| 摘要 |
PURPOSE:To attain image recording with high quality based on a binary coded data by applying a spatial frequency process emphasizing high frequency range to an input image signal, and binary coding the said signal by using the value obtained through the said processing as a threshold value. CONSTITUTION:The image is converted to an electrical signal by a photoelectric converting element. The obtained input image signal is subjected to processing including the spatial frequency processing. The resulting value is taken for the threshold and the density level of correspondent image is binary-coded. For instance, when obtaining an input image by sampling from an original image A, smoothing or an image occurrs due to the influence of size of aperture and the resolution of the lens, therefore, the actual input image goes to a form B. When the high frequency emphasis is applied on the said data of form B, it goes to a form C in the figure. These data of A, B, and C intersect approximately at one point. At the said point, the size relation between the B and the C reverses. And this inversion in size relation corresponds with the white/ black level variation of the original image A. Accordingly, by using the C as the threshold value of B, (vice versa), the B can be binary-coded, and A can be reproduced with considerable accuracy.
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