A key takeaway covered in the first session was understanding the concept of pixels—which is generally defined as the basic element of a digital image. The amount/size of pixels within a digital image will determine the resolution and quality of the image. This lead to the discussion of pixels per inch (ppi) vs. dots per inch (dpi), bit depth, how to calculate the spatial resolution of an image (ex. 3000 pixels / 10 inches = 300ppi), and the concept of resolution threshold.
Resolution threshold is the point at which adding more pixels to an image does nothing to enhance the image, but will needlessly increase the file size due to the additional pixels. So it is important to set the proper resolution on scanners and cameras. This is a concept that really stood out to me because—like most digitization labs–having enough drive space with a continually growing digital collection is always a factor.
We were also introduced to the CDP Digital Imaging Best Practices guide for image capture, presentation and storage. This is available on the LYRASIS website, and is a great resource for individuals who are new to the digital imaging field. I like that the creators of this guide wrote it in a way that is relatively easy for newcomers to digest.
The second session lead with a great overview of tonal range (the amount of light and dark within an image). Setting the proper tonal range of a black & white image is important because it ensures all the information from the original image is captured. Leigh Grinstead demonstrated how tonal range can be determined by use of a histogram, which is commonly used in Adobe Photoshop.
In regards to color images, it was interesting to realize that there is not an industry-wide color standard when it comes to the calibration of scanners, monitors, digital cameras and printers. It varies by brand. This means that an image’s color displayed on a Mac monitor can be displayed differently on a PC monitor. Leigh Grinstead noted some solutions to this, such as including a color bar alongside the image of the digitized master file(s) when it is digitized.
I also liked how she provided images of digitization labs that are located at other academic institutions. Seeing the range of digital capture devices used in other digitization labs was insightful.
This was a very useful supplement to the training I have received from Chelcie—providing the opportunity to add to my overall knowledge of digital imaging. What I especially liked about the webinar was the interaction between the viewers and the host. She consistently kept the audience engaged by asking questions and seeking ongoing feedback from the information she provided.
It is also nice to have the ability to listen to the recordings and view the slides for future reference. I plan to refer to much of this content for the digitization of any upcoming photographs, maps, film negatives, artwork and born-digital files.