We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
1P42, but the photosensitive surface is too far from the film to make the tube a good receiver. Means to gather all the light, coming through the sample tested have to be provided. This is important when measuring the density of negatives, as all silver images and cyan dyes show a greater density when measured in a spectral system.
We know of only three methods to measure true diffuse density:
1. placing the sample to be measured directly in contact with the photosensitive circuit,
2. utilizing a sphere, up to now considered the standard in the motion picture industry, and
3. utilizing an integrating bar.
The first method, theoretically the most simple, is nearly impossible in actual practice. The second method, excellent in black-and-white measurements, introduces too much loss into the system. Depending upon the method of coating and the size of the sphere, a loss of light equivalent to inserting a density between 1.3 and 1.5 is the minimum obtainable in practice. Adding this loss to the insertion loss of the optical filters will restrict any instrument using a design similar to ours to a maximum density range of 3.0.
The third method, the integrating bar with a diffusing surface toward the film to be measured, retains all the advantages of a sphere. It introduces a loss of light equivalent to inserting a density of 0.6, making diffuse color density measurements of 4.0 possible.
Table I shows the measurements obtained from three common sound track emulsions when measured with a sphere, integrating bar and spectral type of instrument. For comparison they were measured with a sphere-type densitometer having a visual-type color characteristic and the visual filter on our Model 1503A with and without the integrating bar.
The differences between readings of the sphere type and 1503A with the integrating bar are due to difference in spectral sensitivity of the two instruments.
Figure 2 shows the spectral distribution of the light source and the visual filter with this light source compared to an average eye characteristic.
Figure 3 shows the spectral distribution of the three combination color filters with the light source shown in Fig. 2.
As mentioned before, the Corning No. 9780 infrared absorbing filter is
Table I. Comparison Test of Three Common Sound-Track Emulsions (using Pathe 2B Sensitometer).
E.K. 5373, 4-min dev. DuPont 836, 5-min dev. DuPont 831, 9-min dcv.
Step
RA RA RA
1100B 1503A 1503A-S 1100B 1503A 1503A-S 1100B 1503A 1503A-S
1
0.04
0.03
0.05
0.05
0.05
0.07
0.09
0.09
0.13
3
0.06
0.05
0.08
0.06
0.06
0.09
0.11
0.12
0.15
5
0.11
0.09
0.16
0.12
0.10
0.19
0.18
0.19
0.26
7
0.19
0.17
0.29
0.20
0.17
0.31
0.40
0.44
0.56
9
0.33
0.28
0.48
0.33
0.29
0.50
1.00
1.08
1.37
11
0.49
0.46
0.71
0.53
0.48
0.75
2.05
2.16
2.63
13
0.69
0.66
0.95
0.77
0.71
1.06
3.18
3.28
3.75
15
0.90
0.88
1.21
1.07
1.00
1.43
3.87
3.97
4.+
17
1.12
1.10
•l.47
1.39
1.33
1.80
19
1.31
1.31
1.67
1.71
1.67
2.13
21
1.45
1 .47
1.81
1.94
1.95
2.38
Gamma
0.69
0.69
0.88
0.96
0.96
1.17
3.66
3.66
4.68
Q
1.27
1.22
1.28
186
September 1952 Journal of the SMPTE Vol. 59