JP2008118554A - Video signal processor and display device using the same, mobile terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform video signal processing which is complicated to a certain extent, while simplifying a video signal processing circuit used for a mobile terminal. <P>SOLUTION: A portable telephone set 1 includes an antenna 3 for connecting with a public network (network) NT, a television receiving section 5, a camera 7, an operating section 15 and an LCD display section 17. Contents acquired from the public network (network) NT, a broadcast program acquired from the television receiving section 5 and an image captured from the camera 7, and the like can be displayed on the LCD display section 17. As shown in Fig.2, the portable telephone set 1 includes a radio communication section 3 for receiving communication data from the antenna 3 and further, input video signals such as the contents acquired from the public network (network) NT, the broadcast program acquired from the television receiving section 5 and the image captured from the camera 7 are converted into output video signals by performing signal processing thereon by a video signal processing section 27, output to and displayed on the LCD display section 17. Each of the sections is controlled by a control section (CPU) 21. Parameters or the like are stored in a register 25. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video signal processing apparatus, and more particularly to a video signal processing apparatus suitable for a mobile terminal.

  Conventionally, proposals relating to various video processing circuits (video processing devices) have been made. For example, Patent Literature 1 below discloses a saturation enhancement technique that enables sufficient enhancement in a low saturation region while suppressing saturation in a high saturation region when enhancing saturation in an image signal of a digital camera or the like. And an electronic camera using the same has been proposed.

  In Patent Document 1, in the amplification factor calculation circuit, the larger value of the absolute values of the respective values in the color difference signals U and V constituting the image signal is defined as a variable β, and the variable β is a certain value. The calculation result is calculated to be smaller than the calculation result when the change β is smaller than the certain value to obtain the amplification factor α within the determined range, and the amplifiers 372 and 373 use the amplification factor α to obtain the color difference signal. Both U and V are amplified.

As a result, the input / output characteristics of the color difference signals U and V become nonlinear characteristics in which the slope gradually decreases as the variable β increases, and sufficient saturation is applied to the low saturation area while suppressing saturation in the high saturation area. It can be carried out.
JP 2005-150907 A

  9A and 9B are diagrams showing input / output characteristics of the color difference signals U and V using the technique described in Patent Document 1 (FIGS. 5A and 5 of Patent Document 1). corresponding to b)). As shown in FIGS. 9 (a) and 9 (b), the non-linear characteristic is such that the slopes (amplification factor α) gradually decrease as the input values Uin and Vin increase. For example, in FIG. 9A, when a parameter (for example, amplification factor α) whose input / output characteristics are nonlinear can be adjusted, the conversion function can be changed by adjusting the parameter.

  However, for example, in FIG. 9A, when the parameter of 0 to 60 is changed, the conversion function becomes discontinuous unless the parameter of 60 to 128 is also changed. That is, in order to avoid discontinuity, it is necessary to change the parameters of 60 to 128 in accordance with the change of the parameters of input 0 to 60, and there is a problem that the processing becomes complicated. Since the video processing circuit used for the portable terminal needs to maintain its portability (including power saving), the processing in the video processing circuit needs to be as simple as possible. It is necessary to increase the definition of the mounted LCD display section, and it is preferable that the LCD display section can be changed with a degree of freedom that has input / output characteristics.

  An object of the present invention is to perform processing of a complex video signal to some extent while simplifying a video signal processing circuit used in a portable terminal.

  The present invention is characterized by using an algorithm that obtains an output in each of a plurality of conversion functions, compares the values, and selects an output value based on the magnitude relationship. In addition, a video signal processing circuit using this algorithm and a mobile terminal device using the same are provided.

  That is, according to one aspect of the present invention, there is provided a video signal processing circuit having an input / output conversion processing unit that converts an input value into an output value, the first input / output characteristic candidate, and the first input / output characteristic. One or more input / output characteristic candidates having input / output characteristics different from the candidates and having an intersection with the first input / output characteristic candidate, both for an input value smaller than the intersection and an input value larger than the intersection Thus, there is provided a video signal processing circuit including an input / output conversion processing unit having an actual input / output characteristic of either the smaller output value or the larger output value.

  The input value and output value may relate to luminance data Y or color difference data UV in YUV space, and the input value and output value may be red data R, green data G, or blue in RGB space. It may be related to data B.

