Artstor adds content to the Digital Library through two means: managed production (the digitization of new content with production overseen by Artstor) and contributions (the addition of existing digital files generously offered by contributors).
Image source materials
The source materials for digital capture vary for each Artstor collection. Original source formats include 4x5 and 8x10 transparencies or negatives; black-and-white prints based on original photography made from the object; 35mm color slides, many made from reproductions in the scholarly literature; and direct, high-resolution digital photography of objects.
We are often asked about Artstor's digitizing specifications. However, it is difficult to provide "blanket" specifications that would fit all possible scenarios. Our digitizing specifications vary according to the format and quality of the source material as well as the image's content. For example, 8x10 nitrate negatives can be scanned at a much higher resolution than 35mm slides. A 4x5 transparency of graphic art with large color fields would be scanned at a lower resolution than a 4x5 transparency of mosaic details. A 35mm slide with a "sharp" image would be scanned at a higher resolution than one with a "soft" image, since scanning a soft image at too high a resolution would render the resulting digital file blurry when zoomed in upon using tools in the Artstor Digital Library.
The image quality-control process
Artstor strives to offer relatively consistent image quality across collections independent of the original source media. It does so by means of an ongoing, rigorous quality-control process. Every image is viewed, tracked in a management system, and re-scanned if errors are found. Artstor staff also rigorously check contributed digital content: if the existing images can be improved or enhanced, then with approval from the contributor Artstor will often create new digital files by restoring or enhancing the contributed images.
On occasion, the original source color film scanned by Artstor may have faded or acquired a color cast. Where feasible and appropriate, Artstor attempts to restore original color to the digital scans, preferably under the guidance of the original photographer or the archive that owns the collection, and paying close attention to the distinctive physical characteristics of the photographic source. When expert guidance is unavailable, Artstor does not seek to attempt such restoration, deeming it inappropriate and the results unreliable. As a result, users will sometimes find a range of image quality, as is typically the case with other analog and digital image archives.
Continuing to improve image quality
While there can be a range of image quality in Artstor, we have been proactively improving our content by working closely with museums, archives, libraries, scholar photographers, and authorized image agencies such as Scala and Erich Lessing. Image quality will only continue to improve over time as the Digital Library increases its content.
Wassily Kandinsky (1866 - 1944); Circle in a Circle, 1923; Philadelphia Museum of Art; Artstor ID# PMA_1039758596
© 2007 Artists Rights Society (ARS), New York | ADAGP, Paris