Using Photoshop, students then create JPEG derivatives at
medium compression with a resolution of 150 ppi with 1000 pixels
on the long dimension (following the CDL Guidelines for Digital
Images: California Digital Library, 2009). The “ar” on the archival
files are changed to “ac” on the accession numbers to reflect the
change in file size and specifications. In this process the archival
masters are reduced in size to approximately 200 KB, appropriate
for web viewing, and yet still large enough to zoom for some
degree of detail.