JP2006295618A - Signal processor circuit, integrated circuit, program, signal processing method, imaging apparatus, and memory medium reproducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel and improved signal processor circuit, an integrated circuit, a program, a signal processing method, an imaging apparatus, and a memory medium reproducer which processes the picture into a picture with colors more nearer to primary colors and vivid like a film in real time. <P>SOLUTION: The signal processor circuit comprises a plurality of signal lines 210, a difference calculator 220 for calculating the difference between the signal levels of a specific signal line and other signal line, a corresponding signal output unit 230 for outputting a signal corresponding to the calculated difference, and a level limiter 240 for limiting the signal level on the specific signal line according to the corresponding signal. This expands the difference between the signal levels and changes the picture to a picture with bright colors on the whole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a signal processing circuit, an integrated circuit device, a program, a signal processing method, an imaging device, and a storage medium playback device that relatively process signal levels flowing through a plurality of signal lines.

  2. Description of the Related Art Conventionally, in an apparatus that handles video, such as a video camera, arithmetic processing has been performed so as to maintain the luminance of each of the three primary colors of red, green, and blue, and the video as it is seen with the naked eye has been expressed. Therefore, in such an apparatus, color correction that is substantially away from an image as seen with the naked eye is not performed, and even if color correction is performed, an unnatural change is not felt with the naked eye.

  As described above, in the conventional video reproduction device, the video is reproduced so that the color and the luminance are faithfully reproduced based on the broadcast standard and the video recording standard. Therefore, the conventional video reproduction device that faithfully reproduces the original video cannot express vivid colors more than the naked eye can see.

  Conventionally, the brightness of the video screen divided into multiple parts is weighted, and the lens aperture is adjusted to keep the average level constant. Although there is a technique (for example, Patent Document 1) that adjusts exposure by paying attention to the luminance level of a pixel having information, this technique is also a technique that performs only simple adjustment such as adjustment of overall brightness. , It does not express vivid colors.

  Further, in image formation using a film, for example, red can be changed to pure red and blue can be changed to pure blue because of its physical properties. Therefore, a photograph using film can express a vivid color overall. In the conventional video reproduction device, in order to realize such a vivid hue, a time-consuming process such as partial editing of an image once stored is necessary.

JP-A-8-237543

  The present invention has been made in view of the above-described problems of conventional video reproduction apparatuses, and the object of the present invention is to process video in real time in a color closer to the primary color and vivid like a film. A new and improved signal processing circuit, integrated circuit device, program, signal processing method, imaging device, and storage medium reproducing device are provided.

  The present invention maintains a signal level as it is for a signal with a high signal level among a plurality of signals (for example, three primary colors) forming an image, and changes the signal level for a signal with a low signal level. By lowering it, the color of the high signal level is expressed more clearly, and the image is corrected to a vivid color as a whole.

  In order to solve the above problems, according to an aspect of the present invention, a plurality of signal lines; a difference for calculating a difference in signal level between a specific signal line and another signal line among the plurality of signal lines; A calculation unit; a corresponding signal output unit that outputs a corresponding signal corresponding to the calculated difference; and a level limiting unit that limits a signal level of the specific signal line by the corresponding signal. A signal processing circuit is provided. The signal lines may be signal lines that transmit the three primary color signals of the video. Here, when the number of signal lines is n, n × (n−1) of the difference calculation units, corresponding signal output units, and level limiting units may be provided.

  With this configuration, it becomes possible to automatically limit the signal level according to the difference in signal level of each signal line. A high signal level is expressed as a high level, and a low signal level is expressed as a low level. The overall color can be corrected to vivid colors.

  The difference calculation unit subtracts the signal level of the other signal line from the signal level of the specific signal line, and the corresponding signal output unit is unrestricted (does not limit) when the subtraction result is positive. The signal may be output, and the level limiting unit may maintain the signal level of the specific signal line according to the signal without limitation.

  With this configuration, when the signal level of the specific signal line is higher than the signal level of the other signal line according to the difference between the signal level of the specific signal line and the signal level of the other signal line (the subtraction result is positive) In addition, the signal level of a specific signal line can be maintained.

  The corresponding signal output unit outputs a limited signal when the subtraction result is negative, and the level limiting unit may reduce the signal level of the specific signal line according to the limited signal. good.

  With this configuration, when the signal level of the specific signal line is higher than the signal level of the other signal line according to the difference between the signal level of the specific signal line and the signal level of the other signal line, the specific signal line The signal level can be limited only when the signal level of the specific signal line is maintained and the signal level of the other signal line is lower (the subtraction result is negative). By lowering the low signal level in this way, it is possible to obtain the same effect as a relatively high high signal level.

