Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Fumio Owada

Yukio Tsuda

Yoshiko Yamaguchi

A system preprocesses analog picture image signals formed by scanning a manuscript prior to binarization into signals representing black or white according to a predetermined threshold value, compares a digital signal of a picture element to be corrected and of a signal of a picture element at least one main scanning line before the picture element to be corrected and positioned at the same position as the picture element to be corrected in an auxiliary scanning direction which is attenuated with each main scanning line or lines are compared. The one of these two signals having a larger level at a given time is used as a reference signal showing the nature of tone of the manuscript. When the level of digital picture image signal of the picture element to be corrected is closer to a black or white than the level of the reference signal, the level of the digital picture image signal is adjusted towards black or white. In other cases, the level of the digital picture image signals is maintained. By this operation, the nature of tone of the manuscript is emphasized and the accuracy of judgement in later binarizing the analog picture image signals is improved.

Binarizing system of picture image signals

In a binarizing system wherein analog picture image signals produced by scanning a manuscript picture image is quantized and the quantized signals are converted into digital picture image signals which are binarized into signals representing black or white according to a predetermined threshold value, some picture image signals of picture elements on the same main scanning line as a picture element to be corrected and positioned before the picture element to be corrected among the digital picture image signals are selectively extracted, and at least one of the picture image signals whose level becomes a maximum or a minimum is further selected from the extracted picture image signals. The picture image signal thus selected is used as a reference signal showing the nature of tone of the manuscript picture image for subjecting the picture image signal of the picture image to be corrected to a calculation emphasizing the nature of tone of the picture image to be corrected in the manuscript picture image.

The invention is a driving circuit for an electrostatic recording head which reduces the turn-on time, the storage time and the turn-off time of the driving circuit output pulses. Mutually complementary first and second transistors are connected with their collectors in common. A first driving signal is supplied via a coupling capacitor to the base of the first transistor, and is also supplied to the base of the second transistor. High voltage is supplied to the emitter of the first transistor. The output signal is obtained from the interconnection of the common collectors. The first driving signal has three sequential levels, two of which occur within the time period when the recording picture signals are supplied. The first level e.sub.2 is the highest and occurs during the beginning portion of the recording signal and the second level e.sub.1 is lower than e.sub.2 and occurs during the remaining portion of the recording signal. The third level is the smallest (i.e., zero or ground level (o)) and occurs immediately after e.sub.1 when no recording signals are supplied. A second driving signal is applied to the emitter of the second transistor. The second driving signal has two non-zero sequential levels (i.e., e.sub.4 and e.sub.3). The first level e.sub.4 is the larger of the two and occurs at the end of e.sub.1 and continues for a time approximately equal to or greater than T.sub.c. The second level e.sub.3 occurs immediately after e.sub.4.

Growing community of inventors

Hachioji, Japan

Fumio Owada