JP2009017301A - Signal processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce erroneous correction of white balance adjustment for a video signal. <P>SOLUTION: A signal processing apparatus includes: a white balance target area setting gate section 9 for outputting a white balance target area setting signal in an automatic white system which performs white balance adjustment on a video signal; a color determination processing section 5 for determining whether white balance adjustment is required for a YUV signal after white balance adjustment on the basis of a YUV signal before white balance adjustment and the white balance target area setting signal; and a white balance adjustment gain calculation processing section 6 for calculating a white balance adjustment gain based on results of the determination by the color determination processing section 5, wherein the color determination processing section 5 performs color determination on the YUV signal before white balance adjustment based on a plurality of color determination gate signals with color temperature setting ranges different from each other, and outputs the color determination results. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a signal processing device, and more particularly to an auto white balance system.

  In recent years, the demand for image sensors has increased.

  The video imaged by the image sensor has a color tone that matches the characteristics of the CCD or CMOS image sensor elements. In order to make this a color tone that matches the characteristics of the human eye, various video correction processes are performed in the system. Has been made.

  Among them, the white balance adjustment is based on white with the sun as the light source, for example, white adjustment by adjusting red and blue, etc. with respect to white when using an incandescent bulb, fluorescent lamp, etc. as the light source. Is what you do. This white balance adjustment is generally performed by an auto white balance system (hereinafter referred to as an AWB system).

  In an AWB system that is performed according to the color temperature of a light source, white balance adjustment is performed depending on whether or not the color temperature of the video signal is included within a preset color temperature range to be adjusted. Is called. A signal indicating the set color temperature range is referred to as a color determination gate signal.

  With this color judgment gate signal, the judgment result based on the color temperature is such that the white balance adjustment is performed when the color temperature of the video signal is within the setting range, and the white balance adjustment is not performed when the color temperature is outside the setting range. The white balance can be adjusted to reflect the above (see, for example, Patent Document 1).

  In an image sensor used for a mobile phone or the like, since the effective area of the screen is small, for example, a human face as a subject may occupy most of the screen.

  At that time, a light color temperature such as pale yellow or reddish white such as the face color may be included in the color determination gate signal.

As a result, a subject that does not require white balance adjustment becomes a target of white balance adjustment, and a light-colored subject has a white tone different from the actual color.
JP 2002-31515 A

  The example of the present invention proposes a technique capable of reducing erroneous correction of white balance adjustment for a video signal.

  A signal processing apparatus according to an example of the present invention includes an image sensor that outputs a video signal, and a first multiplier that multiplies the video signal by a first white balance adjustment gain to calculate a video signal after white balance adjustment. A color separation synchronization processing unit that performs color separation of the video signal after white balance adjustment, a YUV matrix processing unit that generates a YUV signal after white balance adjustment from the color-separated video signal, and the first A reciprocal calculation processing unit that outputs a reciprocal conversion value of the white balance adjustment gain, and a YUV signal after white balance adjustment and the reciprocal conversion value are multiplied to calculate a YUV signal before white balance adjustment Multiplier and white balance target area setting signal assigned to each of the plurality of white balance target areas in the image sensor Based on the output white balance target area setting gate unit, the YUV signal before white balance adjustment, and the white balance target area setting signal, the YUV signal after white balance adjustment determines whether or not white balance adjustment is necessary. A color determination processing unit; and a white balance adjustment gain calculation processing unit that calculates a second white balance adjustment gain corresponding to the YUV signal after the white balance adjustment based on the determination result of the color determination processing unit, The color determination processing unit includes performing color determination of the YUV signal before white balance adjustment based on a plurality of color determination gate signals having different color temperature setting ranges.

  According to the example of the present invention, erroneous correction of white balance adjustment for a video signal can be reduced.

  Hereinafter, some embodiments for carrying out examples of the present invention will be described in detail with reference to the drawings.

1. Overview
Embodiments of the present invention relate to an image sensor automatic white balance (AWB) system.

  In the AWB system according to the embodiment of the present invention, color determination for white balance adjustment is performed using a plurality of color determination gate signals having different setting ranges.

  The plurality of color determination gate signals respectively correspond to a plurality of areas in the image sensor set in accordance with the subject to be subjected to white balance adjustment and shooting conditions. Thereby, a color determination gate signal can be selected for each subject and photographing condition.