  When the subtraction result is negative, the corresponding signal output unit may output a signal whose limit amount increases as the difference of the difference calculation unit increases.

  With this configuration, when the signal level of a specific signal line is lower than the signal level of another signal line according to the difference between the signal level of the specific signal line and the signal level of the other signal line, the difference is large. The larger the value, the lower the signal level of a specific signal line (monotonic decrease), and it becomes possible to process a clearer image.

  The corresponding signal output unit can output a corresponding signal corresponding to the difference with reference to a lookup table. Further, the corresponding signal may be derived by a function using the difference as an argument.

  In the lookup table (hereinafter referred to as LUT), a value corresponding to one-to-one is written in the difference, and the corresponding signal is output with reference to the value. The LUT may be provided in the corresponding signal output unit or may be referred to from an external device. The LUT is usually formed by storing a numerical value in advance at an address corresponding to the difference of a storage medium such as a memory. When the resolution of the LUT is low, a value between them is created by linear interpolation or linear approximation.

  A low-pass filter may be further provided between the specific signal line and the difference calculation unit.

  A sudden change in the signal level due to noise or the like further has an undesirable effect on the main signal line via the signal processing circuit. With the configuration of such a low-pass filter (hereinafter referred to as LPF), it is possible to prevent the signal line from being affected by a sudden change in signal level.

  In order to solve the above problems, according to another aspect of the present invention, a plurality of signal lines; a difference calculation unit that calculates a difference in signal level between a specific signal line and another signal line; An integrated circuit device comprising: a corresponding signal output unit that outputs a corresponding signal corresponding to the difference; and a level limiting unit that limits a signal level of the specific signal line by the corresponding signal. Is provided.

  Such an integrated circuit device is a device in which the signal processing circuit is integrated. Therefore, as with the signal processing circuit, it is possible to automatically limit the signal level according to the difference in signal level of each signal line, with the higher signal level being higher and the lower signal level being expressed lower. Can be corrected to vivid colors as a whole.

  The invention shown in the dependent claims relating to the signal processing circuit can also be applied to the integrated circuit device.

  In order to solve the above problems, according to another aspect of the present invention, a step of calculating a difference between a specific signal level and another signal level is output to a computer; and a value corresponding to the calculated difference is output. And a step of restricting the specific signal level by the corresponding value. A program is provided.

  The signal processing circuit can be realized by an analog or digital circuit, but can also operate as a computer program. Here, a plurality of signal levels that form an image input to the computer are processed by a program, and the signal levels are processed. This program maintains the same signal level for signals with a high signal level, and lowers the signal level for signals with a low signal level. Expresses clearly and corrects the entire image to vivid colors.

  In order to solve the above problems, according to another aspect of the present invention, a computer calculates a difference between a specific signal level and another signal level; and outputs a value corresponding to the calculated difference. And a step of restricting the specific signal level by the corresponding value. A signal processing method is provided.

  Similar to the above program, a signal processing method for performing signal processing on a computer can also be realized. Again, the high signal level color is made clearer by maintaining the same signal level for signals with high signal levels and lowering the signal level for signals with low signal levels. The image is corrected to vivid colors as a whole.

  Further, the processing shown in the dependent claims relating to the signal processing circuit can be applied to the program and the signal processing method.

  In order to solve the above problems, according to another aspect of the present invention, a signal line for transmitting three primary color signals of a captured image, respectively; a difference in signal level between a specific signal line and another signal line is obtained. A difference calculating unit for calculating; a corresponding signal output unit for outputting a corresponding signal corresponding to the calculated difference; a level limiting unit for limiting a signal level of the specific signal line by the corresponding signal; And an image storage unit for storing an image signal expressed by the signal level.

  With this configuration, when a video is captured by the imaging apparatus, the video can be processed clearly in real time, and the stored vivid video (including audio) can be viewed.

  Further, the invention shown in the dependent claims relating to the signal processing circuit can also be applied to the imaging apparatus.

  In order to solve the above problems, according to another aspect of the present invention, a video reading unit that reads a video signal from a storage medium; a signal line that transmits three primary color signals of the read video; and a specific signal line A difference calculation unit that calculates a difference in signal level between the signal and another signal line; a corresponding signal output unit that outputs a corresponding signal corresponding to the calculated difference; and a signal of the specific signal line by the corresponding signal There is provided a storage medium playback device comprising: a level limiting unit that limits a level; and a video display unit that displays a video represented by the limited signal level.

