JP3232950B2 - Video type identification device, automatic aspect ratio identification device and television receiver using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video type identification device for identifying a video type of information contained in a video signal input to a television receiver or a video signal output from a recording medium such as a video tape recorder. , An aspect ratio automatic identification device that automatically identifies an aspect ratio from its video type, and a television receiver that incorporates the aspect ratio automatic identification device and automatically performs optimal display adapted to an input video signal. It is.

[0002]

2. Description of the Related Art In recent years, displays having an aspect ratio of 16: 9, such as wide-screen television receivers and high-vision television receivers, have become widespread. In order to use this 16: 9 display effectively, it is necessary to determine the aspect ratio of the video signal and switch the display range. Therefore, an aspect ratio identification device for switching a display range is regarded as important.

FIG. 20 is a block diagram showing a conventional aspect ratio discriminating apparatus. Reference numeral 17 denotes a remote controller that stores the aspect ratio determined by the user and transmits information to the microcomputer. The microcomputer 18 outputs a signal relating to the video start position and the vertical expansion rate according to the information transmitted from the remote controller 17.

[0004] The operation of the aspect ratio discriminating apparatus configured as described above will be described below with reference to FIG.

First, the user looks at the image displayed on the screen and determines whether the image is 4: 3 image, cinema image (5: 3) or wide image (16: 9). In the case of a cinema video, the cinema button on the remote controller 17 is pressed as shown in FIG. 21 and transmitted to the microcomputer 18 to enlarge the video in the vertical direction. As in the case of the cinema image, the wide image is expanded in the vertical direction by pressing the wide button of the remote controller 17 and transmitting it to the microcomputer 18 as shown in FIG.

[0006]

However, the above configuration has a problem that the operation of the television receiver is complicated because the user has to determine the aspect ratio by himself.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides an automatic aspect ratio identification apparatus for automatically identifying the aspect ratio of a video signal by a television receiver, thereby improving operability for a user.

[0008]

In order to achieve the above object, the present invention detects a luminance signal level for each first predetermined period unit for sampling an input video signal, and generates a distribution of each luminance level occurrence frequency. Histogram generation means for generating a histogram to be shown, and each luminance level occurrence frequency for each second predetermined time period in order to compare the histogram shape of the output of the histogram generation means for each second predetermined time, such as for each scanning line Comparison means for classifying the distribution into a plurality of image types; edge detection means for detecting a change point of the image type such as a change from a black image to an image from the output of the comparison means; and different images detected by the edge detection means A counter for issuing a timing signal for specifying the relationship between the change point to the type and the temporal position of the input video signal, and the video type of the edge detection means A time filter that generates a position signal in the video signal at the first change point when the first change is detected and the second change as the next video type change is detected for a predetermined period of time. A video type identification which can obtain a video type of information contained in an input video signal, a change point of the video type, and a temporal positioning signal of the input video signal at the change point from an output of the time filter. Provide equipment.

Further, the aspect ratio of the image is automatically obtained from the ratio of the image occupied in the screen of one frame or one field unit from the output of the video type identification device and the position of the change point of the video type. The present invention provides an aspect ratio automatic identification device provided with the above.

Furthermore, the aspect ratio automatic discrimination device is incorporated, and based on the output, an input video signal such as an aspect conversion, a vertical position shift, and a subtitle shift process for display on a display means such as a CRT or a liquid crystal display panel. A television receiver for automatically performing an optimal display according to the information of the television receiver.

[0011]

According to the present invention, a histogram is formed in a predetermined time unit such that the luminance signal level of an input video signal is line by line, and the type of information contained in the input video signal is obtained from the shape of the histogram. ing. A plurality of types are set as video types, and a histogram obtained from an input video signal is classified into one of the video types. The video types are classified so that the information sent by the input video signal can be identified as having what aspect ratio the image has. Therefore, the aspect ratio is automatically obtained from the change point. I can do it.

More specifically, three histograms separated by the slice levels S and T are generated for each line from the luminance signal Y, and the obtained histogram is input to a comparison circuit. Judgment as black, image, or subtitle, edge detection circuit detects a line that changes from black to image, image to black, and subtitle to black, and a time filter that changes black to image and image to black By determining whether is stable over time,
An image signal start position, an image signal end position, and a subtitle end position can be detected. From this, it is possible to obtain an optimum image display by obtaining the aspect ratio of the image and enlarging and displaying the image in accordance with the aspect ratio of the display screen of the display means.

[0013]

【Example】

(Embodiment 1) First, an aspect ratio automatic identification apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 4, and 5. FIG.

FIG. 1 is a block diagram of an automatic aspect ratio identification apparatus according to a first embodiment of the present invention.
Reference numeral 1 denotes a comparison circuit which outputs a signal Q1 indicating Y <S when the luminance signal Y is lower than a certain slice level S, and a signal Q3 indicating Y> T when the luminance signal Y is higher than a certain slice level T.
Otherwise, a signal Q2 indicating S ≦ Y ≦ T is output. Here, for example, the black level of the image signal is set as the slice level S, and the white level of the image signal is set as the slice level T. 2, 3 and 4 are counters, the counter 2 counts the signal Q1, the counter 3 counts the signal Q2, and the counter 4 counts the signal Q3.

Reference numeral 6 denotes a comparison circuit, which is the output N of the counter 2
If 1 is larger than a constant A, the signal CP1 is set to the H level,
If the output N1 of the counter 2 is larger than a certain constant B, the output N2 of the counter 3 is smaller than a certain constant C, and the output N3 of the counter 4 is larger than a certain constant D, the signal CP
3 is at H level, otherwise the signal CP2 is at H level. For example, if the total number of sample points of the luminance signal Y is 256, the constants A are 25,
0, constant B is 128, constant C is 100, and constant D is 5.

Reference numeral 7 denotes a counter having a horizontal synchronization signal counting from 0 for each field as a clock input.

Reference numeral 8 denotes an edge detection circuit which monitors three output levels of the comparison circuit 6 and uses the output value of the counter 7 as a signal m when the signal output as the H level changes from the signal CP1 to the signal CP2. When the signal output and output as H level changes from signal CP2 to signal CP1, the output value of counter 7 is output as signal n, and the signal output as H level is output from signal CP3 to signal CP1.
, The output value of the counter 7 is output as a signal l. The signals m, n, l include, for example, 58, 226, 2
A value of 40 is output for each.