  Therefore, for example, in an image sensor with a small effective area, white balance adjustment with a color judgment gate signal suitable for a subject where a light-colored part often enters a specific area of the screen, such as a human face. Whether or not is necessary.

  Therefore, according to the embodiment of the present invention, erroneous correction of white balance adjustment for a light-colored subject can be reduced.

2. Embodiment
(1) First embodiment
(A) Overall configuration
FIG. 1 is a block diagram showing the configuration of the AWB system according to the first embodiment of this invention.

  The image sensor 1 outputs a video signal. The image sensor 1 is, for example, a single plate area image sensor, and includes a plurality of pixels. The video signal is composed of red (R), green (G), and blue (B) color signals. The image sensor 1 is composed of, for example, a CCD or CMOS sensor. Each element of the sensors, that is, one pixel is, for example, one of red (R), green (G), and blue (B) by a color filter having an array pattern such as a Bayer method. Each is set to react to only one color. The image sensor 1 may be a three-plate image sensor. In the case of a three-plate image sensor, video signals (incident light) are color-separated into red, green, and blue by mirrors and prisms, and these color signals are input to the three image sensors, respectively.

  The AWB gain multiplier (first multiplier) 2 multiplies the video signal by the white balance adjustment gain, and adjusts the white balance of the photographed video. Therefore, the AWB gain multiplier 2 generates a video signal multiplied by the white balance adjustment gain, that is, a video signal subjected to white balance adjustment.

  The color separation simultaneous processing unit 3 receives a video signal that has been subjected to white balance adjustment, and the input video signal is separated into red (R), green (G), and blue (B) components. The Further, a line memory 3A is provided in the color separation and synchronization processing unit 3. The line memory 3A accumulates signal data for several lines, that is, several times the number of effective pixels in the horizontal direction of the image sensor. When a three-plate area image sensor is used, since color separation has already been performed in the image sensor 1, the color separation simultaneous processing unit 3 performs processing for separating the video signal into each color component. Not done.

  The YUV matrix processing unit 4 generates a YUV signal based on each color-separated signal component. Since this YUV signal is generated from a video signal that has been multiplied by the white balance adjustment gain and subjected to white balance adjustment, it becomes a YUV signal after white balance adjustment (hereinafter referred to as YUV signal after WB adjustment). The YUV signal includes a Y signal (luminance signal) representing the luminance of the video, a U signal that is the difference between the blue component and the luminance signal (Y signal), and a V signal that is the difference between the red component and the luminance signal (Y). .

  The WB-adjusted YUV signal generated by the YUV matrix processing unit 4 is output to the white balance adjustment gain calculation processing unit 6, the multiplier 8, and the video signal processing unit (not shown) at the next stage.

The multiplier 8 multiplies the WB-adjusted YUV signal output from the YUV matrix processing unit 4 and the inverse conversion value output from the inverse calculation processing unit 7 to obtain a YUV signal before white balance adjustment (hereinafter referred to as YUV before WB adjustment). Signal). Here, the reciprocal conversion value output from the reciprocal calculation processing unit 7 is the reciprocal conversion value of the white balance adjustment gain multiplied by the AWB gain multiplier 2. At this time, the reciprocal conversion performed by the reciprocal calculation processing unit 7 is processing in which the reciprocal conversion value = 1 / G when the white balance adjustment gain is G.
That is, the reciprocal calculation processing unit 7 and the multiplier 8 remove the white balance adjustment gain G included in the WB-adjusted YUV signal by multiplying the reciprocal conversion value 1 / G to generate a pre-WB-adjusted YUV signal. it can.
Therefore, in the AWB system having the configuration shown in FIG. 1, it is not necessary to separately provide the color separation and synchronization processing unit 3 including the line memory 3 </ b> A having a large circuit scale dedicated for color determination for generating the YUV signal before WB adjustment. An increase in the circuit scale of the AWB system can be suppressed.
Further, the pre-WB adjustment YUV signal generated from the calculation result of the multiplier 8 is output to the color determination processing unit 5. Thereby, since the color determination by the color determination processing unit 5 can be performed based on the YUV signal before WB adjustment, appropriate color determination and white balance adjustment can be performed.

