Interpreting DAC Digital Images, Phase 1
Some artifacts of the capture process are visible in images from the first direct-capture phase of the DAC Digital Imaging Initiative. (If a link from an image page led you here, this information pertains to the image on that page.)
Most noticeable is barrel distortion visible in images of smaller objects such as the Goya prints provided for Spanish 223. Also noticeable in the Goya Caprichos is some variance in color rendition due to the imaging of selected prints early in our prototype phase, and the later imaging of the intervening prints in the series (although some variation in tone exists in the works themselves).
Other examples are the moiré effect seen in some images of engravings with highly regular line systems (e.g., the prints after Goltzius presented for Latin 202), and the glare seen along the sides of some highly glossy photographic prints. As the project progressed since these images were made, we've been developing procedures for resolving some of these issues in its current, second phase of direct capture.
In editing these images, we tried to balance faithful representation of original objects (philosophically our first priority) and legibility on screen (pragmatically crucial for obvious reasons). In some cases this led us to present digital images with somewhat more contrast than the originals they represent (e.g., in images of the American Art-Union portfolio for American Studies 114 / Art History 272).
When studying these images, it's important to keep in mind that tonal rendering varies tremendously from monitor to monitor. These images were processed using a Sony CPD-200sf 17" monitor set to Macintosh gamma, and checked on a 15" Apple MultiSync monitor set to PC gamma (with darker midtones); but (1) our calibration was only approximate (lacking true colorimetric equipment), and (2) most monitors used for web browsing are wildly out of calibration.
Because of this, any interpretation of color values or tonal density in these images should be undertaken with extreme caution. More reliable are visual analyses based on observations of such things as the marks with which a printmaker created an image, broader aspects of visual design, and iconographic content. One last warning: you may wish to attend to the dimensions of the original works, in order to try to see imaginatively past the leveling effect of viewing all images at a standard size on your computer screen.