Reference numeral 9 denotes a time filter, which outputs the signals m and n as they are as the signals M and N when the signals m and n do not change for a certain period or more, and otherwise inputs the values. Regardless of the above, the value signals m ′ and n ′ held inside the filter are output as the signal M and the signal N.

The operation of the automatic aspect ratio discriminating apparatus according to the first embodiment of the present invention configured as described above will be described below with reference to FIGS. 2, 3, 4 and 5.

First, the input luminance signal Y is converted by the comparison circuit 1 into Y <S, S ≦ Y ≦ according to the signal level of the luminance signal Y.
T, Y> T. The counters 2, 3, and 4 accumulate their outputs for each line to generate three histograms as shown in FIG. Next, the comparison circuit 6 classifies the histograms obtained by the counters 2, 3, and 4 into three types: a black histogram (CP1), an image histogram (CP2), and a subtitle histogram (CP3). That is,
When the luminance signal Y in one line period is concentrated on the black level, the distribution is concentrated on the portion of the histogram where Y <S, and a histogram (CP1) as shown in FIG. 2A is obtained. , The distribution of the luminance signal Y is dispersed in three places of Y <S, S ≦ Y ≦ T, Y> T in the histogram, and the histogram (CP) as shown in FIG.
2) is obtained, and when the luminance signal Y in one line period is concentrated on the black level and the white level, the distribution of the histogram is concentrated on the portion of Y <S and Y> T, and FIG. The fact that a histogram (CP3) as shown is obtained is used.

Using the classified data, the histogram of the image (CP1) is changed from the histogram of the black (CP1).
By outputting the value of the counter 7 when changing to 2), a signal m (hereinafter referred to as a line m) indicating the upper position E of the image of the letterbox signal is obtained. By outputting the value of the counter 7 when changing to the histogram (CP1), a signal n (hereinafter, referred to as a signal indicating the image lower position F of the letterbox signal).
Line n), and a subtitle histogram (CP
By outputting the value of the counter 7 when the histogram changes from 3) to the black histogram (CP1), a signal 1 (hereinafter, referred to as a line 1) indicating the subtitle lower position G of the letterbox signal is obtained. The edge detection circuit 8 detects as shown in FIG.

Further, the detected lines m and n are inputted to the time filter 9. FIG. 4 shows an embodiment of the time filter 9. The input I is an example of the lines m and n, and is first latched by the flip-flop 19 field by field. The coincidence detection circuit 20 compares the input I with the output of the flip-flop 19, and outputs an H level if they coincide, and outputs an L level otherwise. The flip-flops 21, 22, and 23 delay the output of the coincidence detection circuit 20 by one field, two fields, and three fields, respectively.

The AND circuit 24 performs an AND operation on the outputs of the coincidence detection circuit 20 and the flip-flops 21, 22, and 23, and the output of the AND circuit 24 becomes H level only when all of them are at H level. The output of the AND circuit 24 becomes a load / hold pulse of the flip-flop 25, and
Flip-flop 1 only when the output of circuit 24 is at H level
9 is latched by flip-flop 25.

FIG. 5 is a timing chart of the time filter 9 shown in FIG. As shown in FIG. 5, FIG.
It is a time filter for the field and the input data I
Output only when the same data continues for more than 5 fields
Changes.

Thus, the recognition of the image type is completed,
The letter box signal is recognized, and the position and size of the image portion can be obtained.

Next, the aspect ratio is recognized by detecting the upper image position E and the lower image position F of the letterbox signal, and the image is enlarged in the vertical direction as an optimal image display method generally performed as the next operation. The image display start position when trying to do so, and the vertical enlargement ratio (220 / (m−
n)) can be calculated. For example, when the image upper position m is 58 and the image lower position n is 226, the image start position when the image is enlarged in the vertical direction is 58 lines, and the vertical enlargement ratio at that time is 220 / (226-58). =
It becomes 1.31 times. Here, E and F are geometrical positions,
m and n indicate the electrical position, that is, the number of the scanning line.

(Embodiment 2) Next, an aspect ratio automatic identification apparatus according to a second embodiment of the present invention will be described with reference to FIG. An object of the second embodiment is to enhance the detection accuracy of the upper image position E, the lower image position F, and the lower caption position G of the letterbox signal by detecting the color signal.

FIG. 6 is a block diagram showing an aspect ratio automatic identification device according to the second embodiment. The difference from the first embodiment is that the color signal detection circuit 10 is provided and its output is used as an input to the comparison circuit 1, that is, the operation when a color signal is detected.

When the chrominance signal is detected by the chrominance signal detection circuit 10, the comparison circuit 1 determines that S ≦ Y even if the relationship between the luminance signal Y and certain slice levels S and T is Y <S or Y> T.
The counter 3 outputs the signal Q2 as ≦ T. If no color signal is detected, the comparison circuit 1 operates as in the first embodiment. Because, in the three distributions Y <S, S ≦ Y ≦ T, Y> T of the histogram, Y <S indicates that the luminance signal is at the black level, and Y> T indicates that the luminance signal is at the white level. It is because it represents.

The non-picture portions above and below the letterbox signal are black, and when a subtitle is inserted in the non-picture portion, the subtitle is displayed in most cases in white. Therefore, when a color signal is detected, the signal should be judged as an image, not a non-picture part or a subtitle of the letterbox signal.

In this embodiment, the aspect ratio automatic identification device
In the histogram distribution, when the Y <S (signal Q1) portion is larger than a certain constant A, black (no image portion) and Y <S
(Signal Q1) part is larger than a certain constant B, S ≦ Y ≦ T
When the (signal Q2) portion is smaller than a certain constant C and the Y> T (signal Q3) portion is larger than a certain constant D, the subtitle is determined. Therefore, when a color signal is detected, the luminance signal Y and a certain slice level S, Even if the relationship with T satisfies Y <S, Y> T, the histogram is counted as S≤Y≤T (image portion) in the histogram, so that the black histogram detected by the comparison circuit 6 and the subtitle The histogram detection accuracy can be increased.

As described above, according to the second embodiment, the image upper position E, the image lower position F, and the subtitle lower position G of the letterbox signal can be detected with higher accuracy.

(Embodiment 3) Next, an automatic aspect ratio identification apparatus according to a third embodiment of the present invention will be described with reference to FIGS.

FIG. 7 is a block diagram of an automatic aspect ratio identification device according to a third embodiment of the present invention. An object of the third embodiment is to prevent erroneous detection of an upper image position and a lower image position by detecting darkness of the entire video signal. The difference from the first embodiment is that a comparison circuit 11 compares the output of the counter 2 with a constant R, a counter 12 that receives the output of the comparison circuit 11 as an input, and a comparison circuit that compares the output of the counter 12 with a specified value V. This is the operation when the circuit 13 is provided and when the output CP4 of the comparison circuit 13 becomes H level.

