KR20020061241A - Analog/digital signal converting method - Google Patents

Abstract

PURPOSE: An A/D(Analog-to-Digital) signal converting method is provided to receive only one of white or black pattern signals, and to detect a maximum and a minimum of a luminance level for each signal, so as to detect whether noise is included and set a correct gain and offset through the appropriate compensation for the noise. CONSTITUTION: A black pattern signal is received for offset adjustment, and an offset value is initialized(S31). A maximum value and a minimum value are detected from a result of A/D conversion(S32). Whether an average value between the maximum and minimum values is larger than 0(zero) is decided(S33). If so, the offset value is increased by one step(S35), and the process of deciding whether an average value is larger than 0 is repeated. If an average value becomes smaller than 0, whether the average value is smaller than 0 is decided(S34). If smaller, the offset value is decreased by one step(S36), and the process of deciding whether an average value is smaller than 0 is repeated. If an average value is 0, the value is decided as an offset value(S37).

Description

Analog / Digital Signal Conversion Method {ANALOG / DIGITAL SIGNAL CONVERTING METHOD}

The present invention relates to an analog / digital signal conversion method, and more particularly, to an analog / digital signal conversion method for improving the performance of digital signal processing by converting an analog input signal accurately into a digital signal.

Currently, most electronic devices process data by digital methods, and since digital signals require a great deal of data, transmission is difficult where compression technology is not used.

For this reason, when the video signal is processed by the PC, the data is processed internally by a digital method, and when the video processed data is transmitted, it is transmitted by the analog method.

Therefore, when digital data is output in an analog manner as described above, in order to receive and process this signal, an operation of converting the analog signal back to digital is required. In general, the operation is performed by an analog-to-digital converter.

As such, accurate A / D conversion is a very important task in determining the accuracy of digital signal processing. In most analog-to-digital converters, the gain and offset are adjusted to adjust the signal from 0 to FF (8 bits). Case).

In this case, the offset becomes a reference level for distinguishing white from black, and the gain has a constant slope with respect to a signal value of a level higher than this offset.

Conventional analog-to-digital signal conversion method using gain and offset adjustment is largely three methods. The first method is to test several sets and find and use the average value of gain and offset. There is a disadvantage that it does not reflect the deviation of each set.

The second method is to set the gain and offset while measuring each set of signals directly with the test equipment, which is accurate but requires a lot of time and effort.

Next, the third method is a method of automatically setting gain and offset internally by a program method. This is a method recently used when an IC chip supporting communication is released, and the value processed by the A / D converter is used. It is a method of receiving input from a chip and checking it and setting gain and offset values based on it.

The method of automatically setting gain and offset by the third method, which is the third method, is performed by an algorithm as shown in FIGS. 3 and 4. Likewise, a pattern signal containing both white and black must be input.

Next, a method of adjusting the offset and the gain by receiving the pattern signal as described above will be described.

First, a method of adjusting an offset value of an analog-digital converter will be described with reference to the flowchart of FIG. 3.

First, in order to perform the offset adjustment, a pattern signal including white and black is input, an offset value is initialized (S11), and a minimum value of the result of the AD conversion is detected (S12).

In this case, the minimum value is a luminance level corresponding to the black pattern, and becomes '0' when it is completely black.

Therefore, if the minimum value is greater than '0' (S13), the offset value is increased by one step (S15), and the process of comparing and determining whether the minimum value is greater than '0' is repeated, and as a result, if the minimum value is smaller than '0', This time, if the minimum value is smaller than '0' (S14), if the minimum value is smaller than '0', the offset value is decreased by one step (S16) and the process of comparing and determining whether the minimum value is smaller than '0' is repeated. If the minimum value is equal to '0' as a result, the value is determined as an offset value (S17).

Next, the gain value adjusting method of the analog-digital converter will be described with reference to the flowchart of FIG. 4.

First, in order to adjust the gain, a pattern signal including white and black is input, the gain value is initialized (S21), and the maximum value of the result of the AD conversion is detected (S22).

In this case, the maximum value is a luminance level corresponding to the white pattern, and when the value is completely white, 'Max' becomes FF (when 8 bits).

Therefore, when the detected maximum value is greater than 'FF' (S23), the gain value is increased by one step (S25), and the process of comparing and determining whether the maximum value is greater than 'Max' is repeated, and as a result, the maximum value is' If the maximum value is smaller than 'Max', this time is compared (S24). If the maximum value is smaller than 'Max', the gain value is decreased by one step (S26). The process of comparing and determining whether the value is small is repeated. Accordingly, if the maximum value is equal to 'Max', the value is determined as a gain value (S27).

