About lillie (the chinagirl)

Printer Control
Printer Control is necessary to iron-out day-to-day variations so that the desired colour and density can be obtained in a print or intermediate. Variations may occur in printer lamp output, transmission of lenses or filters, stock sensitivity, or in the chemical process.

Photometric control
It is important that printer, stock, and process remain individually within close tolerances so that errors in one part of the system are not masked by changes in another part. The light output of a printer can be measured independently by a photometer, collecting light at the gate. One useful form of printer control consists simply of taking regular readings, adjusting the set-up to maintain a constant reading. This technique is particularly usefull during printer maintenance, lamp changes, etc. Many photometers may be fitted with scanning probes so that the evenness of illumination across the gate can be measured.

Sensemetric control
Routine tests, however, normally take the form of printing from a standard negative, which consists of an area of 18 per cent neutral grey, or a LAD patch and often includes a close-up face for visual reference. Tests are printed regularly on the batch of stock to be used, processed and assessed visually and densitometrically by comparison with a standard reference print.
To correct the density or colour, a change must be made to the exposure set-up.

taken from: Motion Picture Filmprocessing, 1985, Dominic Case, focall press