When exposed to light through the reseau, the film's emulsion was exposed to a single color of light.
From the en.wikipedia.org
Benson Photoshopped out thousands of the reseau marks, then filled them in with pixels cloned from nearby on each image.
From the washingtonpost.com
Reseau de Transport d'Electricite, or RTE, expects France to have 5,000 megawatts of wind turbines installed by the end of 2010, less than half a target set in 2006 for capacity of 13,500 megawatts.
From the bloomberg.com
More examples
A net or mesh foundation for lace
A network of fine lines used by astronomers as a reference for measurements on star photographs
The Hasselblad Lunar Surface Data Camera was fitted with a Reseau plate, which provides a means of correcting images for the effects of film distortion. The Reseau plate was made of glass and was fitted to the back of the camera body, extremely close to the film plane. The plate was 5.4 x 5. ...
A grid that is photographed by a separate exposure on the same plate with star (or galaxy) images. [H76]
[JP 1-02] (DoD, NATO) A grid system of a standard size in the image plane of a photographic system used for mensuration purposes.