As described above, the gain and offset value adjusting method is a method of applying a signal pattern including both white and black, finding a minimum and maximum value among these signals, and finding a gain and an offset using this value. Is the minimum value and the white level is the maximum value.

However, in setting the gain and offset values using the maximum and minimum values, the noise is included in the maximum and minimum values of the signal actually obtained, but the noise component is not known at all, so this noise component is compensated for. You won't find any gain and offset values you can.

As such, when the gain and offset are not accurate, a problem of not being completely white and black at the time of inputting the white / black pattern as shown in FIGS. 1 and 2 occurs.

That is, the third method has the advantage of considering the difference of each set and easily setting the gain and offset values, but the maximum value is not the white value of the signal, but the value that contains positive noise in this value, Since the minimum value is not a black value but a negative noise on this value, there is a problem in that the level of black and white cannot be set correctly by this method.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and by receiving only one pattern signal of white or black, finding a maximum value and a minimum value of the luminance level for each of them, the noise component is included. It is an object of the present invention to provide an analog / digital signal conversion method capable of detecting whether or not there is a signal, and appropriately compensating for the noise component to enable accurate gain and offset setting.

1 is an exemplary view showing a screen for explaining a state when the offset value adjustment is not properly performed in the analog-to-digital converter.

2 is an exemplary view showing a screen for explaining a state when the gain value adjustment is not properly performed in the analog-to-digital converter.

3 is a flowchart illustrating a method of adjusting an offset value in a conventional analog-to-digital converter.

4 is a flowchart illustrating a gain value adjusting method in a conventional analog-to-digital converter.

Fig. 5 is a flowchart showing a method of adjusting an offset value in an analog-digital converter by the present invention.

6 is a flow chart shown to explain a gain value adjusting method in an analog-digital converter by the present invention.

According to the present invention for achieving the above object, in the analog-to-digital converter, after initializing the offset value to adjust the offset value, receiving a signal of pure black pattern only, the minimum value of the luminance level from the result of the AD conversion of the signal Detecting a maximum value and a maximum value to obtain an average value thereof; Until the average value is equal to the minimum value of the analog-to-digital converter, it is characterized in that the second step of setting the offset value by repeatedly increasing or decreasing the step of the offset value.

In addition, the present invention, in the analog-to-digital converter, after initializing the gain value for adjusting the gain value, receives a signal of pure white pattern only, detects the minimum value and the maximum value of the luminance level from the result of the AD conversion of the signal; A first step of obtaining the average value; Until the average value is equal to the maximum value of the analog-to-digital converter, a second step of setting the gain value is repeated by repeatedly increasing or decreasing the step of the gain value.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of not accurately setting the levels of black and white due to noise in the above-described automatic adjustment method for setting the gain and offset, so that the automatic adjustment can be made more accurately and quickly. To provide.

According to the present invention, a gain and an offset are set by inputting one pattern of white or black, respectively, without using a pattern in which white and black are included.

Of course, knowing more about noise in addition to the maximum and minimum values makes it easier to compensate for offsets and gains, but this problem cannot be solved if the IC itself does not support it.

Therefore, in the present invention, unlike the conventional method, since only one pattern signal of white or black is input, the maximum value and the minimum value of the luminance level are found for each of them, and thus it is possible to detect whether a noise component is included. Appropriate compensation can be made for noise components, enabling more accurate gain and offset settings.

That is, when a signal pattern of white or black is applied to detect the maximum value and the minimum value of the luminance level for the signal, if the signal does not contain a noise component, the two values are the same, and the noise component is included. If so, the two values will be different.

At this time, the maximum value is a value obtained by adding a noise signal in both directions to an original signal level, and the minimum value is a value obtained by adding a noise signal in a negative direction.

In other words, when a signal having only one luminance level is applied, the difference between the maximum value and the minimum value is purely a noise. The noise received while the input signal is transmitted to the A / D converter is randomly generated noise. .

Here, since the randomly generated noise is not a directional noise, the noise component in the positive direction and the noise component in the opposite direction are almost similar.

Therefore, if the average value of the maximum value and the minimum value of the luminance level is obtained, the value is almost close to the original luminance level value for black or white. That is, the average value of the two values is the level of the signal compensated for the noise component.

Then, the offset value adjustment method of the analog-digital converter according to the present invention will be described with reference to the flowchart of FIG.

First, in order to perform the offset adjustment, the black pattern signal is input, the offset value is initialized (S31), and the minimum and maximum values of the result of the AD conversion are detected (S32).

In this case, the minimum value is a luminance level corresponding to the black pattern, and is '0' in the case of perfect black, and '0' in the case of the perfect black. Therefore, the average of the minimum and maximum values also becomes '0'.