According to another aspect of the present invention, there is provided a video signal processing circuit having an input / output conversion processing unit that converts an input luminance X into an output luminance Y, and the input / output conversion is performed based on the equations (1) to (3). A video signal processing circuit characterized by performing processing is provided.
Y0 = a × X + c (1)
Y1 = {d × (1-X) +1} × X (2)
Y = min (Y0, Y1) or Y = max (Y0, Y1) (3)

  Here, Expression (1) is a general expression used for luminance conversion, where X is an input, Y is an output, a is a variable parameter for performing contrast adjustment, and c is a variable parameter for performing brightness adjustment. It is. On the other hand, d is a variable parameter for setting the curvature of the quadratic expression shown by the expression (2).

  The present invention may be a portable terminal device including the video signal processing circuit described above and a display unit that displays video based on the video signal processed by the video signal processing circuit. Since the conversion process is simple, the addition of portable terminal devices is reduced, and low power consumption and miniaturization are possible.

  Furthermore, it is preferable to have the 1st operation part which performs operation which changes the said parameter. Furthermore, a second operation unit that performs an operation of determining which one of the smaller or larger output values is to be output may be provided.

  According to the present invention, there is an advantage that continuous input / output characteristics can be obtained even when parameters used in the video signal processing circuit are adjusted. Therefore, the processing in the video signal processing circuit can be simplified, and for example, when used in a mobile terminal device, the mobile terminal device can be reduced in size and power consumption.

  Hereinafter, a video processing circuit according to an embodiment of the present invention and a mobile terminal device using the same will be described with reference to the drawings. FIG. 1 is a diagram illustrating an external configuration example of a mobile phone that is an example of a mobile terminal device according to the present embodiment. 2 is a functional block diagram showing an example of the internal configuration of the mobile phone shown in FIG. 1, FIG. 3 is a functional block diagram showing an example of the configuration of the video signal processing unit, and FIG. 10 is a diagram of the video signal processing circuit. It is a figure which shows the example of 1 circuit structure.

  As shown in FIG. 1, the mobile phone 1 includes an antenna 3 for connecting to a public network (network) NT, a television receiver 5, a camera 7, an operation unit 15, and an LCD display unit 17. Yes. The content acquired from the public network (network) NT, the broadcast program acquired from the television receiver 5, the image acquired from the camera 7, and the like can be displayed on the LCD display unit 17.

As shown in FIG. 2, the cellular phone 1 has a wireless communication unit 3 that receives communication data from the antenna 3, and further, content acquired from the public network (network) NT, acquired from the television receiver 5. An input video signal such as a broadcast program or an image acquired from the camera 7 is subjected to signal processing by the video signal processing unit 27, converted into an output video signal, and output to the LCD display unit 17 for display. Each of these units is controlled by a control unit (CPU) 21. The register 25 stores the conversion parameter. For example, a conversion function as shown below is configured as a dedicated circuit in the video signal processing unit 27 and can be processed.
Y0 = a × X + c (1)
Y1 = {d × (1-X) +1} × X (2)
Y = min (Y0, Y1), Y = max (Y0, Y1) (3)

  FIG. 10 shows an example in which the above equations (1) to (3) are realized by a circuit. As shown in FIG. 10, the parameters a, c, d stored in the register 25 are multiplied by X and a in the multiplier 101, and the multiplied value is added to c in the adder 102, and the comparator 104. (Value of equation (1)).

  On the other hand, X is subtracted from the value “1” by the subtractor 103, d is multiplied by the multiplier 101, “1” is added by the adder 102, and X is further multiplied by the multiplier 101. The This value is input to the comparator 104 as the other output (value of equation (2)).

The values of the above equations (1) and (2) compared by the comparator 104 are output as Y.
In addition, the control unit (CPU) 21 can perform video processing using the conversion function program.

  As shown in FIG. 3, the present invention can be used as, for example, a YUV adjustment unit 33 or a saturation enhancement processing unit 37.

  The above equation (1) is a general equation used for luminance conversion, where X is an input, Y is an output, a is a variable parameter for performing contrast adjustment, and c is a variable parameter for performing brightness adjustment. . On the other hand, d is a variable parameter for setting the curvature of the quadratic expression indicated by the expression (2) newly set in the present embodiment.

  The meaning of the expression (3) means that the output value of the expression (1) and the expression (2) is smaller or larger at the intersection of the expression (1) and the expression (2). It is used as an output value that is continuous across the intersection. 4 to 7 are diagrams illustrating examples of setting input / output characteristics when Expressions (1) to (3) are used. The case where the input / output signal is luminance will be described as an example with reference to FIGS.

