JP2009253632A - Image processing apparatus, image processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of detecting up-converted cross-color interference, relating to Y/C separation, on the basis of input image signals, and to provide an image processing method and a program. <P>SOLUTION: The image processor includes: a color vector deriving part for deriving a color vector, on the basis of input color signals; a color vector holding part for holding the color vector derived by the color vector deriving part; an inner product deriving part for deriving the inner product value of the color vector, on the basis of a first color vector corresponding to a present frame derived by the color vector deriving part and a second color vector corresponding to a previous frame held in the color vector holding part; and a cross-color interference decision part for deriving the degree of occurrence of the cross-color interference, on the basis of the first vector, the second vector and the inner product value derived by the inner product deriving part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing device, an image processing method, and a program.

  In recent years, digital television television broadcasting (hereinafter referred to as “digital broadcasting”) has been started as a television broadcasting that replaces analog television television broadcasting (hereinafter referred to as “analog broadcasting”). Display devices capable of receiving broadcasts are becoming widespread.

  In analog broadcasting, a so-called composite signal in which a luminance signal (Y) and a color signal (C) are combined is used to increase the transmission efficiency of an image signal. Therefore, in analog broadcasting, the received image signal is separated into a luminance signal (Y) and a color signal (C) by performing Y / C separation on the side of the receiver such as a display device. An image corresponding to the received image signal is displayed on the display screen. Here, when the performance of Y / C separation in the receiver is low, the color signal (C) is mixed into the luminance signal (Y), thereby causing “dot interference” or the color signal (C ) Mixed with the luminance signal (Y) causes “cross color interference”. Since dot interference and cross color interference are a kind of noise, if they occur, the image quality is impaired.

  Under such circumstances, a technique for performing Y / C separation more reliably has been developed. As a technique for performing Y / C separation using a one-dimensional filter, a two-dimensional filter, and a three-dimensional filter, for example, Patent Document 1 can be cited.

Japanese Patent No. 3240711

  In contrast to the analog broadcast in which the composite signal is transmitted and Y / C separation is performed on the receiver side, in the digital broadcast, each of the luminance signal (Y) and the color signal (C) is transmitted from a broadcast station or the like. In digital broadcasting, a higher definition HD (High Definition) resolution image signal is transmitted from a broadcasting station or the like instead of an SD (Standard Definition) resolution image signal used in analog broadcasting. Here, the image signals transmitted from a broadcasting station or the like in digital broadcasting are not all HD resolution image signals, but the SD resolution image signals used in conventional analog broadcasting are up-converted to HD resolution. In some cases, a pseudo HD resolution image signal (scaled image signal; hereinafter, also referred to as “pseudo HD resolution image signal”) may be included.

  When a pseudo HD resolution image signal is transmitted, Y / C separation, up-conversion from an SD resolution image signal to an HD resolution image signal, and a signal format at the image signal supply source such as a broadcasting station Conversion is performed. Then, each of the luminance signal (Y) and the color difference signal (UV) is transmitted from, for example, a broadcasting station. Here, Y / C separation is not always performed using a conventional technique that performs Y / C separation more reliably at an image signal supplier such as a broadcasting station. Therefore, for example, in a receiver that receives a digital broadcast, there is a possibility that a cross color interference has already occurred and an image signal in which the generated cross color interference has deteriorated due to enlargement (that is, the image quality has deteriorated) may be received. . Here, the cross color interference is noise generated when a luminance signal component is mixed into a color signal, and appears on the image as, for example, rainbow pattern noise (colored moire).

  In addition, in the pseudo HD resolution image signal in which the cross color interference occurs, the nature of the image signal related to the occurrence of the cross color interference changes from the SD resolution image signal due to, for example, up-conversion. Examples of the change in the property of the image signal related to the occurrence of the cross color interference include, for example, “the property that the cross color interference component is inverted for each line is lost” or “the spatial frequency of the cross color interference component is changed. To do ". Therefore, for the pseudo HD resolution image signal, “a detection method using the property that the cross color interference component is inverted for each line”, which is an effective detection method of cross color interference in the SD resolution image signal (for example, Even if the method of “filtering in the vertical direction)” is used, the occurrence of “up-converted cross-color interference related to Y / C separation” cannot be detected. Similarly, for a pseudo HD resolution image signal, “a detection method for detecting cross color interference based on a predetermined spatial frequency component (for example, a method using a band-pass filter)”. "Cannot be used to detect the occurrence of" up-converted cross-color interference related to Y / C separation ".

