Quality control of a laser camera with the SMPTE test pattern: optical density variations with printing format and frame position.

The purpose of this study was to investigate the use of the Society of Motion Picture and Television Engineers (SMPTE) test pattern in the quality control of a modern laser camera and the variations in the optical density (OD) of the film when different formats are used. The SMPTE pattern was printed on all the available frames in eight different formats. Furthermore, six films were produced using the same format to check for any reproducibility problems. The OD values of the 11 step greyscale of the SMPTE patterns were measured with a densitometer, as well as the OD of steps 10 and 11 of the 16 step monitor greyscale printed to the left of each frame along with the SMPTE pattern. Variations up to 0.2 were observed in the OD of the same step when different formats and different frames within the same film were compared. Furthermore, the OD variations with frame position were found to follow a specific pattern. The OD variations observed with printing format and frame position can not be explained with certainty. They may indicate a laser camera malfunction and, if this is the case, limits to the maximum variation allowed should be set.