  With such a configuration, it is possible to reproduce a conventional storage medium and at the same time vividly process the video so that a vivid video can be viewed.

  The invention shown in the dependent claims relating to the signal processing circuit can also be applied to the storage medium reproducing apparatus.

  As described above, according to the present invention, an image can be corrected in real time to a vivid color like a film closer to the primary color. Therefore, an image taken by a so-called CCD, CMOS, or the like such as an electronic photograph has a vivid color like a film photograph.

  In addition, depending on the degree of processing, it is possible to express beyond the film photograph, and it can be used as a special effect. In addition, images that have been formed with a whitish color when the iris (aperture for adjusting the amount of light) is opened too much at the time of shooting have a slight difference between the signal levels in the images. If so, the difference is emphasized, and the image after processing becomes clear.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  In image formation using photographic technology such as film, red changes to pure red and blue changes to pure blue due to its physical properties. Accordingly, it is possible to express a vivid color overall. However, the conventional video playback device that faithfully reproduces the video at the time of shooting has been unable to express vivid colors more than the naked eye can see.

  In the embodiment of the present invention, a configuration is described in which an operation corresponding to the interimage effect is performed on each signal forming an image, and the signal level is increased or decreased from the relative signal level relationship between the signal lines.

  Here, among a plurality of signals forming an image (for example, three primary colors), the signal level is maintained as it is for the signal level is high, and the signal level is decreased for the signal with a low signal level. As a result, the color of the high signal level is expressed more clearly, and the image is corrected to a color close to the vivid primary color as a whole.

(First embodiment: signal processing circuit)
FIG. 1 is a circuit diagram showing a signal processing circuit according to the first embodiment. The signal processing circuit 100 includes a signal line 110, a difference calculation unit 120, a corresponding signal output unit 130, and a level limiting unit 140.

  The signal lines 110 (110a, 110b) transmit color signals such as black and white, for example. In FIG. 1, the color signal is input from “Black In” or “White In”, and is output to “Black Out” or “White Out” via the signal lines 110a and 110b, respectively. The signal line 110 connected directly from the input to the output is called a main line.

  The difference calculation unit 120 (120a, 120b) can be realized by a subtraction circuit or the like, and calculates a difference in signal level between a specific signal line and another signal line. For example, paying attention to “Black”, the difference calculation unit 120a detects the signal level from the specific “Black” signal line 110a and the other “White” signal line 110b, and from the “Black” signal level to “White”. "Is subtracted, and the result is output to the corresponding signal output unit 130a for" Black ". Accordingly, when the “Black” signal level is higher than the “White” signal level, a positive value is output, and vice versa.

  In addition, the difference calculation unit 120b regarding “White” subtracts the signal level of “Black” from the signal level of “White” and outputs the result to the corresponding signal output unit 130b regarding “White”.

  The corresponding signal output unit 130 (130a, 130b) is connected to the difference calculation unit 120 (120a, 120b) and outputs a corresponding signal corresponding to the difference calculated by the difference calculation unit 120. For example, the corresponding signal output unit 130a related to “Black” calculates the corresponding signal based on a value obtained by subtracting the signal level of “White” from the signal level of “Black”. Basically, when the difference shows a positive value, the corresponding signal is selected so as to emphasize the specific color (for example, “Black”) as the difference is larger, and when the difference shows a negative value, the difference is larger. The corresponding signal is selected so that the specific color is not noticeable.

  The level limiting unit 140 (140a, 140b) can be realized by a multiplication circuit or the like, and limits or amplifies the signal level of a specific signal line by the corresponding signal from the corresponding signal output unit 130. For example, focusing on “Black”, a corresponding signal is received from the corresponding signal output unit 130a related to “Black” and multiplied by the signal level of “Black”. Assuming that the corresponding signal is a value centered on 1, when the corresponding signal is 1 or less, the signal level of the “Black” decreases, and when the corresponding signal is 1 or more, the signal level is amplified. The

  Here, n × (n−1) difference calculation units 120, corresponding signal output units 130, and level limiting units 140 are provided when the number of signal lines 110 is n. Therefore, in the present embodiment, two each of the above-described parts are provided.

  As described above, according to the present embodiment, when a specific signal is compared with other signals, the specific signal is emphasized when the difference is large, and the signal is limited so that it is less noticeable when the difference is small. The When the signal processed in this way is judged as an overall image, each part of the image changes to a vivid color like a film that is closer to the primary color.