  Here, when “up-converted cross-color interference related to Y / C separation” cannot be detected, for example, the cross-color interference cannot be reduced, and image quality is deteriorated. Therefore, a method for detecting “upconverted cross-color interference associated with Y / C separation” has been desired.

  The present invention has been made in view of the above problems, and an object of the present invention is to detect up-converted cross color interference related to Y / C separation based on an input image signal. An object is to provide a new and improved image processing apparatus, an image processing method, and a program that are possible.

  In order to achieve the above object, according to a first aspect of the present invention, a color vector deriving unit for deriving a color vector based on an input color signal inputted, and a color vector derived by the color vector deriving unit Based on the color vector holding unit to hold, the first color vector corresponding to the current frame derived by the color vector deriving unit, and the second color vector corresponding to the previous frame held in the color vector holding unit, The degree of occurrence of cross color interference is derived based on the inner product deriving unit for deriving the inner product value of the color vector, the first vector, the second vector, and the inner product value derived by the inner product deriving unit. An image processing apparatus including a cross-color interference determination unit is provided.

  With this configuration, it is possible to detect up-converted cross-color interference related to Y / C separation based on the input image signal.

  In addition, the input color signal and the smoothed color signal smoothed by the filter are mixed based on the determination result in the cross color interference determination unit and the filter that smoothes the input color signal in the time axis direction. A gain setting unit that sets a gain value that defines a ratio for each pixel; and a mixing unit that mixes the input color signal and the smoothed color signal for each pixel based on the gain value set for each pixel. May be provided.

  With this configuration, the up-converted cross-color interference related to Y / C separation is detected based on the input image signal, and the detected up-converted cross-color interference is reduced, thereby improving the image quality. be able to.

  The gain setting unit further includes a motion detection unit that detects a motion amount for each pixel based on a correlation between the input luminance signal corresponding to the input current frame and the previous frame input luminance signal corresponding to the previous frame. The unit may further set the gain value for each pixel based on the motion amount detected by the motion detection unit.

  With this configuration, it is possible to more reliably prevent erroneous detection of up-converted cross color interference.

  Further, the image processing apparatus further includes a cross color interference generation condition detection unit that detects, for each pixel, a pixel that satisfies a condition that causes cross color interference based on the input luminance signal, and the gain setting unit further includes the cross color interference generation condition. The gain value may be set for each pixel based on the detection result of the detection unit.

  With this configuration, the up-converted cross color interference can be reduced with higher accuracy for each pixel.

  The smoothing color signal further includes a gain suppression unit that multiplies the gain suppression value corresponding to the absolute value of the smoothing color signal for each pixel, and the mixing unit includes the input color signal, The smoothed color signal multiplied by the gain suppression value may be mixed for each pixel.

  With this configuration, the influence of up-converted cross color interference can be reduced.

  In order to achieve the above object, according to a second aspect of the present invention, the color derived in the step of deriving a color vector based on the input color signal inputted and the step of deriving the color vector Based on the step of holding a vector, the first color vector corresponding to the current frame derived in the step of deriving the color vector, and the second color vector corresponding to the previous frame held in the step of holding Degree of occurrence of cross-color interference based on the inner product value derived in the step of deriving the inner product value of the color vector, the first vector, the second vector, and the step of deriving the inner product value An image processing method is provided.

  By using such a method, it is possible to detect an up-converted cross color interference related to Y / C separation based on an input image signal.

