Since Rossmann (1963), the power spectrum has been used frequently to evaluate the granularity of X-ray film. However, clear explanation has not been given for this power spectrum measurement. The following two methods were used to measure this power spectmum and a basic investigation was performed.
The first method involved the commonly used measurement for power spectrum with a microphotometer. The other was the measurement of power spectrum with a newly developed 16k dots×100 lines FFT system using a microscope-television camera system as input device.
The films were single-emulsion Kodak EKTASPEED films with emulsion densities (ED) of 0.08, 0.12, 0.14, 0.20, 0.37, 0.55 and 0.87.
Since microphotometer input gives a power value dependent on the emulsion density, in the 30 LP/mm or less spatial frequency non-correlative region, higher power value resulted as the emulsion density of the film became higher.
By measuring with microscope-television camera input system, the power value in the spatial frequency non-correlative region showed an emulsion density dependence which was characterized by a single peak at emulsion density of 0.20. Conclusions were as follows.
1. A 16k dots×100 lines power spectrum measurement system using a microscope-television camera system was developed.
2. Heretofore, the granularity of film was evaluated from the power spectrum using the power value in the spatial frequency non-correlative region. Since this power spectrum is determined by factors such as the measurement system and the film emulsion density, there were problems with the evaluation thus obtained.
3. A new method for evaluating granularity from the power value in the spatial frequency noncorrelative region through a power spectrum measurment system utilizing a microscope-television camera system as input device was established.

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The object of this study is to make clear the relation between Ag-particle size of film and changes in temperature of developer.
The films that used in it were Ultra-speed film (DF-57) and EKTASPEED film (EP-22), produced by Kodak Co. Ltd. Films were developed at temperature of 10°C, 15°C and 20°C for 4min, at 25°C for 2min, 30°C for 45 sec and 32°C for 30sec. The photographic density of the films used in this study was 0.3. These films were exposed by the time scale method.
The size of Ag-particle was measured as follows: one Ag-particle magnified 200-fold under a microscope was measured of the length along the X-axis by determining X and Y coordinates on the image. Thus, we measured two dimensional particle size in one dimension. However, as the twodimensional Fourier spectrum shows isotropic distribution, we considered that one dimensional measurements might well evaluate Ag-particle size. A total of 10⁴ Ag-particles could be measured in each image.
The following results were obtained.
1. With change in themperature of the developer from 10°C to 32°C, the film speed elevated twice for EKTASPEED film and four times for Ultra-speed film.
2. For both EKTASPEED film and Ultra-speed film, the distribution pattern of Ag-particle size resembled Poisson distribution. The peak of the distribution, namely the particle size accounting for the highest number of particles, appeared at 3 to 4μm for EKTASPEED film and 2 to 3μm for Ultra-speed film.
3. The size of Ag-particles in these peaks remained unchanged under change in the temperature of the developer. With raising the temperature of the developer, the peak value lowered.
4. Taking the distribution of particle size at a developer temperature of 20°C as the standard, particle size distribution at each temperature was determined. For both films, at temperatures lower than 20°C, particles were smaller size as compared to those which appeared at the temperture of 20°C, while particles of larger size prevailed at temperatures higher than 20°C.
5. Looking into changes of particle size in relation to temperature for both films, less changes were observed in particle size with changes in temperatures in the range of temperature 15°C to 25°C for EKTASPEED film. On the other hand, for Ultra-speed film remarkable difference in distribution particle size was seen between 15°C and 25°C in temperature.
6. These findings indicate that EKTASPEED film is more resistant to changes in temperature of the developer in comparison with Ultra-speed film. The latter maybe said to be sensitive to changes in temperture of the developer. From these results, it was found that cautions should be exercised for determing the temperature of development in order to utilize characteristic properties of Ultraspeed film.
7. With raising in the temperature of the developer, the size of Ag-particles enlarges. This can be explained as follows: in developing the film, Ag-particles were mobilized by protrusion of metallic silver particles. Thus, Ag-particles aggregated together in the vicinity might appear as large particle. We could demonstrate this experimentally.

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