  A white balance target area setting gate unit (hereinafter referred to as WB target area setting gate unit) 9 performs color determination on a white balance target area setting signal (hereinafter referred to as WB target area setting signal) set by an external device (not shown). Output to the processing unit 5. As will be described later, a plurality of areas to be subjected to white balance adjustment are set in the image sensor 1 according to the subject and shooting conditions, and the WB target area setting signal corresponds to each of these areas. Assigned.

The color determination processing unit 5 determines whether or not the captured video, that is, the video signal input into the AWB system in the area of the image sensor indicated by the WB target area setting signal needs to be adjusted in white balance. The determination is made based on the pre-adjustment YUV signal. Then, the determination result (color determination signal) is output to the white balance adjustment gain calculation processing unit 6.
A white balance adjustment gain calculation processing unit (hereinafter referred to as WB adjustment gain calculation processing unit) 6 calculates a white balance adjustment gain from the YUV signal after WB adjustment from the YUV matrix processing unit 4 based on the color determination result signal. Thereby, the WB adjustment gain calculation processing unit 6 calculates the white balance adjustment gain of the color-determined video signal (pixel).

For example, a UV signal integration unit and an RB gain calculation unit are provided inside the WB adjustment gain calculation processing unit 6. When the color determination processing unit 5 determines that the white balance needs to be adjusted and outputs a color determination result signal, the UV signal integration unit integrates UV signals representing changes in hue and saturation among the YUV signals. . Further, the RB gain calculation unit calculates an R gain (red component gain) and a B gain (blue component gain) based on the calculation result of the UV signal integration unit 5A. The WB adjustment gain calculation unit 6 calculates and outputs a white balance adjustment gain based on the R gain and B gain calculation results.
In the WB adjustment gain calculation processing unit 6 described above, an RB gain integration unit may be provided instead of the UV signal integration unit. In this case, the RB gain calculation unit calculates the R gain and the B gain based on the YUV signal after WB adjustment, the RB gain integration unit performs the integration of the R gain and the B gain, and calculates the white balance adjustment gain from the result. May be performed.
When the color determination processing unit 5 determines that white balance adjustment is unnecessary, the WB adjustment gain calculation processing unit 6 does not calculate the white balance adjustment gain.

  The white balance adjustment gain calculated by the WB adjustment gain calculation processing unit 6 is fed back to the AWB gain multiplier 2 and simultaneously output to the reciprocal calculation processing unit 7.

  As described above, whether or not the white balance adjustment is performed on the video signal is executed based on the color determination result signal output from the color determination processing unit 5. Therefore, in particular, in order to reduce erroneous correction of white balance adjustment for light colors, it is desirable that the AWB system has a configuration that can reduce erroneous determination of color determination by the color determination processing unit 5.

  In the present embodiment, a plurality of color determination gate signals set for white balance adjustment determination are set in different color temperature setting ranges so as to correspond to different subjects and shooting conditions. Features.

Accordingly, color determination can be performed by selecting one color determination gate signal from among a plurality of color determination gate signals according to the subject and shooting conditions, and erroneous determination of color determination can be reduced.
Accordingly, erroneous correction of white balance adjustment for a light subject can be reduced.

  Hereinafter, the color determination processing unit 5 that can perform color determination of a video signal using a plurality of color determination gate signals will be described.

(B) Configuration of the color determination processing unit
The color determination processing unit according to the first embodiment of the present invention will be described with reference to FIG.

  A YUV signal before WB adjustment is input into a color determination processing unit 5 of this embodiment shown in FIG. 2 via a YUV signal input terminal 51 before white balance adjustment (hereinafter referred to as a YUV signal input terminal before WB adjustment). The The input pre-WB adjustment YUV signals are color-coded by a plurality of color determination gate signals having different color temperature setting ranges by a plurality of color determination gate signal processing units 53A to 53D provided in the color determination processing unit 5. Determined.

  Each of the color determination gate signal processing units 53A to 53D includes one color determination setting register 54A to 54D and one color determination unit 55A to 55D.

  In the color determination gate signal setting registers 54A to 54D, for example, a plurality of color determination gate signals output from an external device (not shown) are stored, respectively.

  Here, the color determination gate signal of the present embodiment will be described with reference to FIGS.

  FIG. 3 shows a basic color determination gate signal in this embodiment.