  In order to achieve the above object, according to a third aspect of the present invention, a color vector derived in a step of deriving a color vector based on an input color signal input and a step of deriving the color vector Based on the first color vector corresponding to the current frame derived in the step of deriving, the step of deriving the color vector, and the second color vector corresponding to the previous frame retained in the step of retaining Deriving the degree of occurrence of cross-color interference based on the step of deriving the inner product value of the vectors, the first vector, the second vector, and the inner product value derived in the step of deriving the inner product value. A program for causing a computer to execute the steps is provided.

  With such a program, it is possible to detect up-converted cross color interference related to Y / C separation based on the input image signal.

  According to the present invention, it is possible to detect an up-converted cross color interference related to Y / C separation based on an input image signal.

  Exemplary embodiments of the present invention will be described below 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.

(Configuration example of image processing system according to an embodiment of the present invention)
First, an example of the configuration of an image processing system according to an embodiment of the present invention will be described. FIG. 1 is an explanatory diagram showing an example of the configuration of an image processing system according to an embodiment of the present invention.

  Referring to FIG. 1, an image processing system according to an embodiment of the present invention receives and receives (or receives) an image signal transmitting device (reference numerals 10, 20, 30,... And a display device 100 that displays an image based on the image signal. Here, the image signal transmission device and the display device 100 according to the embodiment of the present invention are connected by wireless / wired respectively.

  An image signal transmission apparatus according to an embodiment of the present invention transmits an HD resolution image signal. At this time, the image signal transmission apparatus according to the embodiment of the present invention selectively performs Y / C separation and up-conversion according to the image signal to be transmitted. More specifically, the image signal transmission apparatus according to the embodiment of the present invention performs an Y / C separation and an up-conversion when an image signal to be transmitted is an SD resolution image signal, thereby performing an HD resolution image. A signal or a pseudo HD resolution image signal is transmitted.

  Here, as the image signal transmission apparatus according to the embodiment of the present invention, for example, a broadcasting station 10 (or a television tower) that transmits an image signal related to digital broadcasting, a Y / C separation function, and an up-conversion function are provided. An image reproducing apparatus 20, 30,... That outputs an image signal indicating an image reproduced by reproducing the image data. As the image reproducing devices 20, 30,..., For example, a computer such as a PC (Personal Computer), a disc such as a Blu-ray (registered trademark) disc player (or Blu-ray (registered trademark) recorder), a DVD recorder, etc. A game machine such as a playback device or PlayStation (registered trademark) series may be used, but the present invention is not limited thereto.

  The display device 100 detects the up-converted cross-color interference related to Y / C separation for each pixel based on the input image signal. Further, for example, based on the detection result of the cross color interference, the display device 100 performs image processing for reducing the up-converted cross color interference (noise) related to Y / C separation on the input image signal. . Then, the display device 100 displays, for example, an image corresponding to the image signal with the reduced up-converted cross color interference and the detection result of the up-converted cross color interference on the display screen. That is, the display device 100 also serves as an image processing device that processes an input image signal. It should be noted that the configuration example of the display device 100 and image processing according to the embodiment of the present invention (upconverted cross color interference detection processing and cross color interference upconverted based on the detection result of cross color interference are reduced. Will be described later.

  In the image processing system according to the embodiment of the present invention, the image signal transmission device transmits an HD resolution image signal or a pseudo HD resolution image signal. In the image processing system according to the embodiment of the present invention, the display device 100 that has received the image signal performs up-converted cross-color interference related to Y / C separation for each pixel based on the input image signal. To detect.

  As described above, when the input image signal is a pseudo HD resolution image signal, the property of the image signal related to the occurrence of cross color interference changes from the SD resolution image signal. For this reason, the conventional cross-color interference detection method that is effective in the image signal of SD resolution cannot detect the up-converted cross-color interference. Therefore, the display device 100 does not use the conventional cross color interference detection method that is effective for the SD resolution image signal, but uses the cross color interference detection method according to an embodiment of the present invention described later, thereby up-converting. Detect cross color interference. Therefore, the display device 100 can detect the up-converted cross color interference that cannot be detected by the conventional method for detecting cross color interference.