(Second Embodiment: Signal Processing Circuit)
FIG. 2 is a circuit diagram showing a signal processing circuit in the second embodiment. The signal processing circuit 200 includes a signal line 210, a low-pass filter 212, a difference calculation unit 220, a corresponding signal output unit 230, and a level limiting unit 240.

  The signal lines 210 (210a, 210b, 210c) transmit color signals such as red, green, and blue, for example. In the main line of FIG. 2, the color signals are input from “Red In”, “Green In”, and “Blue In”, and “Red Out” and “Green Out” are transmitted through the signal lines 210a, 210b, and 210c, respectively. , “Blue Out”.

  The low-pass filter 212 (212a, 212b, 212c) is provided between the signal line 210 and the difference calculation unit 220, and prevents the signal line from being affected by a sudden change in signal level due to noise or the like.

  The low-pass filter 212 can be realized by an RC circuit or a filter using an amplifier if the signal processing circuit 200 is an analog circuit, and can be realized by using, for example, an FIR (Finite Impulse Response) filter if it is a digital circuit. it can. An example of a low pass filter using an FIR filter is shown below.

FIG. 3 is a circuit diagram showing the FIR filter. The FIR filter ( _{1, 2} , ₁ ) is expressed by, for example, an equation Y _k = x _k + 2 × x _k−1 + x _k−2 . Here, the output Y _k is determined by the current input (x _k ), the input (x _k−1 ) before one sampling, and the input (x _k−2 ) before two samplings.

  Referring to FIG. 3, the input before one sampling and the input before one sampling are accumulated through a shift register such as a flip-flop (FF) 310 connected to a specific signal line (for example, “Red”). Has been. The above three inputs including the input from the signal line are output to the multiplier 320 and multiplied by constants 1, 2, and 1, respectively. Finally, the result obtained by adding the multiplication results by the adder 330 is divided by 4, for example, and transmitted to the difference calculation unit 220.

  The difference calculation unit 220 (220a, 220b, 220c, 220d, 220e, 220f) is realized by a subtraction circuit or the like, and calculates a difference in signal level between a specific signal line and another signal line. For example, focusing on “Red”, the difference calculation unit 220a detects a signal level from a specific “Red” signal line 210a and another “Green” signal line 210b, and determines “Green” from the “Red” signal level. "Is subtracted, and the result is output to the corresponding signal output unit 230a for" Red ".

  Similarly, the difference calculation unit 220b detects the signal level from the specific “Red” signal line 210a and the other “Blue” signal line 210c, and from the “Red” signal level to the “Blue” signal level. And the result is output to the corresponding signal output unit 230b regarding “Red”. The difference calculation units 220c, 220d, 220e, and 220f regarding the other “Green” and “Blue” also have the same function.

  The corresponding signal output unit 230 (230a, 230b, 230c, 230d, 230e, 230f) is connected to the difference calculation unit 220 (220a, 220b, 220c, 220d, 220e, 220f) and calculated by the difference calculation unit 220. A corresponding signal corresponding to the difference is output. For example, the corresponding signal output unit 230a related to “Red” calculates a corresponding signal based on a value obtained by subtracting the signal level of “Green” from the signal level of “Red”, and the corresponding signal output unit 230b of “Red” The corresponding signal is calculated based on the value obtained by subtracting the signal level of “Blue” from the signal level.

  In this embodiment, an LUT is used for calculating the corresponding signal.

  FIG. 4 is an explanatory diagram for explaining the LUT referred to by the corresponding signal output unit 230. The LUT is provided for each corresponding signal output unit 230, and can be represented by a graph with the horizontal axis 410 representing the difference calculated by the difference calculating unit 220 and the vertical axis 420 representing the corresponding signal. Specifically, it is formed by storing the corresponding numerical value in advance at about 20 addresses corresponding to the above differences of the storage medium such as a memory, and the part where the address does not exist is created by linear interpolation or linear approximation. Is done. Such an LUT is also called a gain table because it creates a signal level gain in accordance with the input.

  According to the LUT, when the difference shows a positive value, 1.0 is selected as the corresponding signal regardless of the magnitude of the difference (430). When the difference shows a negative value, the corresponding signal decreases as the difference increases (the absolute value of the difference increases) (440). The curve when the difference is negative can be determined for each corresponding signal output unit 230 according to the characteristics of the two signal levels that are the basis of the difference.

  By the way, although the concept of white balance is not necessary in the film, white balance is necessary in the present embodiment that handles video signals. Therefore, in any LUT as shown in FIG. 4, when there is no difference in the input difference (difference 0), for example, when the signal levels of the three primary colors are equal, all the corresponding signals are set to 1.0. In this way, white balance is maintained.