The comparison circuit 11 compares the output N1 of the counter 2 with a certain constant R, and if N1> R, the level is H level, and N1 ≦ N1.
If R, L level is output. This means comparing the constant R with the state of the (luminance signal Y) <(slice level S) part of the three distributions of the histogram, and N1
If> R, an H level is output, and it is determined that the line is dark. Assuming that the total number of sample points in one line is 256, for example, 200 is input as the constant R.

Next, the output of the comparison circuit 11 is counted by a counter 12 using the horizontal synchronization signal as a clock input. The integrated value k of the counter 12 indicates how many lines are determined to be dark in one field. Further, the integrated value k of the counter 12 is compared with a certain specified value v by the comparing circuit 13. If k> v, the output CP4 of the comparing circuit 13 becomes H level, and k ≦ v
Then, CP4 becomes L level.

The specified value v is a value that determines how many lines in one field are determined to be dark when the entire video signal is determined to be dark. For example, a value of 128 is input as the specified value v.

When the output of the comparison circuit 13 is at the H level, the time filter 9 again outputs the values of M and N output immediately before, regardless of the output of the edge detection circuit 8. When the output of the comparison circuit 13 is at L level, the time filter 9 operates in the same manner as in the first embodiment. This is a countermeasure against the fact that when the entire video signal of one field is dark, an erroneous image upper position m and an image lower position n are likely to be detected.

With this operation, when the video portion of the letterbox video is dark as shown in FIG. 8, the detection of the erroneous upper image position E 'and the lower image position F' is prevented, and the correct upper image position detected earlier is prevented. The signal M indicating the position and the signal N indicating the lower position of the image are stored in the time filter 9 and output to the outside.

As described above, according to the third embodiment, it is possible to prevent erroneous detection of the automatic aspect ratio identification device when the entire video signal is dark.

Although the third embodiment has been described based on the first embodiment, it is needless to say that the third embodiment can be applied to the second embodiment.

(Embodiment 4) The purpose of the fourth embodiment is to detect the darkness of the whole video signal to prevent erroneous detection of the upper image position and the lower image position, similarly to the third embodiment. That is.

FIG. 9 is a block diagram of an automatic aspect ratio identification apparatus according to a fourth embodiment of the present invention. The difference from the first embodiment is that the luminance signal Y is input and the APL detection circuit 14 for detecting the average luminance level of the entire video signal of one field is compared with the output N4 of the APL detection circuit 14 and a certain prescribed value w. And the comparison circuit 15
This is the operation when the output CP5 of H. becomes high level.

The APL detection circuit 14 detects the average luminance level of the video signal of one field. Next, the comparison circuit 15 compares the output N4 of the APL detection circuit 14 with a specified value w. If N4 <w, the output CP5 of the comparison circuit 15 goes high, and if N4 ≧ w, CP5 goes low.
That is, the average luminance level N4 of the video signal of one field
When the value is smaller than a certain specified value w, it is determined that the entire video signal is dark, and the output CP5 of the comparison circuit 15 goes to the H level. When the value is equal to or larger than the specified value w, it is determined that the video signal is bright, and the output CP5 of the comparison circuit 15 becomes L level. AP
When the output N4 of the L detection circuit 14 is output in 8 bits, the specified value w is, for example, a value of 100.

When the output of the comparison circuit 15 is at the H level, the time filter 9 again returns the values indicating the image upper position E and the image lower position F (FIG. 8) output immediately before, regardless of the output of the edge detection circuit 8. Output. When the output of the comparison circuit 15 is at the L level, the time filter 9 operates in the same manner as in the first embodiment. This is a countermeasure against the fact that when the entire video signal of one field is dark, it is highly likely that an erroneous upper image position E ′ and lower image position F ′ (FIG. 8) are detected.

By this operation, when the image portion of the letterbox image is dark as shown in FIG. 8, incorrect detection of the upper image position E 'and the lower image position F' is prevented, and the correct upper image position detected before that is detected. The signals corresponding to the position E and the image lower position F are held and output to the outside.

As described above, according to the fourth embodiment, it is possible to prevent erroneous detection of the automatic aspect ratio identification device when the entire video signal is dark. The difference from the third embodiment lies in the method of detecting the darkness of the entire video signal.

Although the fourth embodiment has been described based on the first embodiment, it is needless to say that the fourth embodiment can be applied to the second embodiment.

(Embodiment 5) The purpose of the fifth embodiment is to specify the existence ranges of the upper portion of the image, the lower portion of the image, and the lower portion of the caption of the letterbox signal, respectively, and to set the incorrect upper portion position and the lower portion position of the image. , To prevent detection of the subtitle lower position.

FIG. 10 is a block diagram of an automatic aspect ratio identification apparatus according to a fifth embodiment of the present invention. The difference from the first embodiment is that the outputs m, n, l of the edge detection circuit 8 are different.
And a verification circuit 1 having certain prescribed values α, β, γ, and δ as inputs.
6 and the operation when the inputs m, n, l of the verification circuit 16 and the outputs m ″, n ″, L are different.

The verification circuit 16 receives the outputs m, n, and l of the edge detection circuit 8 and detects the edges m and n a plurality of times (for example, m) during the video signal period of one field.
1, m2, n1, n2), the value of m ″, n ″ detected immediately before is output again. This is, for example, FIG.
As shown in (a), the video part of the letterbox signal is also
This phenomenon occurs for an image in which a black band similar to the upper and lower non-image portions exists.

Further, the existence ranges of m and n are determined as shown in FIG. 11 by prescribed values α and β, and γ and δ, respectively, and α <m <β,
If any of γ <n <δ holds, the value of m ″, n ″ detected immediately before is output again. The normal video display range is 252 from the 32nd line out of 262.5 scanning lines.
If it is up to the line, α, β, γ, and δ are each 3
Values such as 2, 132, 133, and 252 are taken.

Further, the relationship between m, n, and l is such that m <n <l holds when a correct edge is detected. In other cases, the value of the immediately preceding detected value m ″, n ″, l is replaced by the value of m ″, n ″, l. Output again. When all three constraints are satisfied, the values m, n, and l are output as m ", n", and l as they are. The time filter 9 operates similarly to the first embodiment.