  Further, the display device 100 attempts to reduce, for example, up-converted cross color interference (noise) based on the detection result using the cross color interference detection method according to the embodiment of the present invention. Therefore, the image processing system according to the embodiment of the present invention can improve the image quality of the image displayed on the display screen of the display device 100.

  Hereinafter, a display device according to an embodiment of the present invention will be described. In the following description, it is assumed that the display device according to the embodiment of the present invention performs image processing on an input image signal and displays an image corresponding to the image signal after image processing on a display screen. The embodiment is not limited to such a configuration. In an embodiment of the present invention, a display device according to an embodiment of the present invention shown below is an image processing device independent of a display device that displays an image (for example, a configuration in which an image processing unit shown below is an independent device) ). That is, the display device according to the embodiment of the present invention described below can be replaced with an image processing device. Hereinafter, for convenience of explanation, a case where the image processing apparatus according to the embodiment of the present invention is applied to a display device will be described as an example.

  The image signal input (or received) to the display device according to the embodiment of the present invention is a luminance signal transmitted from the image signal transmission device (hereinafter referred to as “input luminance signal”) and an image. It is a general term for color signals transmitted from a signal transmission device (hereinafter referred to as “input color signals”). Here, the image signal according to the embodiment of the present invention may indicate a still image or may be a moving image (so-called video). In addition, as described above, the input luminance signal may be a Y / C-separated luminance signal (pseudo HD resolution luminance signal) in the image signal transmission apparatus. Similarly, the input color signal may be a Y / C separated color signal (a pseudo HD resolution color signal) in the image signal transmission apparatus.

(Display device according to an embodiment of the present invention)
FIG. 2 is a block diagram illustrating a configuration example of the display device 100 according to the embodiment of the present invention. Referring to FIG. 2, the display device 100 includes a signal input unit 102, an image processing unit 104, and a display unit 106.

  The display device 100 includes, for example, a control unit (not shown) configured by an MPU (Micro Processing Unit) or the like that can control the entire display device 100, a program used by the control unit, an operation parameter, and the like. ROM (Read Only Memory; not shown) in which control data is recorded, RAM (Random Access Memory; not shown) that primarily stores programs executed by the control unit, video files, image files, applications, etc. You may provide the memory | storage part (not shown) which can memorize | store, the operation part (not shown) which a user can operate. The display device 100 connects the above-described constituent elements by, for example, a bus as a data transmission path. The control unit can also function as the image processing unit 104.

  Here, as the storage unit (not shown), for example, a magnetic recording medium such as a hard disk, an EEPROM (Electronically Erasable and Programmable Read Only Memory), a flash memory, a MRAM (Magnetoresistive Random Access) Non-volatile memory such as Memory (RAM), FeRAM (Ferroelectric Random Access Memory), PRAM (Phase change Random Access Memory), and the like, but is not limited thereto.

  Examples of the operation unit (not shown) include an operation input device such as a keyboard and a mouse, a rotary selector such as a button, a direction key, and a jog dial, or a combination thereof. I can't. Examples of the display unit 106 include an LCD (Liquid Crystal Display), an organic EL display (Organic Light Emitting Diode display), and the like. Not limited to.

[Hardware configuration example of display device 100]
FIG. 3 is an explanatory diagram illustrating an example of a hardware configuration of the display device 100 according to the embodiment of the present invention. Referring to FIG. 3, the display device 100 includes, for example, an MPU 120, a ROM 122, a RAM 124, a recording medium 126, an input / output interface 128, an operation input device 130, a display device 132, and a communication interface 134. . In addition, the display device 100 connects each component with a bus 136 as a data transmission path, for example.

  The MPU 120 functions as a control unit that controls the entire display device 100. The MPU 120 can also serve as the image processing unit 104 in the display device 100.

  The ROM 122 stores programs used by the MPU 120 and control data such as calculation parameters, and the RAM 124 primarily stores programs executed by the MPU 120.

  The recording medium 126 functions as a storage unit of the display device 100 and can store video files, image files, applications, and the like. Here, examples of the recording medium 126 include a magnetic recording medium such as a hard disk and a non-volatile memory such as a flash memory, but are not limited thereto.