  FIG. 5 is an explanatory diagram for explaining another example of the LUT. Here, unlike the LUT described in FIG. 4, when the difference shows a positive value, the larger the difference (the larger the absolute value of the difference), the larger the corresponding signal (450), and the difference becomes negative. If a value is indicated, 1.0 is selected as the corresponding signal regardless of the magnitude of the difference (460). The configuration of FIG. 5 has a rough gradation expression as compared with FIG. Furthermore, an LUT combining FIG. 4 and FIG. 5 can also be implemented.

  The level limiting unit 240 (240a, 240b, 240c, 240d, 240e, 240f) can be realized by a multiplication circuit or the like, and limits or amplifies the signal level of a specific signal line by the corresponding signal from the corresponding signal output unit 230. . For example, focusing on “Red”, the level limiting unit 240a receives the corresponding signal from the corresponding signal output unit 230a regarding “Red”, and multiplies it with the signal level on the signal line 210a of “Red”. Further, the level limiting unit 240b receives the corresponding signal from the corresponding signal output unit 230b at the subsequent stage of the level limiting unit 240a, and multiplies it with the signal level on the “Red” signal line after the level limiting unit 240a limits. Yes.

  Hereinafter, the above configuration will be specifically described based on the relationship of signal levels.

FIG. 6A is an explanatory diagram showing signal levels of the three primary colors at arbitrary pixels of the video. Three colors “Red”, “Green”, and “Blue” are input to the signal processing circuit 200 without much difference between the signal levels, and are represented by R _in , G _in , and B _{in in} FIG. 6A. The In this pixel, the inputs R _in , G _in , and B _in have a relationship of | R _in |> | G _in |> | B _in |.

First, focusing on “Red”, the output of the difference calculation unit 220a becomes a positive value at R _in −G _in , and the output of the difference calculation unit 220b also becomes a positive value at R _in −B _in . Therefore, the corresponding signal output units 230a and 230b output 1.0 as the corresponding signal with reference to the LUT shown in FIG. The level limiting units 240a and 240b limit the “Red” signal by the corresponding signal 1.0, but do not limit the multiplication by 1.0. That is, the “Red” signal is the input signal. Maintains the same level as the level.

Next, paying attention to “Green”, the output of the difference calculation unit 220c is a negative value of G _in −R _in , and the corresponding signal output unit 230c refers to the LUT shown in FIG. Output a signal. Further, the output of the difference calculation unit 220d becomes a positive value at G _in −B _in . Accordingly, the corresponding signal output unit 230d outputs a corresponding signal of 1.0. Subsequently, the level limiting units 240c and 240d limit the “Green” signal. First, the level limiting unit 240c multiplies the level of the “Green” signal by 0.8 using the corresponding signal 0.8. Since the corresponding signal 1.0 is input to the level limiting unit 240d, the signal level multiplied by 0.8 is maintained. Therefore, the final “Green” signal level is 0.8 times that at the time of input.

Finally, focusing on “Blue”, the output of the difference calculation unit 220e is a negative value at B _in −R _in and the output of the difference calculation unit 220f is also a negative value at B _in −G _in . Here, the absolute values of B _in −R _in and B _in −G _in are different. With reference to the LUT shown in FIG. 4, the corresponding signal output unit 230e outputs a corresponding signal of 0.2, and the corresponding signal output unit 230f outputs a corresponding signal of 0.8. Therefore, the signal level of “Blue” is limited to 0.2 × 0.8 = 0.16 times by the level limiting units 240e and 240f.

  FIG. 6B is an explanatory diagram showing the signal level after passing through the signal processing circuit 200. In FIG. 6A, there is not much difference between the three primary colors, but in FIG. 6B, only the color signal (Red) having the maximum signal level is maintained, and the other color signals (Green, Blue) are reduced. Further, the signal level is narrowed as the signal level is low, and the hue is prioritized as the signal level is high.

  For example, even when the sunset is imaged at dusk when the light is low, the signal level other than “Red” of the sunset is lowered, and the saturation of “Red” is increased as described in the above embodiment.

  Also, for example, even when a dull blue sky is imaged when the weather is somewhat bad, the blue color can be emphasized.

FIG. 7 is a time chart showing signal waveforms in the respective color signals when the inputs R _in , G _in , and B _{in in} an arbitrary pixel group have a relationship of | R _in | <| G _in | <| B _in |. It is. Here, the input is represented by Red In, Green In, and Blue In, and the output after passing through the signal processing circuit 200 is represented by Red Out, Green Out, and Blue Out.