By this operation, when the letterbox image is in the condition as shown in FIG.
The lower position F 'of the image is detected, the malfunction of the automatic aspect ratio identification device is reduced, and the reliability can be improved.

Although the fifth embodiment has been described based on the first embodiment, it is needless to say that the fifth embodiment can be applied to the second, third or fourth embodiment.

(Embodiment 6) An object of the sixth embodiment is to continue to detect an accurate upper image position and lower image position for a letterbox signal.

FIG. 13 is a block diagram of an automatic aspect ratio identification apparatus according to a sixth embodiment of the present invention. A feature point different from the first to fifth embodiments is that a vertical filter 26 for removing a singular point and an enable / disable control circuit 2 are provided.
7. Point comparison circuit 13 provided with selector 30 and comparison circuit 2
9 is externally controlled by the selector 30.

FIG. 14 is a block diagram of the vertical filter 26 used in the sixth embodiment of the present invention. This vertical filter 26 is used to remove a singular point of one line. The comparison circuit 6 creates a histogram for each line with respect to the video signal, and determines whether each line is “black”, “image”, or “caption”.
1, CP2 and CP3 are output and input to the vertical filter 26. Since this is input in three bits, the data is encoded into two bits by the encoder 31 in order to facilitate the subsequent processing. FIG. 15 is a table showing an example of encoding.

After encoding in this manner, the EX-NOR circuit 26 compares the current data (output of the encoder 31) and the data two lines before (output of the flip-flop 33) bit by bit. If they match, the data of the previous line (output of flip-flop 33) is output, and if they do not match, the data of the previous line (output of flip-flop 32) is output as it is. The output of the selector 34 is latched by the flip-flop 35, and finally the signal is converted by the decoder 38 to the original 3-bit signals (CP1 ', CP2',
CP3 ') format and output to the outside. FIG. 16 shows a timing chart of the vertical filter 26. As shown in the timing chart of FIG. 16, this vertical filter 26 is used to remove a singular point when one line of the singular point occurs and generate smooth data.

Enable / Disable Control Circuit 27
Receives the output M (upper image position E) of the counter 7 and the time filter 9 counting sequentially from 0 and outputs an H level until the output of the counter 7 changes from 0 to M, and otherwise outputs L level. Output level. While the output of the enable / disable control circuit 27 is at the H level, the counter 28
Is enabled, and counts how many times the output CP1 'of the vertical filter 26 goes high during that period. CP1 '
Means that the line is determined to be black, and when this is counted until the output of the counter 7 changes from 0 to m ", the number of black lines in the non-image area on the letterbox signal is determined. It can be seen whether there is a determined line.

The comparison circuit 29 outputs the output BN of the counter 28
The number of lines determined to be black in the non-image area is compared with the value of a certain constant Q. When BN> Q, the output goes high, and when BN ≦ Q, the output goes low. If a certain constant Q is set to a value of, for example, 3, the output of the comparison circuit 29 becomes L level when four or more lines are determined to be black in the non-picture part on the letterbox signal.

The outputs of the comparison circuits 13 and 29 are controlled by, for example, an external signal zon output from a microcomputer. When the external signal zon is at L level, the output of the comparison circuit 13 is input to the time filter 9 when the external signal zon is at H level. When the output of the selector 30 is at the H level, the time filter 9 again outputs the values of m ″ and n ″ output immediately before, regardless of the output of the verification circuit 16.

When the output of the selector 30 is at the L level, the time filter 9 operates in the same manner as in the first embodiment. However, as for l for detecting the subtitle position, regardless of the value of the output SO of the selector 30, the time filter 9 outputs l as it is when the same value is input as l 'for a certain fixed time or more, Otherwise, the previously detected value is held.

When the aspect ratio is 4: 3 video, by controlling the external control signal zon to L level, the darkness of the whole video signal of one field is detected. The detected upper image position and lower image position are held, and an accurate detection value is output when the entire video signal is bright. In the case of letterbox video, by controlling the external signal zon to the H level, only the darkness of the upper non-image portion is detected, and the non-image portion retains the image upper position and the image lower position detected earlier. Thus, stable detection information can be output for each video.

(Embodiment 7) The purpose of the seventh embodiment is to continue to accurately detect the upper image position and the lower image position of a letterbox video as in the sixth embodiment.

FIG. 17 is a block diagram of an automatic aspect ratio identification apparatus according to a seventh embodiment of the present invention. What differs from the sixth embodiment is the control method of the enable / disable control circuit 27 and its operation.

Enable / Disable Control Circuit 27
Receives the output of the counter 7 counting sequentially from 0, the output M of the time filter 9 (indicating the image upper position E) and N (indicating the image lower position F), and outputs the counter 7 from M to M + P, N An H level is output until −P changes to N, otherwise an L level is output. While the output of the enable / disable control circuit 27 is at the H level, the counter 28 is enabled and counts how many times the output CP1 'of the vertical filter 26 goes to the H level during that period.

The comparison circuit 29 compares the output BN of the counter 28 with the value of the constant Q. The output goes high when BN> Q, and goes low when BN ≦ Q. If the constants P and Q are set to values of, for example, 10, 0, it is determined that the letterbox signal is black between the upper 10 lines of the image and the lower 10 lines before the lower line of the image. The presence or absence of the detected line is detected by counting by the counter 28, and if at least one line is determined to be black, the output of the comparison circuit 29 becomes H level.

As described above, in the case of a letterbox video, by detecting the darkness inside the detected boundary line,
Erroneous detection of the upper image position and the lower image position of a letterbox image in which only the inside of the boundary is dark is reduced, and the detection accuracy is increased.

(Embodiment 8) Embodiment 8 is a television receiver incorporating an automatic aspect ratio identification device, and FIG. 18 is a block diagram showing the configuration thereof.

The input signal received from the external antenna is selected by the reception tuner 41, and is input as an analog video signal.
The signal is input to the first signal processing unit 42. The first signal processing unit 42 converts the input analog signal into a digital signal by A
/ D conversion unit 43, and converts the digitalized video signal into 3
The processing of the color signal and the luminance signal such as the dimensional YC separation
, A self-aspect unit 45 having the function of an automatic aspect ratio identification device for detecting the aspect ratio of an input video signal from a luminance signal, a color signal demodulation unit 46, and a memory such as a subtitle process. And a caption processing unit 47 that processes the subtitles using the subtitle processing unit 49. The signal output of the first signal processing unit 45 is output to the drive unit 54 via a second signal processing unit 52 having image quality improvement and D / A conversion functions.
The display unit 55 such as an RT is driven. On the other hand, the synchronization is separated by the sync separation unit 50 based on the output from the YC processing unit 44 of the first signal processing unit 42, and a synchronization signal is supplied to the drive unit 54. The microcomputer 53 controls each circuit of each of the above-described circuit configurations by a signal input / output via the bus 56. Since the control system of the microcomputer 53 becomes very complicated when all the systems are displayed, the other parts are omitted only for those relating to the automatic aspect ratio identification device.