  FIG. 4 shows the adjustment contents of the input / output characteristics in which a dark portion of the input X, that is, a portion having a small luminance value is to be brightened strongly, and a bright portion of the input X, that is, a portion having a large luminance value is prevented from overflowing. An example of conversion is shown. Here, a dotted line 51 is a reference line of input X = output Y. A dotted line 55 is a straight line based on the formula (1), and the inclination a and the brightness c are adjusted so as to satisfy the above contents. On the other hand, the dotted line 53 is a curve based on the formula (2), and the curvature d is adjusted to satisfy the above content. By selecting Y = min (Y0, Y1) in Expression (3), input / output characteristics indicated by solid lines 53a and 55a can be obtained.

  Further, if it is desired to adjust the input / output characteristics, the parameters a, c, and d can be changed. However, since Y = min (Y0, Y1) in the expression (3) is selected, these input / output characteristics are changed. The intersection point is automatically selected based on the selected parameter. For this reason, it is possible to finely adjust the dark portion of the input X, that is, the portion having a small luminance value, and to satisfy that the value does not overflow in the bright portion of the input X, that is, the portion having a large luminance value.

  FIG. 5 shows the adjustment contents of the input / output characteristics so that the entire input X, that is, the entire input image, should be brightened, and the bright portion of the input X, that is, the portion having a large luminance value overflows and the image is not over-exposed. An example of conversion is shown. Here, a dotted line 61 is a reference line of input X = output Y. A dotted line 65 is a straight line based on the formula (1), and the inclination a and the brightness c are adjusted to satisfy the above contents. On the other hand, the dotted line 63 is a curve based on the formula (2), and the curvature d is adjusted so as to satisfy the above content. By selecting Y = min (Y0, Y1) in Expression (3), input / output characteristics indicated by solid lines 63a and 65a can be obtained. Further, if it is desired to adjust the input / output characteristics, the parameters a, c, and d can be changed. However, since Y = min (Y0, Y1) in the expression (3) is selected, these input / output characteristics are changed. The intersection point is automatically selected based on the selected parameter. For this reason, it is possible to finely adjust the entire input X, that is, the entire input image, and to satisfy the fact that the bright portion of the input X, that is, the portion having a large luminance value overflows and the image does not become overexposed.

  FIG. 6 shows a case where it is desired to darken the dark portion of the input X, that is, the portion having a low luminance value, and to make the bright portion of the input X, that is, the portion having a large luminance value, not so dark as adjustment contents of the input / output characteristics An example of conversion is shown. Here, a dotted line 71 is a reference line of input X = output Y. A dotted line 75 is a straight line based on the formula (1), and the inclination a and the brightness c are adjusted to satisfy the above contents. On the other hand, the dotted line 73 is a curve based on the formula (2), and the curvature d is adjusted to satisfy the above content. By selecting Y = max (Y0, Y1) in Expression (3), the input / output characteristics indicated by the solid lines 73a and 75a can be obtained. Further, if it is desired to adjust the input / output characteristics, the parameters a, c, and d can be changed. However, since Y = max (Y0, Y1) in the equation (3) is selected, these input / output characteristics are changed. The intersection point is automatically selected based on the selected parameter. For this reason, it is possible to make fine adjustments satisfying that it is desired to darken a dark portion of the input X, that is, a portion having a small luminance value, and that a bright portion of the input X, that is, a portion having a large luminance value is not so dark.

  FIG. 7 shows a conversion example when it is desired to darken the entire input X, that is, the entire input image, and not to darken the bright portion of the input X, that is, the portion having a large luminance value, as the adjustment contents of the input / output characteristics. ing. Here, a dotted line 81 is a reference line of input X = output Y. A dotted line 85 is a straight line based on the formula (1), and the inclination a and the brightness c are adjusted to satisfy the above contents. On the other hand, the dotted line 83 is a curve based on the formula (2), and the curvature d is adjusted to satisfy the above content. By selecting Y = max (Y0, Y1) in Expression (3), the input / output characteristics indicated by the solid lines 83a and 85a can be obtained. Further, if it is desired to adjust the input / output characteristics, the parameters a, c, and d can be changed. However, since Y = max (Y0, Y1) in the equation (3) is selected, these input / output characteristics are changed. The intersection point is automatically selected based on the selected parameter. For this reason, it is possible to make fine adjustments that satisfy that it is desired to darken the entire input X, that is, the entire input image, and that the bright portion of the input X, that is, the portion having a large luminance value is not darkened.