Therefore, when the average value is larger than '0' (S33), the offset value is increased by one step (S35), and the process of comparing and determining whether the average value is larger than '0' is repeated, and as a result, when the average value is smaller than '0', At this time, comparing the average value is smaller than '0' (S34), if the average value is smaller than '0', the offset value is decreased by one step (S36) and the process of comparing and determining whether the average value is smaller than '0' is repeated. As a result, when the average value is equal to '0', the value is determined as an offset value (S37).

Next, a gain value adjusting method of the analog-digital converter according to the present invention will be described with reference to the flowchart of FIG. 6.

First, in order to adjust the gain, a white pattern signal is input, the gain value is initialized (S41), and the minimum and maximum values of the result of the AD conversion are detected (S42).

In this case, the maximum value is a luminance level corresponding to a white pattern. In the case of complete white, 'Max' becomes FF (when 8 bits) and the minimum value becomes FF in case of complete white. Therefore, the average of the minimum and maximum values should also be 'FF'.

Accordingly, if the detected average value is larger than 'Max' (S43), the gain value is increased by one step (S45), and then the process of comparing and determining whether the average value is larger than 'Max' is repeated, and as a result, the average value is' If the average value is smaller than 'Max', this time, if the average value is smaller than 'Max', the gain value is decreased by one step (S46), and the average value is smaller than the 'Max'. The process of determining is repeated, and when the average value is equal to 'Max', the value is determined as a gain value (S47).

In other words, since the offset adjustment is to obtain the basic level, the maximum and minimum values are read and the average value of the two values is obtained when the signal of the black pattern is applied.

Next, it is checked whether the average value is 0 (base level), otherwise it is not an accurate offset value, and the above process is repeated after adjusting the offset again.

Accordingly, if the average value is larger than the basic level (0), this means that the offset is low, so that normal black is not output as shown in FIG. In this case, the offset value must be raised by a certain amount.

On the contrary, if the average value is lower than the base level (0), it means that the offset is high. Therefore, since the signal of the low level is eliminated, the offset value should be lowered at this time.

On the other hand, when adjusting the gain, a white pattern must be input and the process is performed in the same manner as when the offset is set. However, since the maximum value is affected by the offset, which is the basic level, the adjustment should be performed after the offset adjustment is finished.

As described above, the analog-to-digital signal conversion method of the present invention receives only one pattern signal of white or black and finds the maximum value and the minimum value of the luminance level for each of them, thereby detecting whether a noise component is included. This makes it possible to properly compensate for the noise component so that accurate gain and offset settings can be made.

Claims (6)

In the analog-to-digital converter, a method of initializing the offset value for adjusting the offset value and receiving a signal of pure black pattern only, detecting the minimum and maximum values of the luminance level from the result of the AD conversion of the signal, and obtaining the average value. Step 1; And a second step of setting an offset value by repeatedly increasing or decreasing the step of the offset value until the average value is equal to the minimum value of the analog-to-digital converter. . The method of claim 1, further comprising: a first step of determining whether the minimum value of the analog-to-digital converter in the second step is '0' and the average value obtained by the minimum value and the maximum value is greater than '0'; A second step of repeating the first step by increasing the offset value by one step when the average value is greater than '0'; A third step of comparing, when the average value is smaller than '0' by the second step, whether the average value is smaller than '0'; When the average value is smaller than '0', the offset value is decreased by one step, and the fourth value of repeating the third process is set to set the offset value when the average value is equal to '0'. Analog-to-digital signal conversion method. The method of claim 2, wherein the step of increasing or decreasing the offset value may be implemented in reverse depending on a circuit implementation method. In the analog-to-digital converter, a signal for initializing a gain value for gain adjustment and receiving a signal of pure white pattern only, and detecting the minimum value and the maximum value of the luminance level from the result of the AD conversion of the signal to obtain the average value. Step 1; Until the average value is equal to the maximum value of the analog-to-digital converter, the second step of setting the gain value by repeating the step of increasing or decreasing the step of the gain value, characterized in that consisting of a second step Way. The maximum value of the analog-to-digital converter in the second step is the maximum value (Max) by the resolution, and the average value obtained by the minimum value and the maximum value detected in the white pattern signal is 'Max'. A first step of judging whether or not it is greater; A second step of repeating the first step by increasing the gain value by one step when the average value is greater than 'Max'; A third step of comparing, when the average value is smaller than 'Max' by the second step, whether the average value is smaller than 'Max'; When the average value is smaller than 'Max', the offset value is decreased by one step to set the gain value when the average value is equal to 'Max' by the fourth process of repeating the third process. Analog-to-digital signal conversion method. 6. The method of claim 5, wherein the step of increasing or decreasing the gain value may be reversed depending on the circuit implementation.