Next, an operation for automatically identifying an aspect and performing an appropriate image display using the result will be described. When the input video signal is a signal in the letter box format with an aspect ratio of 4: 3, the display unit 55 having a display screen with an aspect ratio of 16: 9 without performing the aspect processing as it is.
19A is shown in FIG. The display unit 55 has a so-called wide screen having an aspect ratio of 16: 9 as a display frame as shown in the figure, in which a letterbox image displayed by a scanning line having an aspect ratio of 4: 3 is displayed. . In addition to this display mode, there is also a mode as shown in FIG. 19B in which scanning lines are scanned to fill the display frame.

The operation in the case of incorporating the automatic aspect ratio discrimination device of the above-described embodiment in the case of such a signal will be described. A luminance signal, which is one of the outputs of the YC processing unit 44 of the first signal processing unit 42, is input to the self-aspect unit 45. The self-aspect unit 45 has a function of an automatic aspect ratio identification device, samples the luminance level of the input luminance signal, forms a luminance histogram for each scanning line, and identifies the image type from the shape of the histogram. The upper image position E and the lower image position F are detected as boundary points of different video types as shown in FIG.
The upper image position E and the lower image position F are determined by the YC processing unit 44.
The vertical position is detected as the time from the vertical synchronizing signal of the synchronizing signal from.

The above detection signal is input to the subtitle processing unit 47 and used as a signal for subtitle processing when there is a subtitle in the black portion of the letterbox video, and is also input to the microcomputer 53 via the bus 56 and Is input to the drive unit 54 as a control signal. Drive unit 5
In 4, a synchronous deflection output signal and an RGB output signal are output to drive the display unit 55, but the deflection amplitude is changed to enable enlarged display as needed. The ratio related to the vertical amplitude in the amplitude expansion is determined using the output signal from the self-aspect unit 45. In other words, the microcomputer 53 is programmed to determine how to display the most suitable image based on the correspondence between the content of the input video signal and the shape (aspect ratio) of the display frame of the display unit 55. Therefore, according to the control signal from the microcomputer 53, the horizontal amplitude is first expanded to fill the display frame because the horizontal amplitude is a letterbox signal.

Next, the vertical position and the aspect ratio of the image are calculated based on the information of the image upper position E and the image lower position F from the self-aspect section 45, and the vertical position movement and the vertical amplitude enlargement ratio are calculated based on the calculation result. It is automatically calculated and output as the optimal deflection current.

As a result, as shown in FIG. 19 (b), the image portion of the letterbox signal is enlarged to fill the display frame of the display unit 55, and an optimal display according to the image can be achieved. As described above, even in a display having a display unit regardless of the television receiver, a microcomputer programmed to output a control signal capable of optimal display from the relationship between the shape of the display frame and the input video signal. Incorporating the aspect automatic identification device provided with, automatically enables optimum display for any input video signal.

[0077]

As described above, the picture type discriminating apparatus according to the present invention, the automatic aspect ratio discriminating apparatus and the television receiver using the same are provided with a histogram generating circuit (comparing circuit and counter), an edge detecting circuit, and a time filter. By using the letterbox video signal without the identification signal of the aspect ratio, the correct image top position,
When the image lower position and the subtitle lower position can be detected, and the aspect conversion, the vertical position shift, and the subtitle shift processing are automatically performed, the practical effect is large.

The aspect ratio automatic discrimination device according to the present invention uses a combination of a comparison circuit and a counter or a combination of an APL detection circuit and a comparison circuit to determine the darkness of a video signal in one field period. It is possible to prevent erroneous detection of the upper position of the image and the lower position of the image of the letterbox signal, and the practical effect is large.

Further, the automatic aspect ratio discrimination device according to the present invention uses a verification circuit for specifying the existence range of the upper portion of the image and the lower portion of the image of the letterbox video signal, thereby detecting the wrong upper portion of the image and the lower portion of the image. Detection can be prevented, and the practical effect is great.

The aspect ratio automatic discrimination device according to the present invention performs the case where the darkness of the video signal is determined for the entire one-field video signal and the case where the darkness determination is performed only for a specific period of the one-field video signal. By using the external signal, the accurate upper image position and lower image position of the letterbox video signal can be continuously detected, and the practical effect is large.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic aspect ratio identification device according to a first embodiment of the present invention;

FIG. 2 (a) Histogram of black (b) Histogram of image (c) Histogram of subtitle

3A is a diagram showing a specific example of 4: 3 video (b) A diagram showing a specific example of letterbox video (without subtitles) (c) A diagram showing a specific example of letterbox video (with subtitles)

FIG. 4 is a block diagram of a temporal filter according to the first embodiment of the present invention;

FIG. 5 is a timing chart of a time filter according to the first embodiment of the present invention.

FIG. 6 is a block diagram of an aspect ratio automatic identification device according to a second embodiment of the present invention;

FIG. 7 is a block diagram of an automatic aspect ratio identification device according to a third embodiment of the present invention;

FIG. 8 is a diagram showing a specific example of a video signal for explaining the operation of the third and fourth embodiments.

FIG. 9 is a block diagram of an automatic aspect ratio identification device according to a fourth embodiment of the present invention.

FIG. 10 is a block diagram of an automatic aspect ratio identification device according to a fifth embodiment of the present invention;

11A is a diagram showing a range of existence of a video start position m and a video end position n. FIG. 11B is a diagram showing prescribed values α, β, γ, and δ and boundary positions m, n, and l.
Diagram showing the relationship

12A is a diagram illustrating a specific example when a plurality of m and n are detected. FIG. 12B is a diagram illustrating a specific example when a constraint on the existence range of m is not satisfied.

FIG. 13 is a block diagram of an automatic aspect ratio identification device according to a sixth embodiment of the present invention;

FIG. 14 is a block diagram of a vertical filter according to a sixth embodiment of the present invention.

FIG. 15 is a diagram showing codes of an encoder according to a sixth embodiment of the present invention.

FIG. 16 is a timing chart of a time filter according to a sixth embodiment of the present invention.