  As shown in FIG. 3, the color determination gate signal is set by, for example, a color difference signal, that is, a UV coordinate system. In this UV coordinate system, the vicinity of the center of the coordinates is a white range. The U axis shows the strength of the U signal (BY component), which corresponds to a change in color temperature from yellow to blue. In the example illustrated in FIG. 3, it is determined whether or not the UV component of the pre-WB adjustment YUV signal of the video signal to be determined is within a range of U1 ≦ U ≦ U2, for example.

  The V axis indicates the strength of the V signal (R−Y component), which corresponds to a change in color temperature from cyan to red. In the present embodiment, it is determined whether or not the UV component of the pre-WB adjustment YUV signal of the video signal to be determined is within a range of V1 ≦ V ≦ V2, for example.

  Further, the UV coordinate system also includes color components of orange-cyan signal (I signal) and green-magenta signal (Q signal). In the present embodiment, in order to reflect these color components in the color determination, a setting range for these color temperatures is also provided. The setting range is set by straight lines L1 and L2.

That is, the area 20 surrounded by the thick line in FIG. 3 serves as a color determination gate signal, and color determination for white balance adjustment is performed depending on whether or not a video signal is included in the area 20.
In the present embodiment, based on the color determination gate signal shown in FIG. 3, different color determination gate signals are set according to the subject and the shooting conditions.

FIG. 4 shows an example of the color determination gate signal in the present embodiment.
In the present embodiment, for example, when the video signal includes a signal indicating reddish white like a human face, the YUB signal before WB adjustment is included in the color determination gate signal, and the white balance adjustment target. Therefore, the color determination gate signal is set so that the white balance adjustment does not cause an erroneous correction that impairs the color tone of the original video signal.
Therefore, for example, as shown in FIG. 4, the color determination gate signal in which the color temperature setting range is narrowed so that the color determination gate signal does not include the color temperature range (region 21) indicating reddish white. 20A is set.

Accordingly, when the color determination gate signal shown in FIG. 4 determines the color of the pre-WB YUV signal indicating reddish white, the pre-WB adjustment YUV signal is not included in the color determination gate signal 21A. can do.
Therefore, according to the color determination gate signal shown in FIG. 4, the pre-WB YUV signal indicating reddish white is determined to require no white balance adjustment, and the light color such as reddish white of the video signal is The color tone can be kept.

  Further, as shown in FIG. 5, the basic color determination gate signal 20 has a color temperature range different from that in FIG. 4 so that any one of the regions 22 to 24 in the predetermined color temperature range is not included. A plurality of color determination gate signals are set.

  4 and FIG. 5 are output from the color determination gate signal setting registers 54A to 54D to the color determination units 55A to 55D in the color determination gate signal processing units 53A to 53D, respectively. .

Then, based on the plurality of color determination gate signals set as in the examples shown in FIGS. 4 and 5, the color determination units 55 </ b> A to 55 </ b> D convert the UV component of the input YUV signal before WB adjustment into a color determination gate. It is determined whether or not it is included in the signal. Each of the color determination units 55 </ b> A to 55 </ b> D performs color determination of the UV component of the YUV signal before WB adjustment for each pixel, and outputs the color determination result to the selector 56.
Based on the selection signal, the selector 56 selects one color determination result corresponding to the subject and the shooting conditions from the plurality of color determination results input to the selector 56.
In the present embodiment, the selection signal is a WB target area setting signal output from the white balance target area setting gate unit (hereinafter, WB target area setting gate unit) 9.

  This WB target area setting signal indicates a plurality of areas that are targets of white balance adjustment set in the image sensor 1 in accordance with the subject and shooting conditions. The WB target area setting signal corresponds to the color determination gate signal described above.

The WB target area setting signal will be described more specifically with reference to FIG.
As shown in FIG. 6, for example, the image sensor 1 is covered with a frame such as a casing on which the image sensor 1 is mounted, and does not substantially function as a sensor, and a video signal (incident light). The screen effective area 11 functions as a sensor.

The screen effective area 11 is divided into, for example, 3 × 5 = 15 divided areas a0 to a15. In the image sensor 1 used for a mobile phone or the like, the size of the screen effective area 11 is smaller than the size of the screen invalid area 10. For this reason, subjects such as human faces often fall within a specific divided area.
Therefore, for example, in order to perform white balance adjustment according to the subject and shooting conditions such as a human face, sky, white wall, or snowy field, a plurality of WB target areas are configured by combining the divided areas. The WB target areas A to D are recognized by the AWB system as targets for white balance adjustment.