  In all the examples described above, each parameter is selected so that the expression (1) and the expression (2) always have an intersection, but if there is no intersection, the min or the expression (3) Any characteristic is always selected and output by max. In the present embodiment, the equations (1) to (2) need not be limited to this conversion equation. In other words, here, the expression (1) is a linear expression and the expression (2) is a quadratic expression, but any combination of the linear expression or higher may be used, or the conversion expression itself may be a conversion expression having completely different characteristics. I do not care. Even when the parameter is changed, the intersection point moves, but the continuity of the characteristic itself is maintained, so that continuous input / output characteristics can be always obtained, and the conversion function does not become discontinuous. In addition, there is an advantage that it is not necessary to change all the parameters according to the change of one parameter in order to maintain continuity. The parameter has a default value in the register in advance, and can be changed by an input from the operation unit 15. For example, the user can set the parameters, a, c, and d through the operation unit 15. At this time, for example, a parameter may be set by displaying a GUI on a liquid crystal display screen of a mobile phone. The parameters input by the operation unit 15 are stored in the register 25. The parameters stored in the register 25 are output to the video signal processing unit 27 under the control of the control unit 21, and a desired output value is obtained by substituting these parameters into the above formulas (1) to (3). be able to. This output value is used in a display control unit (not shown) to display the display unit.

  If there is no intersection, either characteristic is always selected according to min or max in equation (3).

  Next, a video processing circuit according to a second embodiment of the present invention and a portable terminal using the same will be described with reference to the drawings. FIG. 11 is a diagram showing a circuit configuration example of the video signal processing circuit. Here, n is an integer of 0 or more. Hereinafter, a case where n = 2 will be described as an example.

  In the video processing circuit according to the present embodiment, as shown in FIG. 8A, with respect to the reference line (dotted line) of input X = output Y indicated by reference numeral 91, the first represented by the equation (4). Use the dotted line 93 and the second dotted line 95 expressed by the equation (5) and the third dotted line 97 expressed by the equation (6) to make the small portion of the input X brighter or to increase the large portion of the input X Is when you want to prevent the value from overflowing. The parameters of Expression (4), Expression (5), and Expression (6) are respectively determined, and the min or max is selected as shown in Expression (7) with the intersection as a boundary. In FIG. 8a, the input / output characteristics indicated by the solid lines 93a, 95a, and 97a can be obtained by selecting Y = min (Y0, Y1, Y2) in the equation (7).

As in the case described with reference to FIG. 10, the output values of the following equations (4), (5), and (6) calculated by the multiplier 101 and the adder 102 are input to the comparator 104. These values are compared, and an output value Y is obtained.
Y0 = a0 × X + c0 (4)
Y1 = a1 × X + c1 (5)
Y2 = a2 * X + c2 (6)
Y = min (Y0, Y1, Y2), Y = max (Y0, Y1, Y2) (7)

  For example, FIG. 8B shows an example in which the parameters of one conversion equation from Equation (4) to Equation (6) are further changed. Here, the parameters a1 and c1 in the equation (5) are changed in order to make the large portion of the input X a little larger. Although the dotted line 95 is changed, even if the parameter is changed according to Y = min (Y0, Y1, Y2) in Expression (7), the intersection is automatically determined, and a continuous input / output characteristic is always obtained. Therefore, there is an advantage that even if the parameter is changed, the conversion function does not become discontinuous. In this embodiment, the equations (4) to (6) need not be limited to this conversion equation. In other words, the linear expression is used here, but any combination of the linear expression and higher may be used, and the conversion expression itself may be a conversion expression having completely different characteristics. In addition, there is an advantage that it is not necessary to change all the parameters according to the change of one parameter in order to maintain continuity. Further, since the function is in a simple form, there is an advantage that the conversion process is further simplified.

  Note that the above parameters and whether to select the maximum value or the minimum value are appropriately determined depending on, for example, whether the input video is from a camera, broadcast video, or video from the Internet. You may make it selectable. For example, a table in which input video and parameter values are associated with each other may be stored in a register, and which table value is used in actual input may be determined in advance. You may enable it to switch by user operation later.