FIG. 17 is a block diagram of an automatic aspect ratio identification device according to a seventh embodiment of the present invention;

FIG. 18 is a block diagram of a television receiver according to an eighth embodiment of the present invention.

FIG. 19A is a diagram showing a display example of a letterbox video on a display having an aspect ratio of 16: 9 according to the eighth embodiment of the present invention. FIG. 19B is a diagram showing a letterbox video of the eighth embodiment of the present invention. The figure which shows the example which expanded and displayed the image part

FIG. 20 is a block diagram of an aspect ratio identification device according to a conventional example.

21A shows a specific example of a cinema image (5: 3). FIG. 21B shows a specific example of a wide image (16: 9).

[Explanation of symbols]

1, 6, 11, 13, 15, 29 Comparison circuit 2, 3, 4, 7, 12, 28 Counter 8 Edge detection circuit 9 Time filter 10 Color signal detection circuit 14 APL detection circuit 16 Verification circuit 17 Remote controller 18 Microcomputer 19, 21, 22, 23, 25, 32, 33, 35 Flip-flop 20, 39 Match detection circuit 24, 37 AND circuit 27 Enable / disable control circuit 30, 34 Selector 31 Encoder 36 NOR circuit 38 Decoder 41 Reception channel selection unit 42 Signal Processing unit 43 A / D conversion unit 44 YC processing unit 45 Self-aspect unit 47 Subtitle processing unit 48, 49 Memory 50 Synchronization separation unit 51 Noise reducer 55 Display unit 56 Bus

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/46

Claims (22)

