JPS5910075A - Binary coding device of analog signal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an analog signal lambda value conversion device that binarizes an analog signal such as an image signal. It is designed so that it can be transformed into

Conventionally, in order to convert an analog signal such as an image signal obtained by an image pickup tube or a solid-state image pickup plate using a so-called CCD into a λ value,
Many λ value conversion devices are known, including those that use a fixed threshold value. Among such conventional λ value converting devices, so-called time difference λ converters sequentially sample an analog signal such as an image signal, and sequentially convert the analog signal into a λ value according to the result of detecting the difference between adjacent sample values. For example, the value conversion device is JP-A-Sho,! iA
In this time difference λ value conversion device, as shown in FIG. 1 (4), the image on the film A irradiated by the lamp LP is converted into The signal is converted into an analog signal by a CCD, that is, a photoelectric conversion element using a charge-coupled device, through the LN.
The image with the film FM is not a positive image consisting of a white part W and a black part B as shown in FIG. 1(C), but is a silver halide film. If the image is a negative image consisting of a white part W' and a black part B' as shown in FIG. As shown in Section 1), the following problem occurred when recording in the form of an inverted positive image.

That is, the image signal obtained from the solid-state image sensor CCD, for example, in the Toshiba Corporation TCD10.2C-/ model,
As shown in FIG. 1 (4) to C), a dummy output for J pixels is provided at the beginning of the t line output period, and the subsequent effective image signal Dummy outputs for pixels are provided. Therefore, in Figure 1 (4
) When converting the image signal obtained by capturing a negative image of film FM using the imaging thread shown in ) into a λ value, the black part at the periphery of the negative image as shown in ) in Figure 1 of the film movement is converted into a λ value. Images are taken across both the dummy pixels and effective pixels shown in the figure, and the positive image of the black and white λ value shown in FIG. 1 (C) is sequentially shown in FIG. is now represented by a three-level image signal.In other words, as shown in Figure 3(C), the level difference that occurs between the dummy output level up to pixel number J- and the white level during effective output is In addition, a three-level image signal is obtained.

Therefore, if the ternary level analog image signal is converted into a time difference λ value as before, there will be a level change between the 3rd and 331st pixels.
As a result, the 3Jth and subsequent pixels are not determined to be accurately at the white level.

In the analog image signal in FIG. 3(C), the first level change detected by time difference λ value conversion is the 36th and 3rd.
Although it should be between the 77th pixel, a level change is detected between the 3.2nd and 33rd pixels, so
There was a drawback that all pixels after the 33rd were judged to be black.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, while maintaining the advantages of time difference-value conversion that does not require correction of output changes due to shading of the optical system, output fluctuations due to spatial frequency, etc., or γ correction, etc. An object of the present invention is to provide an analog signal lambda value converting device that can accurately convert only the range representing required information of an analog signal such as an image signal to an a value.

In other words, the λ value converting device of the present invention is based on the idea that it is more natural for a laser printer etc. to have the peripheral edge of a positive image as a white background. For unnecessary parts of the analog signal, such as the part of the analog image signal with 1. The signal is converted into an interval difference value by comparing it with the immediately preceding sample value.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of the configuration of the analog signal λ value conversion device of the present invention. In the illustrated configuration, an analog image signal from a photoelectric conversion element 1 consisting of a CCD or the like is led to a sample and hold circuit 3 via an amplifier 3, and a signal corresponding to the timing of a clock signal CLK/ from the oscillator/left is output. The level is held until the next sample value is obtained.

The output signal V of the sample and hold circuit 3 is guided to the input terminal of the differential amplifier and also to the delay element.
A delayed signal Vs 1 delayed by /sampling period is supplied to one input terminal of a differential amplifier j via a changeover switch /3 controlled by a counter circuit /B. In the past, the difference between adjacent sample values, such as the difference in signal level between adjacent pixels, was amplified and extracted by the differential amplifier 3, and the difference output signal VD was compared. It leads to one input terminal of comparator 7, and supplies reference voltages (+δ)// and (-δ)/λ to one input terminal and ten input terminals of comparator t and 7, respectively. As a result, if the difference output signal vD is greater than the reference voltage +δ, the comparator 6
If the difference output signal vD is smaller than the reference voltage -δ, a comparison output signal of a high logic level is obtained from the comparator 7.Furthermore, the difference output signal vD is the reference voltage -δ. When the voltage is between +a and -δ, comparators 6 and 7 both provide comparison output signals of a low logic level.

