In 1987 someone rummaging in a second hand bookstore in Vienna came across a set of about 400 color slides. Upon examination, they turned out to be images of the Lodz ghetto, taken by Walter Genewein, the Nazis' chief accountant. After Genewein died, his companion sold the pictures to the bookstore in Vienna. From there, they made their way into the collection of the Jewish Museum in Frankfurt, and also into Jablonski's movie "Photographer".
Genewein must have had his reasons for selecting one view over another and for carefully numbering the images, as if to create a sequence.