(57) [Claims] 1. A histogram generating means for detecting a luminance signal level of a first predetermined period unit of an input video signal and generating a histogram showing a distribution of frequency of occurrence of each luminance level,
Comparing means for classifying each luminance level occurrence frequency distribution of the output of the histogram generating means for each second predetermined period as a plurality of video types; and edge detecting means for detecting a change in the video type from the output of the comparing means. A counter that issues a timing signal for specifying a position in the input video signal of a change point to a different video type detected by the edge detection unit, and after detecting a change in the video type of the edge detection unit, A time filter for generating a position signal of a video signal when detection of the next change continues for a predetermined time, and a video type identification for identifying a video type of information contained in the input video signal from an output of the time filter. apparatus. 2. A histogram generating means for detecting a luminance signal level of a unit of a first predetermined period of an input video signal and generating a histogram indicating a frequency distribution of each luminance level,
Comparing means for classifying each luminance level occurrence frequency distribution of the output of the histogram generating means for each second predetermined period as a plurality of video types; and edge detecting means for detecting a change in the video type from the output of the comparing means. An aspect ratio automatic identification device, comprising: means for identifying the aspect ratio of the image signal portion of the input video signal from the output of the comparison means and the edge detection means. 3. A counter for issuing a timing signal for specifying a position in the input video signal of a transition point to a different video type detected by the edge detection means, and an output of the counter and the edge detection means. 3. The automatic aspect ratio identification apparatus according to claim 2, further comprising means for identifying a position of a change point of a video type in the input video signal and identifying an aspect ratio of an image portion. 4. A time filter for generating a position signal of a video signal when a change in video type is detected by an edge detecting means and a detection of the next change continues for a predetermined time. 4. The automatic aspect ratio identification apparatus according to claim 3, further comprising means for identifying a position of a change point of the image type in the input image signal and an aspect ratio of an image portion. 5. A histogram generating means for sampling a luminance signal of an input video signal and generating a histogram indicating a distribution of frequency of occurrence of each luminance level for each scanning line, and sequentially inputting the histogram generated by said histogram generating means. A comparison unit that classifies the histogram as an image type, an edge detection unit that detects a change of each scanning line of the input video signal to a different image type from an output of the comparison unit, and an edge detection unit that detects the change. A counter for issuing a timing signal for specifying the position of the transition point to the different video type in the input video signal, and a predetermined time from the detection of the video type change by the edge detection means to the detection of the next change A time filter that generates a position signal of a video signal when the time continues. Image type identification apparatus for identifying an image type of information included in the video signal. 6. A histogram generating means for sampling a luminance signal of an input video signal to generate a histogram indicating a distribution of frequency of occurrence of each luminance level for each scanning line, and sequentially inputting the histogram generated by the histogram generating means. Comparing means for classifying the histogram as an image type, edge detecting means for detecting a change of each scanning line of the input video signal to a different image type from an output of the comparing means, Means for identifying the aspect ratio of the image signal portion of the input video signal from the output of the means. 7. A counter for issuing a timing signal for specifying a position in the input video signal of a transition point to a different video type detected by the edge detection means, and an output of the counter and the edge detection means. 7. The automatic aspect ratio identification apparatus according to claim 6, further comprising means for identifying a position of a change point of the image type in the input image signal and an aspect ratio of an image portion. 8. A time filter for generating a position signal of a video signal when a change in the video type is detected by the edge detecting means and a detection of the next change continues for a predetermined time. 8. The automatic aspect ratio identification apparatus according to claim 7, further comprising: means for identifying a position of a change point of a video type in the input video signal and an aspect ratio of an image portion. 9. The aspect ratio automatic unit according to claim 2, wherein the comparison unit classifies the image type as one of black, a projected image, and a subtitle. Identification device. 10. An edge detection means, wherein a video image signal start position when the video type changes from black to the video image, a video image signal end position when the video type changes from the video image to black, and a video type from the subtitle. 10. The aspect ratio automatic identification device according to claim 9, wherein when the color changes to black, the subtitle end position is output. 11. The comparing means includes a video type of black, a projected image,
The video type identification device according to claim 1 or 5, wherein the video type is classified as one of subtitles. 12. An edge detecting means, wherein a video image signal start position when the video type changes from black to a video image, a video image signal end position when the video type changes from the video image to black, and a video type from the subtitle. 12. The video type identification device according to claim 11, wherein the video type identification device outputs each of the subtitles when the color changes to black. 13. (1) A luminance signal Y is compared with certain slice levels S and T, and a first output which becomes H level when Y <S and a second output which becomes H level when S ≦ Y ≦ T And a first comparison circuit that outputs a third output that goes high when Y> T, and (2) counts the first, second, and third outputs of the first comparison circuit First, second, and third counters; and (3) outputs N1, N2, and N3 of the first, second, and third counters.
And certain constants A, B, C, and D, and when N1> A, H
A first output to be a level, N1> B, N2 <C, N3
A second output circuit that outputs a third output that goes high when> D, a second output that goes high otherwise, and (4) a horizontal synchronization signal as a clock input and 0 to 1 each. A fourth counter for counting, and (5) receiving the first, second, and third outputs CP1, CP2, and CP3 of the second comparison circuit and the output of the fourth counter as inputs, A first output m for detecting the value of the fourth counter when the output changes from CP1 to CP2, and a second output n for detecting the value of the fourth counter when the output changes from CP2 to CP1.
And an edge detection circuit for outputting a third output 1 for detecting the value of the fourth counter when changing from CP3 to CP1, and (6) a first and second output m,
n is a first and a second input, respectively. When the input values m and n are constant for a certain period of time or more, the input values m and n are set to the first and second inputs.
Output as the second output, otherwise, regardless of the input value,
The values m 'and n' held inside the time filter are first and second values.
Video type identification device provided with a time filter for outputting as an output. 14. (1) A luminance signal Y is compared with certain slice levels S and T, and a first output which becomes H level when Y <S and a second output which becomes H level when S ≦ Y ≦ T (2) a first comparison circuit that outputs a third output that goes high when Y> T, and (2) a first comparison circuit of the first comparison circuit
First, second, and third counters for counting second and third outputs; and (3) outputs N1, N2, and N3 of the first, second, and third counters and certain constants A, B , C, and D, a first output that goes high when N1> A, and N1
> B, N2 <C, N3> D, a third comparator that outputs an H level when it is D, a second comparator that outputs a second output that is H level otherwise, and (4) a horizontal synchronization signal. A fourth counter that counts 1 from 0 with a clock input as
(5) First, second and third outputs C of the second comparison circuit
P1, CP2, CP3 and the output of the fourth counter as inputs, and a first output m for detecting the value of the fourth counter when the output of the second comparison circuit changes from CP1 to CP2.
And an edge that outputs a second output n for detecting the value of the fourth counter when changing from CP2 to CP1, and a third output 1 for detecting the value of the fourth counter when changing from CP3 to CP1. A detection circuit, and (6) when the first and second outputs m and n of the edge detection circuit are first and second inputs, respectively, and when the input values m and n are constant for a certain time or more, A time filter that outputs input values m and n as first and second outputs, and outputs values m ′ and n ′ held inside the time filter as first and second outputs, regardless of the input values otherwise. Means for identifying the aspect ratio of the image signal portion of the input video signal from the output of the time filter. 15. A color signal detection circuit which receives a color signal and outputs an H level when a color signal is detected, and outputs a second output when the output of the color signal detection circuit is at an H level. The automatic aspect ratio identification device according to claim 14. 16. An output N1 of the first counter.
And a constant RE, and a third comparator for outputting an H level when N1> RE, and (2) a fifth counter for inputting the output of the third comparator and a horizontal synchronization signal as a clock input. (3) a fourth comparator circuit which receives the output k of the fifth counter and a specified value v and outputs an H level when k> v, and (4) a first comparator of the edge detection circuit. The second output m, n and the output CP of the fourth comparison circuit
4 as first, second and third inputs, respectively, and CP4 is L
When the input values m and n are constant at a level and for a certain period of time or more, the input values m and n are output as the first and second outputs. 16. The automatic aspect ratio identification device according to claim 14, further comprising a time filter that outputs the held values m 'and n' as first and second outputs. 17. An APL detection circuit that receives a luminance signal Y as input and detects a luminance level of an entire video signal of one field, and (2) receives an output N4 and a specified value w of the APL detection circuit as inputs. (3) the first and second outputs m and n of the edge detection circuit and the output CP5 of the third comparison circuit are output as first and second signals, respectively. When CP5 is at L level and the input values m and n are constant for a certain period of time or more, the input values m and n are output as first and second outputs as second and third inputs. The aspect ratio automatic identification device according to claim 14 or 15, further comprising a time filter that outputs values m 'and n' held inside the filter as first and second outputs, irrespective of the input value except for the input values. 18. (1) First, second, and third edge detection circuits