The comparison output signals of the comparators 6 and 7 are outputted to the oscillator /j
The signal is supplied to the set terminal and the set terminal of the flip-flop 10 through the gates ff and 9, which are opened at the timing of the clock signal CLK from the flip-flop 10, respectively. Therefore, as the difference output signal vD exceeds the reference voltage +6 and becomes lower than the reference voltage -1, 2f
An output signal converted to & is taken out from the 7 lip flop/θ.

Thus, the counter circuit /6 described above controls the changeover switch 13 as follows.

That is, when counting the click signals of the pixel period from the oscillator/left and converting the image signal having the configuration shown in the first figure into a λ value, for example, the sampled output voltage Ji, v8 from the sample and hold circuit 3 is Until it corresponds to the 3qth pixel, the changeover switch /3 is set to the comparison voltage source /l depending on the counting method.
Connect to the I side and supply the comparison voltage "ref to one input terminal of the differential amplifier 3, and convert the difference output voltage between the sequentially sampled output voltage v1 and the comparison voltage vref into a λ value in the same manner as described above, Further, for the m elements after the third group, the changeover switch /J is connected to the delay element q side, and the time difference λ value conversion is performed as described above.

Next, the comparison voltage vref is set as described above.

For example, as shown in FIG. 1, in a positive image reproduced from a negative film image, it is more natural to make the peripheral part a white background, so for the peripheral part of the positive image, the above-mentioned comparison voltage Vr@f is set to the same level as the sampled output voltage (1)8 for the part that is to be the heat level after converting to the a value.

Next, regarding the switching timing of the changeover switch 13, as is clear from the above, the oscillator/
The clock signal of the pixel period from J- is counted, and the changeover switch /3 is connected to the comparison voltage Vref side until the building block output voltage V becomes the output voltage for the 33rd pixel. When the output voltage V for the third pixel is obtained, the switch /3 is configured to be switched and connected to the delay element G side.

As is clear from the above description, according to the present invention, information necessary for the signal level of an analog signal is obtained, such as converting an analog image signal into a λ value when obtaining a positive image from a negative image such as a silver halide film. Accurate λ value conversion can be performed even if there is an unnecessary level change to represent the image, and there is no need to worry about the appearance of black frames around the edges of positive images or unsightly images, such as damage to the image, as in the past. It disappears.

[Brief explanation of the drawing]

Figures 1 (4) to (C) are diagrams sequentially showing the process of forming a positive image from a negative film image;
) are diagrams sequentially showing the process of forming a positive image signal, and Figures 3 to (C) are signal waveform diagrams sequentially showing the process of forming a positive image signal from the negative image signal. 1 is a block diagram showing an example of the configuration of an analog signal λ value converting device according to the present invention; FIG. LP...lamp, FM...film, LN...lens, CCD...photoelectric conversion element, l...CCD% 2m...amplifier, 3.
...sample hold circuit, G...delay element, S...differential amplifier, 6.7...comparator,
Z, D...and gate, 10...flip-flop, '//, /1...reference voltage source, 13...changeover switch, /ri...comparison voltage source, /S... oscillator,
/6... Counter circuit, /7,7g... Zener diode.

Claims (1)

[Claims] A sampling means for sequentially sampling an analog signal, a difference detection means for sequentially detecting a difference between a sample value by the sampling means and a comparison value, a comparison means for comparing the difference with a reference value, and a comparison by the comparison means. In the analog signal λ value converting device, the analog signal λ value conversion device has a level holding means for holding the signal level of the λ value signal at either a high or low λ value according to the result of the comparison value. Analog signal λ value converting device 1 characterized in that the comparison value is a constant value for the analog signal outside the predetermined range.