  For example, the WB target area A is configured by three divided areas a6, a7, and a8 in the central portion of the screen effective area 11 among the screen effective areas. The WB target area B is composed of five divided areas a2, a6, a7, a8, and a12 arranged in a cross shape in the screen effective area 11, and the WB target area C is arranged in a square shape. 3 × 3 = 9 divided areas a1, a2, a3, a6, a7, a8, a11, a12, a13. The WB target area D is composed of seven divided areas a2, a5, a6, a7, a8, a9, and a12.

  For example, the WB target area A is set so as to correspond to the color determination gate signal 21 shown in FIG. 4, and similarly, a plurality of color determination gate signals having different color temperature setting ranges from the WB target areas BD. Are set to correspond to each other.

  The setting information of these WB target areas A to D is stored in a WB target area setting register 92 provided in the WB target area setting gate unit 9. Then, a WB target area corresponding to the subject and shooting conditions is selected by an external device (not shown). A WB target area setting signal (for example, 2 bits) corresponding to the selected WB target area is output from the WB target area setting signal generation unit 92 to the selector 56 as a selection signal.

  Based on the WB target area setting signal as the selection signal, one of the determination results output from the color determination gate signal processing units 53A to 53D is selected. The selected color determination result is output to an AND gate 57 provided in the color determination processing unit 5.

A screen valid area setting register 52 is provided in the color determination processing unit 5. In this register 52, a screen valid area setting signal (for example, 1 bit) indicating either the screen invalid area 10 or the screen valid area 11 is stored.
This screen effective area setting signal is output to the AND gate 57. That is, the AND gate 57 determines whether or not the pixels determined by the color determination gate signal processing units 53 </ b> A to 53 </ b> D are pixels included in the screen effective area 11.

  The color determination result signal that is the output of the AND gate 57 is output to the WB adjustment gain calculation processing unit 6 via the color determination result output terminal 58.

When the color determination result signal indicates a determination result for white balance adjustment, the white balance adjustment gain is calculated by the WB adjustment gain calculation processing unit 6.
In addition, when the color determination result signal indicates a determination result in which white balance adjustment is not performed, or when the color-determined pixel is in the screen invalid area 10, the white balance adjustment gain is not calculated.

  In the present embodiment, the signal output via the AND gate 57 is the color determination result signal. However, the signal selected by the selector 56 without the AND gate 57 being provided is the color determination result signal. The result may be output directly to the result output terminal 58 and used as a color determination result signal.

  As described above, in the AWB system according to the first embodiment of the present invention, the color determination processing unit 5 determines the color determination gate for determining whether the video signal is within the range of the color temperature subject to white balance adjustment. A plurality of signal processing units are provided. Different color temperature ranges are assigned to the plurality of color determination gate signals respectively input to the plurality of color determination gate signal processing units.

  In the image sensor 1, a plurality of WB target areas are set according to the subject and shooting conditions, and the plurality of color determination gate signals and the plurality of WB target areas respectively correspond to the subject and shooting conditions. .

Therefore, according to the first embodiment of the present invention, the screen effective area is obtained by performing the color determination of the video signal by the plurality of color determination gate signals respectively corresponding to the plurality of WB target areas in the image sensor. As in the case of a small image sensor, it is possible to perform color determination suitable for a subject and photographing conditions in which a light color often occupies a specific portion in the image sensor.
Accordingly, erroneous correction of white balance adjustment for the video signal can be reduced.

(B) Operation
The operation of the AWB system according to the first embodiment of the present invention will be described below.

  First, the video signal output from the image sensor 1 is multiplied by a white balance adjustment gain (first white balance adjustment gain) by an AWB gain multiplier 2. Thereafter, the video signal multiplied by the WB adjustment gain is output to the color separation and synchronization processing unit 3.

  The video signal is input to the color separation and synchronization processing unit 3, and after color separation and synchronization, the YUV matrix processing unit 4 converts the video signal into a YUV signal. Since the YUV signal at this time is obtained from the video signal multiplied by the WB adjustment gain by the AWB gain multiplier 2, it becomes a YUV signal after WB adjustment.