A third output m, n, l and certain specified values α, β, γ, δ are input, and when α <m <β and γ <n <δ and l>m> n, the input values m, n, l A verification circuit that outputs the first, second, and third outputs as first, second, and third outputs, respectively, and otherwise uses the values held in the verification circuit as first, second, and third outputs, respectively, and (2) First and second outputs m ″, n ″ of the verification circuit
Are the first and second inputs, respectively. When the input values m ″ and n ″ are constant for a certain period of time or more, the input values m ″ and n ″ are output as the first and second outputs, respectively. The aspect ratio automatic identification according to claim 14 or 15, further comprising a time filter for outputting values m 'and n' held inside the time filter as first and second outputs, respectively, irrespective of an input value other than the above. apparatus. 19. (1) A luminance signal Y is compared with certain slice levels S and T, and a first output which becomes H level when Y <S, and a first output which becomes H level when S ≦ Y ≦ T. 1 having an output of H.2 and a third output that goes high when Y> T.
(2) first, second, and third counters for counting first, second, and third outputs of the first comparison circuit; and (3) the first, second, and third counters. Outputs N1, N2, N3 of the third counter
And certain constants A, B, C, and D, and when N1> A, H
A first output to be a level, N1> B, N2 <C, N3
A third output that goes high when> D, a second comparison circuit that outputs a second output that goes high when both the first and third outputs are low, and (4) the second output. , Second, third output CP1, CP2, CP3 of the second comparison circuit
, And after removing the singular point generated during the scanning period of one field, the first, second, and third output CP
A vertical filter that outputs 1 ′, CP2 ′, CP3 ′,
(5) A fourth counter which counts one from 0 by using a horizontal synchronization signal as a clock input and a vertical synchronization signal as a reset input, and (6) first, second, and third outputs CP1 of the second comparison circuit. , CP2 ', CP3' and the output of the fourth counter, and a first output for detecting the value of the fourth counter when changing from CP1 'to CP2';
An edge that outputs a second output that detects the value of the fourth counter when changing from 2 ′ to CP1 ′ and a third output that detects the value of the fourth counter when changing from CP3 ′ to CP1 ′ A detection circuit, and (7) first, second, and third outputs m, n, and l of the edge detection circuit and certain specified values α, β,
With γ and δ as inputs, m and n are uniquely determined and α <m <β
And when γ <n <δ and l>m> n, the input values m, n, l
A first, a second, and a third output, respectively, and at other times, a value held in the verification circuit as a first, a second, and a third output, respectively; and (8) the verification circuit Are the first, second, third, and fourth inputs, respectively, and the output SO of the selector described later is the first, second, third, and fourth inputs, respectively. When the values m, n, and l are constant, the input values m, n, and l are changed to the first, second, and third values, respectively.
The values m ′, n ′, and l held inside the filter are output as the first,
A time filter that outputs as second and third outputs,
(9) a third comparison circuit which receives the output N1 of the first counter and the constant RE as inputs and outputs an H level when N1> RE, and (10) inputs the output of the third comparison circuit and performs horizontal synchronization. A fifth counter having a signal as a clock input;
1) A fourth comparison circuit which receives the output k of the fifth counter and a certain specified value v and outputs an H level when k> v, and (12) outputs the output m ″ of the time filter to the first And the output of the fourth counter 4 is used as a second input, and is an H level until the output of the fourth counter 4 changes from 0 to m ″, otherwise the L level is enabled / disabled. A control circuit; and (13) a sixth counter having an output of the enable / disable control circuit as a first input, a first output CP1 ′ of the vertical filter as a second input, and a horizontal synchronization signal as a clock input. And (14) the output BN of the sixth counter as a first input, a constant Q
A second input and outputs an H level when BN> Q. (15) An output of the fourth and sixth comparison circuits is a first and a second input and a control signal, respectively. zo
n as a select input and an output SO as a fourth input of the time filter. A selector for identifying an aspect ratio of an image signal portion of the input video signal from an output of the time filter. . 20. (1) A luminance signal Y is compared with certain slice levels S and T, and a first output which becomes H level when Y <S and a second output which becomes H level when S ≦ Y ≦ T And a third output having a third output that goes high when Y> T
(2) first, second, and third counters for counting first, second, and third outputs of the first comparison circuit; and (3) the first, second, and third counters. The outputs N1, N2, N3 of the third counter are compared with certain constants A, B, C, D,
A first output that goes high when N1> A, and N1>
B, a third output that goes high when N2 <C, N3> D, and a high output when both the first and third outputs are low.
A second comparison circuit that outputs a second output that is a level,
(4) First, second and third outputs C of the second comparison circuit
P1, CP2, and CP3 are input, and after removing the singular point generated during the scanning period of one field,
A vertical filter that outputs second and third outputs CP1 ′, CP2 ′, and CP3 ′; and (5) a fourth counter that receives a horizontal synchronization signal as a clock input, receives a vertical synchronization signal as a reset input, and counts from 0 to 1 each. (6) First, second, and third outputs CP1 ', CP2', and CP3 'of the second comparison circuit and the output of the fourth counter are input, and CP1' to C
A first output for detecting the value of the fourth counter when changing to P2 ', and a fourth output for detecting the value from CP2' to CP1 '.
A second output for detecting the value of the counter, an edge detection circuit for outputting a third output for detecting the value of the fourth counter when changing from CP3 'to CP1', and (7) the edge detection circuit. , The first, second, and third outputs m, n, and l and certain specified values α, β, γ, and δ, and m and n are uniquely determined, and α <m <β and γ <n < When δ and l>m> n, input values m, n, and l are first, second, and third outputs, respectively.
At other times, a verification circuit that uses the values held in the previous verification circuit as first, second, and third outputs, respectively, and (8) first, second, and third outputs of the verification circuit. And the output SO of the selector described later as the first, second, third, and fourth inputs, respectively. When SO is at the L level and the input values m, n, and l are constant for a certain period of time or more, The input values m, n, and l are output as first, second, and third outputs, respectively. Otherwise, the values m ′, n ′,
a time filter that outputs 1 as first, second, and third outputs, and (9) a third comparison that receives an output N1 of the first counter and a constant E and outputs an H level when N1> E. (10) a fifth counter which receives the output of the third comparison circuit as an input and receives a horizontal synchronization signal as a clock input;
1) a fourth comparison circuit which receives an output k of the fifth counter and a specified value v and outputs an H level when k> v, and (12) an output m ″ and n ″ of the time filter. A first input, a second input, an output of the fourth counter 4 as a third input, a certain constant P as a fifth input, and a fourth counter 4
And (13) the enable / disable control circuit which is at H level until the output of m changes from m 'to m' + P and n'-P to n ', and otherwise at L level. A sixth counter having an output of the circuit as a first input, a first output CP1 'of the vertical filter as a second input, and a horizontal synchronization signal as a clock input; and (14) an output BN of the sixth counter. A first input, a certain constant Q as a second input, and an output of H level when BN> Q. (15) The outputs of the fourth and sixth comparison circuits are The first and second inputs and the control signal zon are provided as select inputs, and the output SO identifies the aspect ratio of the image signal portion of the input video signal from the output of the selector as the fourth input of the time filter. hand Automatic aspect ratio discrimination apparatus having and. 21. A receiving means for inputting an input video signal,
A first signal processing unit for performing a first signal processing for demodulating a luminance signal, a chrominance signal, and the like of a video signal input by the receiving unit, and an image quality improvement for the signal processed by the first signal processing unit A second signal processing means for performing a second signal processing for performing a secondary signal processing, and a drive signal for displaying the video signal information is output by using a signal processed by the second signal processing means. And a display unit driven by a drive signal output by the drive unit and displaying the video signal information, wherein the first signal processing unit has a first predetermined period of the digital video signal. A histogram generating means for detecting a luminance signal level for each unit and generating a histogram indicating a distribution of frequency of occurrence of each luminance level; Comparing means for classifying each luminance level occurrence frequency distribution of force as a plurality of image types; edge detecting means for detecting a change in the image type from the output of the comparing means; and Means for identifying an aspect ratio of an image signal portion of an input video signal. 22. A receiving means for inputting an input analog video signal, a first signal processing means for converting the analog video signal input by the receiving means into a digital video signal and performing a first signal processing; A second signal processing means for performing a second signal processing and a digital / analog conversion of the signal processed by the first signal processing means, and a signal which has been analog-converted by the second signal processing means. The first signal processing means, comprising: drive means for outputting a drive signal for displaying the video signal information; and display means driven by the drive signal output by the drive means for displaying the video signal information. Detecting a luminance signal level of the digital video signal for each first predetermined period unit, and generating a histogram indicating a frequency distribution of each luminance level. Histogram generating means for generating, a comparing means for classifying each luminance level occurrence frequency distribution of the output of the histogram generating means for each second predetermined period as a plurality of video types, and a change of the video type based on an output of the comparing means. A television receiver comprising: an edge detecting means for detecting an image signal; and a means for identifying an aspect ratio of an image signal portion of the input video signal from outputs of the comparing means and the edge detecting means.