A review of optical sensization is made in terms of the electronic and molecular structure of dyes. The optical sensitization consists of the adsorption of the surface of silver halide, the absorption of light by the dyes adsorbed and the energy transfer from the excited dye molecules to the silver halide. The dye has also the desensitizing action, which behaves in the opposite direction to the optical sensitization. The characteristics of these four factors can be understood from the concepts of the unlocalized n-electron and of the planarity of dye molecules. Supersensitization and antisensitization are closely connected with these properties of dyes.

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It is shown by the photographic sensitometry that when a chemically sensitized emulsion is etched with a silver halide solvent and then exposed to light, there was a great decrease in the sensitivity at high intensity exposure, but no appreciable change at low intensity exposure. This implies that the sensitivity specks on the grain surface certainly play an essential role in the sensitization of surface latent image at high intensity exposure: that is, the reduction of the recombination of electrons and positive holes, but do not do so at low intensity exposure. It is supposed that the ripening products which play an important role as the sensitizing products at low intensity exposure are suspended in finely dispersed colloidal form in the silver gelatinate envelope in the immediate neighbourhood of the grain, and thus are topochemically distinguishable one from the sensitivity specks on the grain surface. The present authors have introduced the term ‘accepting speck’ to describe the sensitizing products in the gelatin medium, because they accept the large amounts of halogen produced by low intensity light in the gelatin medium of the chemically sensitized emulsion. At low intensity exposure the sensitivity specks on the grain surface only impede the regression of the surface latent image.

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Fading of latent images produced by gamma-rays emitted from 60 Co was studied using emulsions of commercial X-ray films, of a Process Plate or of a negative film.
At 30°C and relative humidity of 68.6%, the maximum rate of fading was observed in a X-ray emulsion of high sensitivity containing the largest silver halide grains. Fading was also remarkable in a Process emulsion. In these emulsions, latent image produced by light exposure showed noticeable fading at 30°C, 68.6% r. H., and influence of radiation upon the stability of latent image was hardly recognized. From these results, it seems that grain size of silver halide is not a predominant factor influencing fading phenomena and that instability is not a particular nature of the latent image produced by high energy radiation.
In a X-ray emulsion, fading of surface latent image was always exceeded that of internal latent image for both light and gamma-ray exposure. So we consider that the surface sensitivity of silver halide crystals is an important factor for the fading phenomena.

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The color positive images that printed in optimum, was consist of three optimum components.
These three components are cyan, magenta and yellow color positive images, and only when these image densities are equivalent in uniformaly, that admitted these components are in optimum.
Therefore to keep optimum correction level in color that required the accurate exposure value determination in the color printing.
But, in generally, color negatives that snaped were appeared with undesinged image compositions, and accurate exposure determination is difficult in practice, as well known.
Authors tried to determine accurate or very near to accurate exposure value for analyse of color negative images, and shows image charactors as the density-freqnency curves.
According to these treatment authors found that it's possible to plane the “Automatic Color Printer” which devices based on the Photo-electronic timer.

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It is discussed at the first on the method of measuring the electronic current density, for variing the exposure value, and on the geometro-optical and the spectroscopic conditions on the practical photographic density.
I propose a method to read the emulsion sensitivity on a characterisic curve, after considered the minimum useful density in the electron-micrographs and preciseness of visual densitometry. I propose also a method to read the gradation, after discussed linearity of the characteristic curves, frequency distribution of negative contrast and exposure range of the photographic paper.

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