting one or two matrices at three or four star while the rest can fall lower. It will really depend on the goals for your individual project. Just be sure to clearly define what your project requirements are and remember that more is not always best if it inflates the price of your project unnecessarily.
In addition to the different levels of quality ratings there are also two levels of digitization specifications broken out by different types of material.
♦ Textual Documents, Graphic Illustrations/Artwork, Maps, Plans and Oversized
♦ Photographs - Film ⁄ Camera Originals - Black and White and Color - Transmission Scanning
♦ Photographs - Prints - Black and White and Color - Reflection Scanning
♦ Aerial - Transmission Scanning
♦ Aerial - Reflection Scanning
♦ Objects and Artifacts
Develop your specifications using FADGI
Once you know what material you will be scanning, you will want to find the chart that matches the material you want to have digitized. For example, you have 35 mm color slides. You will use the chart for Photographs, transmission scanning. Next determine if you will follow what is considered the higher standards, the “Recommended Image Parameters” or “Alternative Minimum.” Both are FADGI compliant but depending on your institutions goals, you may be able to follow the lower standard. It is important to understand what your end goals are because the two levels will affect the prices when outsourcing. If you dont have to go with the higher standard, you may lower your cost by selecting the alternative minimum specifications.
Continuing with our example, if we are writing specifications for the recommended standard the specs are as follows: 24 bit, color 2800 ppi (this is based on the live image area of a 35mm slide being approx. 1.42”)
If we were writing specs for the alternative: 24 bit color, 2100 ppi
For a discussion on FADGI metadata please see our webpage on Metadata.
In summary FADGI is a guideline worth following and incorporating into your institutional guidelines, but as you read in some of this discussion it has an impact on price/cost and a dedication to master files in addition to access files. Since the guidelines have different levels of compliance, it may be something your institution could start to follow in phases while building up to higher level of compliance for more critical collections. It doesnt have to be all or nothing with these guidelines, but it is important to know what you want and be clear when working with vendors so that they understand and can help with the compliance levels to meet your goals.
If you have comments or would like to see papers on more details about FADGI please feel free to contact me at email@example.com or drop us a note.