In the signal processing circuit 200, calculation is performed based on the relationship of | R _in | <| G _in | <| B _in |, and only the color signal (Blue) having the maximum signal level is shown in FIG. This is maintained, and the signal levels of the other color signals (Red, Green) are reduced. Even when comparing such Red and Green, it is understood that the reduction rate of Red is larger than the reduction rate of Green. The signal processed in this way will be described below as an image.

  8A and 8B are explanatory diagrams showing effects when the signal processing circuit 200 is applied to an arbitrary video. Here, FIG. 8A shows the captured video itself, and FIG. 8B shows the video after passing through the signal processing circuit 200. As can be understood with reference to such a diagram, the overall dull blue sky shown in FIG. 8A also has a lower signal level other than “Blue” in the video, and the saturation of “Blue” increases. It can be changed to a bright blue sky as shown in 8B.

  As described above, the signal processing circuit 200 automatically restricts the signal level according to the signal level difference between the signal lines. If the difference is large, the specific signal is emphasized. The signal is limited so that it does not stand out. When the signal processed in this way is judged as an overall image, each part of the image is processed into a vivid color like a film, which is closer to the primary color.

Further, when the relationship | R _in | = | G _in | = | B _in | holds (when the pixel is achromatic), the corresponding signal output unit 230 (230a, 230b, 230c, 230d, 230e, 230f) The outputs are all 1.0, and the “Red”, “Green”, and “Blue” signals are not limited. That is, the input signal levels of the “Red”, “Green”, and “Blue” signals are maintained.

  The number of difference calculation units 220, corresponding signal output units 230, and level limiting units 240 of this embodiment is 6 as 3 × (3-1) because there are three signal lines 210. Further, since one low-pass filter 212 is provided for each signal line 210, the number is three.

  With this configuration, even in this embodiment, it is possible to form an image similar to film “image creation” resulting from filming and developing characteristics of a film camera. That is, color reproducibility similar to that of a film camera can be obtained in a video camera.

(Third Embodiment: Integrated Circuit Device)

  In addition, an integrated circuit device that includes the signal line 210, the low-pass filter 212, the difference calculation unit 220, the corresponding signal output unit 230, and the level limiting unit 240 in the signal processing circuit 200 is also provided.

  Similar to the signal processing circuit 200, such an integrated circuit device can automatically limit the signal level according to the difference in the signal level of each signal line 210. The higher signal level is higher and the lower signal level is higher. The level is expressed lower, and the image can be corrected to a vivid color as a whole.

(Fourth embodiment: program, signal processing method)
The signal processing circuit 200 described above can also operate as a program using a computer.

  FIG. 9 is a flowchart showing a flow of performing signal processing by a program using a computer. According to this flowchart, the computer first extracts a specific signal from a plurality of signals in the video, and calculates a difference between the signal level of the specific signal and another signal level (S500).

  Subsequently, the LUT stored in the computer is referred to (S510), and a value corresponding to the calculated difference is derived (S520). The computer limits the specific signal level according to the corresponding value thus derived (S530). Such a flow is repeated by the number of signals or is executed in parallel.

  In this way, a plurality of signal levels forming an image input to the computer are processed by the program, and the signal levels are processed. This program maintains the same signal level for signals with a high signal level and lowers the signal level for signals with a high signal level. Is more clearly displayed, and the image is corrected to a vivid color as a whole.

  Also provided are a storage medium storing the program and a signal processing method in which a computer executes the program and performs signal processing.

(Fifth embodiment: imaging device)
The signal processing circuit 200 described above can also be applied to an imaging apparatus that captures a video and stores the captured video in a storage medium.

  FIG. 10 is a block diagram illustrating a schematic configuration of an imaging apparatus according to the fifth embodiment. The imaging apparatus 600 includes an imaging unit 610, a conversion unit 612, a white balance / shading unit 614, a linear matrix unit 616, a signal processing circuit 200, a knee circuit 618, a gamma circuit 620, and white / black. A clip unit 622 and a video storage unit 624 are included.

  Since the signal processing circuit 200 already described as a component in the second embodiment has substantially the same function, redundant description will be omitted, and here, components having different configurations will be described.

  The image pickup unit 610 separates an image of the outside world into color signals of three primary colors using a prism, and then converts them into signals of the three primary colors using an image pickup device such as a CCD or CMOS. In this embodiment, video signal processing by the imaging unit 610 is performed, but such video may be acquired from another storage medium or a communication network such as the Internet.