  The WB-adjusted YUV signal is output to the WB adjustment gain calculation processing unit 6, the multiplier 8, and the video signal processing unit (not shown) at the next stage.

  Further, the white balance adjustment gain is input to the reciprocal conversion processing unit 7. The white balance adjustment gain is subjected to reciprocal calculation processing by the reciprocal conversion processing unit 6, and the reciprocal conversion value corresponding to the white balance adjustment gain is output to the multiplier 8.

  The inverse conversion value and the WB-adjusted YUV signal output from the YUV matrix processing unit 4 are multiplied by the multiplier 8. Since the WB-adjusted YUV signal is a YUV signal multiplied by the white balance adjustment gain, the white balance adjustment included in the WB-adjusted YUV signal is further multiplied by the inverse conversion value that is the inverse of the white balance adjustment gain. The gain is removed and a YUV signal before white balance adjustment is generated.

  According to the AWB system shown in FIG. 1, the reciprocal conversion value is obtained from the white balance adjustment gain, and multiplied by the YUV signal after white balance adjustment, the YUV signal before WB adjustment is reproduced. Therefore, the color determination processing unit 5 determines whether or not the target pixel needs to be white balance adjusted based on the YUV signal before WB adjustment without providing a large circuit memory dedicated for the color determination processing unit 5. Can do.

The generated pre-WB adjustment YUV signal is output to the color determination processing unit 5, and based on the YUV signal, color determination is performed as to whether or not white balance adjustment is to be performed.
The pre-WB adjustment YUV signal input to the color determination processing unit 5 is sent to a plurality of color determination gate signal processing units provided in the color determination processing unit 5 via the pre-WB adjustment YUV signal input terminal 51 shown in FIG. Input to 53A to 53D, respectively.

Then, the color determination units 55A to 55D respectively determine whether or not the pre-WB adjustment YUV signal is included in different color determination gate signals stored in the color determination gate signal setting registers 54A to 54D.
In the color determination units 55A to 55D, it is determined whether or not the UV component of the YUV signal before WB of one pixel is included in the color determination gate signal indicated by the UV coordinate system. Then, the UV values of the pixels included in the color determination gate signal are sequentially integrated, and the integrated value is compared with a preset reference value to determine whether or not to perform white balance adjustment.

  Each of the color determination results obtained by the color determination units 55 </ b> A to 55 </ b> D is output to the selector 56. The selector 56 receives the WB target area setting signal output from the WB target area setting gate unit 9.

  Then, using the WB target area setting signal set according to the subject and the shooting conditions as a selection signal, one color determination result is selected from the plurality of color determination results by the selector 56 and output to the AND gate 57. The

  A screen valid area setting signal is output from the screen valid area setting register 52 to the AND gate 57.

The AND gate 57 outputs a color determination result signal based on the two inputs. Here, when the target pixel for color determination is a pixel in the screen effective area, a signal reflecting the color determination result is output. That is, when a determination result for white balance adjustment is obtained, a signal for performing white balance adjustment (for example, a “1” signal) is output, and for a determination result for which white balance adjustment is not performed, white balance adjustment is performed. A signal that is not subjected to balance adjustment (for example, a “0” signal) is output.
When the target pixel for color determination is not a pixel within the effective screen area, a signal (for example, “0” signal) that does not perform white balance adjustment is output regardless of the color determination result.

  Then, an output from the AND gate 57 as a color determination result signal is output to the WB adjustment gain calculation processing unit 6 via the color determination result output terminal 58.

  Then, based on the color determination result signal, the WB-adjusted YUV signal input into the WB adjustment gain calculation processing unit 6 is subjected to arithmetic processing to calculate a white balance adjustment gain (second white balance adjustment gain). Is done.

  The calculated white balance adjustment gain is output to the reciprocal arithmetic processing unit 7 and fed back to the AWB gain multiplier 2 together with the gain.

  As a result, the video signal input from the image sensor 1 into the AWB system is adjusted in white balance.

As described above, according to the first embodiment of the present invention, the video signal is color-determined by the plurality of color determination gate signals respectively corresponding to the plurality of WB target areas in the image sensor. As in an image sensor with a small area, suitable color determination can be performed on a subject whose light color often occupies a specific portion in the image sensor.
Therefore, erroneous correction of white balance adjustment for the video signal can be suppressed.