  The present invention is applicable to a video signal processing circuit and a portable terminal device using the same.

It is a front view which shows one structural example of the portable terminal by embodiment of this invention. It is a functional block diagram which shows the internal structural example of the portable terminal by embodiment of this invention. FIG. 3 is a functional block diagram illustrating a configuration example of a video signal processing circuit in FIG. 2. It is a figure which shows an example of the input-output characteristic of the video signal processing circuit by the 1st Embodiment of this invention. It is a figure which shows an example of the input-output characteristic of the video signal processing circuit by the 1st Embodiment of this invention. It is a figure which shows an example of the input-output characteristic of the video signal processing circuit by the 1st Embodiment of this invention. It is a figure which shows an example of the input-output characteristic of the video signal processing circuit by the 1st Embodiment of this invention. It is a figure which shows an example of the input-output characteristic of the video signal processing circuit by the 2nd Embodiment of this invention. It is a figure which shows the input / output characteristic of the color difference signals U and V using the technique of patent document 1. FIG. It is a figure which shows an example of the circuit structure by the 1st Embodiment of this invention. It is a figure which shows an example of the circuit structure by the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mobile telephone, NT ... Public network (network), 3 ... Antenna (wireless communication part), 5 ... Television receiver, 7 ... Camera, 15 ... Operation part, 17 ... LCD display part, 27 ... Video signal processing part, DESCRIPTION OF SYMBOLS 21 ... Control part (CPU), 25 ... Register, 31 ... YUV conversion process part, 33 ... YUV adjustment part, 35 ... RGB conversion process part, 37 ... Saturation emphasis process part, 39 ... Gamma correction part, 101 ... Multiplier , 102 ... adder, 103 ... subtractor, 104 ... comparator.

Claims (10)

A video signal processing circuit having an input / output conversion processing unit for converting an input value into an output value,
A first input / output characteristic candidate and one or more input / output characteristic candidates having an input / output characteristic different from the first input / output characteristic candidate and having an intersection with the first input / output characteristic candidate; An image having an input / output conversion processing unit having an actual input / output characteristic of either a small output value or a large output value for both an input value smaller than the intersection and an input value larger than the intersection Signal processing circuit.   Assuming that the actual input / output characteristic is Y and n input / output characteristic candidates (n is an integer) is Yn, Y is selected from the minimum value min or the maximum value max of Yn, that is, Y = 2. The video signal processing circuit according to claim 1, wherein min (Y0, Y1,..., Yn) is obtained by Y = max (Y0, Y1,..., Yn) in the case of a maximum value. .   The input / output characteristic candidate Yn has one or more intersections, and the intersection is automatically selected even when at least one of the plurality of input / output characteristic candidates is changed. Item 3. The video signal processing circuit according to Item 1 or 2.   4. The video signal processing circuit according to claim 1, wherein the input value and the output value relate to luminance data Y or color difference data UV in a YUV space. 5.   4. The video signal processing according to claim 1, wherein the input value and the output value relate to red data R, green data G, or blue data B in an RGB space. 5. circuit. A video signal processing circuit having an input / output conversion processing unit for converting input luminance X to output luminance Y,
6. The video signal processing circuit according to claim 1, wherein input / output conversion processing from X to Y is performed based on the equations (1) to (3).
Y0 = a × X + c (1)
Y1 = {d × (1-X) +1} × X (2)
Y = min (Y0, Y1) or Y = max (Y0, Y1) (3)
Here, the expression (1) is a general expression used for luminance conversion, where X is an input, Y is an output, a is a variable parameter for adjusting contrast, and c is a variable parameter for adjusting brightness. It is. On the other hand, d is a variable parameter for setting the curvature of the quadratic expression shown by the expression (2). Y0 and Y1 are the input / output characteristic candidates, min is a function for selecting the minimum value of the plurality of input / output characteristic candidates, and max is a function for selecting the maximum value of the plurality of input / output characteristic candidates. The video signal processing circuit according to any one of claims 1 to 6,
And a display unit configured to display a video based on the video signal processed by the video signal processing circuit.   The display device according to claim 7, further comprising a first operation unit that performs an operation of changing the parameter.   The display device according to claim 8, further comprising a second operation unit that performs an operation of determining which one of the smaller and larger output values is to be output. A display device according to any one of claims 7 to 9,
A mobile communication terminal including a communication unit that performs communication.

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