  The conversion unit 612 performs DC clamping and gain adjustment for each signal line on the signal from the imaging unit 610, and further performs analog / digital (A / D) conversion for subsequent digital processing.

  The white balance / shading unit 614 performs gain adjustment for changing white to white, that is, white balance for each signal line for the digital signal converted by the conversion unit 612, and performs shading of the optical system. . Here, correction of the aperture effect or the like of the CCD device may be further performed.

  The linear matrix unit 616 corrects the leakage of color signals after being separated into the three primary colors of the optical system in the above configuration by matrix calculation in the linear region.

  The knee circuit 618 compresses the high luminance area using the characteristics of the knee curve in order to improve the reproducibility of the high luminance area in the final video display.

  FIG. 11 is an explanatory diagram showing an example of the knee curve. In such a knee curve (solid line), the reproducibility of the video in the high luminance region is ensured by performing conversion that limits the signal level in the high luminance region.

  The gamma circuit 620 uses the gamma characteristic to prevent the image of the image display unit such as a cathode ray tube monitor from changing due to the inverse gamma characteristic, thereby realizing a final linear display of the image.

  FIG. 12 is an explanatory diagram showing an example of a gamma curve having the above gamma characteristics. In such a gamma curve (solid line), conversion is performed to nonlinearly amplify the signal level in an arbitrary region.

  The white / black clip unit 622 cuts the signal level in an area that cannot be processed or ignored in the subsequent circuit. The above region is a signal that is greater than or equal to the maximum signal level that can be handled or less than the minimum value, and the cut can be realized by, for example, a band pass filter (BPF).

  The video storage unit 624 stores a video represented by the signal restricted by the level restriction unit 240 in a storage medium. Such a storage medium may be constituted by a memory (RAM, EEPROM), HDD, magneto-optical disk, storage, or the like.

  An output unit (not shown) that outputs a video signal to the outside of the imaging apparatus 600 may be provided instead of or in parallel with the video storage unit 624. The output unit converts the color signal formed by the white / black clip unit 622 into a desired signal format, and outputs the returned signal through the output terminal.

  With this configuration, when an image is captured by the imaging apparatus 600, the image can be processed clearly, and the stored vivid image can be viewed.

(Sixth embodiment: storage medium playback apparatus)
The signal processing circuit 200 described above can also be applied to a storage medium playback device that plays back a storage medium as video.

  FIG. 13 is a block diagram showing a schematic configuration of a storage medium reproducing device according to the sixth embodiment. The storage medium playback device 650 includes a video reading unit 660, a signal line 210, a low pass filter 212, a difference calculation unit 220, a corresponding signal output unit 230, a level limiting unit 240, and a video display unit 670. Consists of.

  Since the signal line 210, the low-pass filter 212, the difference calculation unit 220, the corresponding signal output unit 230, and the level limiting unit 240, which have already been described as constituent elements in the second embodiment, have substantially the same functions, they overlap. The description is omitted, and here, the video reading unit 660 and the video display unit 670 having different configurations will be mainly described.

  The video reading unit 660 reads a video signal from a storage medium such as a memory (RAM, EEPROM), HDD, magneto-optical disk, or storage. Further, such video may be acquired from a communication network such as the Internet.

  The video display unit 670 combines the signals limited by the level limiting unit 240 in units of pixels, and displays the video expressed as a whole on a display or the like.

  With such a configuration, it is possible to reproduce a conventional storage medium and at the same time vividly process the video so that a vivid video can be viewed.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are of course within the technical scope of the present invention. Understood.

  For example, a plurality of level limiting units of the second embodiment are provided for each signal line. However, the level limiting unit is not limited to such a case. It may be input to one level limiting unit.

  That is, the corresponding signals 0.2 and 0.8 of the “Blue” corresponding signal output units 230e and 230f in the second embodiment are preliminarily multiplied, and one level limiting unit determines “ The signal level of “Blue” may be limited.

  In the above-described embodiment, the configuration in which the corresponding signal is created with reference to the LUT has been described. However, the present invention is not limited to this, and the corresponding signal may be derived by a function for the difference. In such a case, the order of the function is not limited.

  In the above-described embodiment, a single curve is exemplified as the LUT. However, the LUT is not limited to such a single curve, and a different LUT may be provided for each corresponding signal output unit.

  Note that each step in the signal processing method of the present specification does not necessarily have to be processed in time series in the order described in the flowchart, but is performed in parallel or individually (for example, parallel processing or object-based processing). Processing).

