Although the Municipal Archives had already gained quite some experience in large scale digitization, both on-site as well as externally, this project had a big surprise in store. While the digitization work for the Eilers retrospective was still going on, it appeared that the original colour processing could be imitated by digital means.
First, the sets of 3 black-and-white negatives were scanned, and then each individual picture was converted into a positive one. Subsequently, the pictures were turned into the colours cyan, magenta and yellow, in line with the original gelatine layers. The type of filter used for making the shots was often indicated on the negatives and this facilitated the digital colour processing. The three scans were put together by laying transparent (monotone) sheets on top of one another and then it was a matter of shifting them back and forth until they fitted to perfection. Only then could the individual pictures be assembled definitely.
This image shows how three separate colour negatives form a single picture The final result was a beautiful colour picture. However, the colours of the new pictures are not always quite the same as the colours Eilers himself chose, as one can see from the limited number of original colour prints that have been preserved. But such deviations can also be corrected by digital means, resulting in the tomatoes having the red colour Eilers had in mind after his experiments.
For more detailed information on this technique, see the animation on the Municipal Archives website