(2) Second embodiment
A second embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the first embodiment, it is determined whether a plurality of color determination gate signals having different color temperature setting ranges include a YUV signal before WB adjustment of a pixel to be subjected to white balance. An AWB system that performs white balance adjustment suitable for conditions has been described.

  However, the present invention is not limited to this, and it is possible to reduce the erroneous determination of the color determination by excluding the predetermined subject and the video signal of the shooting condition that are likely to cause the erroneous determination of the color determination from the target of the color determination. .

  For example, as shown in FIG. 7, the color determination gate signal is input into one color determination gate signal processing unit 59 among the plurality of color determination gate signal processing units 54 </ b> A to 54 </ b> C and 59 in the color determination processing unit 5. No color determination gate signal setting register is provided.

  Thereby, a predetermined WB target area can be excluded from the target of color determination by the color determination gate signal. It should be noted that an area excluded from the color determination target may be set in advance so that one of whether to perform white balance adjustment is selected.

  Therefore, the video signal in the predetermined WB target area is not subject to color determination, and erroneous color determination is not performed.

  Therefore, appropriate color correction can be performed on a subject whose light color often occupies a specific portion in the image sensor under a predetermined subject and photographing conditions.

  In the present embodiment, an example in which one WB target area is excluded from the color determination target has been described. However, the present invention is not limited thereto, and two or more WB target areas may be excluded from the color determination target. .

As described above, according to the second embodiment of the present invention, the color determination of the video signal is performed by the plurality of color determination gate signals respectively corresponding to the plurality of WB target areas in the image sensor, and the predetermined WB is determined. By excluding the target area from the target of color determination, suitable color determination can be performed for a subject whose light color often occupies a specific part in the image sensor, such as an image sensor with a small effective screen area. it can.
Accordingly, erroneous correction of white balance adjustment for the video signal can be reduced.

(3) Third embodiment
In the first and second embodiments, the AWB system has been described that performs color determination using a plurality of color determination gate signals by hardware and outputs a color determination result corresponding to the set WB target area.

  However, the present invention is not limited to this, and color determination may be performed by setting a plurality of color determination gate signals by software.

  FIG. 8 shows an internal configuration of the color determination processing unit 5 according to the third embodiment of the present invention.

  As shown in FIG. 8, the color determination processing unit 5 is provided with a calculation unit 5A and a control unit 5B.

  The pre-WB adjustment YUV signal and the WB target area setting signal are input to the calculation unit 5A.

  The control unit 5B has software for calculating setting data of a plurality of color determination gate signals corresponding to the WB target area and the color determination result of the YUV signal before WB adjustment by the color determination gate signal.

  The control unit 5B causes the calculation unit 5A to execute the color determination process shown in FIG.

  First, the YUV signal before WB adjustment and the WB target area setting signal are input into the color determination processing unit 5, and the calculation unit 5A captures them (ST1).

  Next, the control unit 5B selects one color determination gate signal corresponding to the input WB target area setting signal from the plurality of color determination gate signals, and outputs it to the calculation unit 5A. Then, the control unit 5B causes the calculation unit 5A to perform color determination as to whether or not the selected color determination gate signal includes the UV component of the input pre-WB adjustment YUV signal (ST2).

  Then, the color determination result by the calculation unit 5A is output from the calculation unit 5A to the WB adjustment gain calculation processing unit 6 shown in FIG. 1, and the calculation process by software ends (ST3).

  Through the above steps, the color determination of the video signal can be performed by selecting a color determination gate signal corresponding to the subject and shooting conditions from among a plurality of color determination gate signals having different settings by using software.

  In the third embodiment of the present invention, a plurality of different color determination gate signals are set by software, one color determination gate signal corresponding to the subject and shooting conditions is selected, and the color determination gate signal is included in the color determination gate signal. It is determined whether or not a video signal is included.

Therefore, for a subject whose light color often occupies a specific part in the image sensor, such as an image sensor with a small screen effective area, by a plurality of color determination gate signals respectively corresponding to a plurality of WB target areas in the image sensor. On the other hand, suitable color determination can be performed.
Therefore, as in the third embodiment of the present invention, it is possible to reduce erroneous correction of white balance adjustment for a video signal also by a color determination processing unit using software.