  The present invention is applicable to a signal processing circuit, an integrated circuit device, a program, a signal processing method, an imaging device, and a storage medium reproducing device that relatively process signal levels flowing through a plurality of signal lines.

It is a circuit diagram showing a signal processing circuit in a first embodiment. It is the circuit diagram which showed the signal processing circuit in 2nd Embodiment. It is the circuit diagram which showed the FIR filter. It is explanatory drawing for demonstrating LUT which a corresponding signal output part refers. It is explanatory drawing for demonstrating the other example of LUT. It is explanatory drawing which showed the signal level of 3 primary colors in the arbitrary pixels of an image | video. It is explanatory drawing which showed the signal level after passing through a signal processing circuit. It is a time chart which showed the signal waveform in each color signal. It is explanatory drawing which shows the effect at the time of applying a signal processing circuit to arbitrary videos. It is explanatory drawing which shows the effect at the time of applying a signal processing circuit to arbitrary videos. It is the flowchart which showed the flow which performs a signal processing by the program using a computer. It is the block diagram which showed the schematic structure of the imaging device in 5th Embodiment. It is explanatory drawing which showed an example of a knee curve. It is explanatory drawing which showed an example of the gamma curve which has a gamma characteristic. It is the block diagram which showed the schematic structure of the storage medium reproducing | regenerating apparatus in 6th Embodiment.

Explanation of symbols

100, 200 Signal processing circuit 110, 210 Signal line 120, 220 Difference calculation unit 130, 230 Corresponding signal output unit 140, 240 Level limiting unit 212 Low pass filter 600 Imaging device 610 Imaging unit 624 Video storage unit 650 Storage medium playback device 660 Video Reading unit 670 Video display unit

Claims (12)

Multiple signal lines;
A difference calculation unit for calculating a difference in signal level between a specific signal line and another signal line;
A corresponding signal output unit for outputting a corresponding signal corresponding to the calculated difference;
A level limiter for limiting the signal level of the specific signal line by the corresponding signal;
A signal processing circuit comprising: The difference calculation unit subtracts the signal level of another signal line from the signal level of the specific signal line,
The corresponding signal output unit outputs an unrestricted signal when the subtraction result is positive,
2. The signal processing circuit according to claim 1, wherein the level limiting unit maintains a signal level of the specific signal line in accordance with the unrestricted signal. The corresponding signal output unit outputs a limited signal when the subtraction result is negative,
The signal processing circuit according to claim 2, wherein the level limiting unit lowers the signal level of the specific signal line in accordance with the limited signal.   4. The signal processing circuit according to claim 3, wherein, when the subtraction result is negative, the corresponding signal output unit outputs a signal whose limit amount increases as the difference of the difference calculation unit increases. 5. .   The signal processing apparatus according to claim 1, wherein the corresponding signal output unit outputs a corresponding signal corresponding to the difference with reference to a lookup table.   The signal processing circuit according to claim 1, further comprising a low-pass filter between the specific signal line and the difference calculation unit.   The signal processing circuit according to claim 1, wherein the signal lines are signal lines for transmitting three primary color signals of an image. Multiple signal lines;
A difference calculation unit for calculating a difference in signal level between a specific signal line and another signal line;
A corresponding signal output unit for outputting a corresponding signal corresponding to the calculated difference;
A level limiter for limiting the signal level of the specific signal line by the corresponding signal;
An integrated circuit device comprising: Computer
Calculating a difference between a specific signal level and another signal level;
Outputting a value corresponding to the calculated difference;
Limiting the specific signal level by the corresponding value;
A program characterized by running Computer
Calculating a difference between a specific signal level and another signal level;
Outputting a value corresponding to the calculated difference;
Limiting the specific signal level by the corresponding value;
The signal processing method characterized by performing. A signal line for transmitting each of the three primary color signals of the captured image;
A difference calculation unit for calculating a difference in signal level between a specific signal line and another signal line;
A corresponding signal output unit for outputting a corresponding signal corresponding to the calculated difference;
A level limiter for limiting the signal level of the specific signal line by the corresponding signal;
A video storage unit for storing a video signal represented by the limited signal level;
An imaging apparatus comprising: A video reading unit for reading a video signal from a storage medium;
Signal lines for transmitting the three primary color signals of the read video;
A difference calculation unit for calculating a difference in signal level between a specific signal line and another signal line;
A corresponding signal output unit for outputting a corresponding signal corresponding to the calculated difference;
A level limiter for limiting the signal level of the specific signal line by the corresponding signal;
A video display unit for displaying a video represented by the limited signal level;
A storage medium playback device comprising:

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