Journal of the Society of Motion Picture Engineers (1930-1949)

June, 1941] MEASUREMENT OF PRINTING DENSITY 635 MR. LINDSAY: If you think that the positive spectral response is desirable in the measurement of negative materials, do you agree that the optical and spectral characteristics of an average sound-projection machine should be simulated for the correct measurement of positive materials and fine-grain prints? If we look at the negative and fine-grain films as the positive or print sees them, then we should look at the prints as the projectors see them, optically and spectrally. Dr. FRAYNE: When we come to measuring print densities, that is something else. On a print we have a sound-track and also a picture. As far as the soundtrack is concerned, it is obviously logical in view of the stand taken here that the sound-track densities should be measured as the photocell sees them in the reproducing equipment, with the same spectral response and the same light scattering, and so on. There has been some work done along that line. We have in our laboratory what we call a projection type densitometer. There is, however, no instrument available to the public at this time. Nothing has been standardized. It would mean more or less standardizing the optics of the reproducing machines. At the present time there is a wide variation in the optics of reproducing machines. I do not believe it would be practicable at this time to put on the market a densitometer that would pressure print densities in the manner proposed. I might also point out that the picture is seen visually, of course, but not diffusely. That calls for another kind of densitometer. Whether the resulting confusion would be worth the effort, I do not know.