  The example of the present invention is not limited to the first to third embodiments described above, and can be embodied by modifying each component without departing from the gist thereof. Various inventions can be configured by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some constituent elements may be deleted from all the constituent elements disclosed in the above-described embodiments, or constituent elements of different embodiments may be appropriately combined.

The block diagram which shows the whole structure of a signal processing apparatus. The block diagram which shows the internal structure of the color determination process part of 1st Embodiment. The figure which shows the basic example of a color determination gate signal. FIG. 5 is a diagram illustrating an example of a color determination gate signal according to the first embodiment. FIG. 5 is a diagram illustrating an example of a color determination gate signal according to the first embodiment. The figure which shows the structural example of a white balance object area. The figure which shows the internal structure of the color determination process part of 2nd Embodiment. The figure which shows the internal structure of the color determination process part of 3rd Embodiment. 10 is a flowchart illustrating the operation of a color determination processing unit according to the third embodiment.

Explanation of symbols

  1: image sensor, 2: AWB gain multiplier, 3: color separation synchronization processing unit, 4: YUV matrix processing unit, 5: color determination processing unit, 6: white balance adjustment gain calculation processing unit, 7: reciprocal conversion processing Part: 8: second multiplier, 9: white balance target area setting gate part, 10: screen invalid area, 11: screen valid area, 20, 20A: color determination gate signal, A to D: white balance target area, 51: YUV signal input terminal before white balance adjustment, 52: Screen effective area setting register, 53A to 53D, 59: Color determination gate signal processing unit, 54A to 54D: Color determination gate signal setting register, 55A to 55D: Color determination unit , 56: selector, 57: AND gate, 58: color determination result output terminal, 5A: arithmetic unit, 5B: control unit, 91: white balance target Rear setting register, 92: White balance target area setting signal generator.

Claims (5)

An image sensor that outputs a video signal;
A first multiplier for multiplying the video signal by a first white balance adjustment gain and calculating a video signal after white balance adjustment;
A color separation synchronization processing unit for performing color separation of the video signal after the white balance adjustment;
A YUV matrix processing unit for generating a YUV signal after white balance adjustment from the color-separated video signal;
A reciprocal calculation processing unit for outputting a reciprocal conversion value of the first white balance adjustment gain;
A second multiplier that multiplies the YUV signal after white balance adjustment and the reciprocal transformation value to calculate a YUV signal before white balance adjustment;
A white balance target area setting gate unit that outputs a white balance target area setting signal assigned to each of the plurality of white balance target areas in the image sensor;
A color determination processing unit that determines whether or not the white balance adjustment is necessary based on the YUV signal before the white balance adjustment and the white balance target area setting signal;
A white balance adjustment gain calculation processing unit that calculates a second white balance adjustment gain corresponding to the YUV signal after the white balance adjustment based on the determination result of the color determination processing unit;
The signal processing apparatus, wherein the color determination processing unit performs color determination of the YUV signal before white balance adjustment based on a plurality of color determination gate signals having different color temperature setting ranges. The plurality of white balance target areas are set in the image sensor differently according to the video signal,
The signal processing apparatus according to claim 1, wherein the plurality of white balance target areas correspond to the plurality of color determination gate signals, respectively. The color determination processing unit
A plurality of color determination gate signal inputs, respectively, a plurality of color determination gate signal processing units that respectively output color determination results of the input color determination gate signal and the YUV signal before white balance adjustment;
A selector that selects one color determination result from a plurality of color determination results output from the plurality of color determination gate signal processing units using the white balance target area setting signal as a selection signal; The signal processing apparatus according to claim 1 or 2.   Among the plurality of color determination gate signal processing units, at least one color determination gate signal processing unit does not receive a color determination gate signal and excludes a predetermined white balance target area from the color determination target. The signal processing device according to any one of claims 1 to 3. The color determination processing unit
A control unit and a calculation unit;
The control unit inputs the YUV signal and the white balance target area setting signal before the white balance adjustment to the arithmetic unit;
Performing color determination of the YUV signal before white balance adjustment with a color determination gate signal corresponding to the white balance target area setting signal;
The signal processing apparatus according to claim 1, wherein a step of outputting a color determination result signal to the white balance adjustment gain calculation processing unit is executed based on the result of the color determination.

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