  The input / output interface 128 connects, for example, the operation input device 130 and the display device 132. Here, examples of the input / output interface 128 include a USB (Universal Serial Bus) terminal, a DVI (Digital Visual Interface) terminal, an HDMI (High-Definition Multimedia Interface) terminal, and the like, but are not limited thereto. The operation input device 130 is provided on the display device 100 such as buttons, direction keys, a rotary selector such as a jog dial, or a combination thereof, and is connected to the input / output interface 128 inside the display device 100. The The display device 132 is provided on the display device 100 such as an LCD or an organic EL display, and is connected to the input / output interface 128 inside the display device 100. Needless to say, the input / output interface 128 can be connected to an operation input device (for example, a keyboard or a mouse) as an external device of the display device 100 or a display device (for example, an external display).

  The communication interface 134 is an interface for performing wired / wireless communication with an external device, and functions as the signal input unit 102. Here, examples of the communication interface 134 include an IEEE 802.11 port, an RF (Radio Frequency) circuit, an HDMI terminal, and the like, but are not limited thereto.

  The display device 100 detects the up-converted cross color interference related to Y / C separation based on the input image signal with a hardware configuration as shown in FIG. In addition, the display device 100 can reduce the cross-color interference (noise) up-converted based on the detection result of the cross-color interference and improve the image quality with the hardware configuration shown in FIG. The hardware configuration of the display device according to the embodiment of the present invention is not limited to FIG. For example, the display device according to the embodiment of the present invention may further include an image processing circuit that realizes a function of the image processing unit 104 described later.

  With reference to FIG. 2 again, each component of the display device 100 will be described. The signal input unit 102 serves to receive an image signal transmitted by wire / wireless from the broadcasting station 10 or the image reproducing devices 20, 30,... And decode the received image signal.

  The image processing unit 104 performs various image processing on the image signal received by the signal input unit 102. Image processing performed by the image processing unit 104 includes, for example, IP (Interlace / Progressive) conversion processing for converting an interlace signal into a progressive signal, chroma processing for performing color-related processing such as color space change, and generation of an intermediate frame. Intermediate frame generation processing to increase the frame rate, cross-color interference detection processing to detect up-converted cross-color interference, cross-color interference reduction processing to reduce up-converted cross-color interference (noise), etc. It is not limited to the above. Cross color interference detection processing and cross color interference reduction processing according to an embodiment of the present invention will be described later.

  The display unit 106 displays an image corresponding to the image signal based on the image signal processed by the image processing unit 104. The display unit 106 can also display the detection result of cross color interference in the image processing unit 104.

[Configuration Example of Display Unit 106]
The display unit 106 includes a panel 110, a row driving unit 112, a column driving unit 114, a power supply unit 116, and a display control unit 118.

  The panel 110 includes a plurality of pixels arranged in a matrix (matrix), and serves as a display screen on which an image is displayed. For example, a panel for displaying an SD resolution image has at least 640 × 480 = 307200 (data lines × scanning lines) pixels, and the pixels are R, G, B subpixels for color display. ) × 640 × 480 × 3 = 921600 (data lines × scanning lines × number of subpixels). Similarly, for example, a panel that displays an HD resolution video has 1920 × 1080 pixels, and in the case of color display, has 1920 × 1080 × 3 subpixels.

  Further, the panel 110 may include, for example, a pixel circuit (not shown) for controlling the amount of voltage / current applied to each pixel. The pixel circuit includes, for example, a switch element and a drive element for controlling the amount of current by an applied scanning signal and a voltage signal, and a capacitor for holding a voltage signal. The switch element and the drive element are composed of, for example, a thin film transistor.

  For example, the row driving unit 112 and the column driving unit 114 apply voltage signals to a plurality of pixels included in the panel 110 to cause each pixel to emit light. Here, one of the row driving unit 112 and the column driving unit 114 applies a voltage signal (scanning signal) that determines ON / OFF of a pixel, and the other applies a voltage signal (image signal) corresponding to an image to be displayed. It can play the role of applying.

  Further, as a driving method of the row driving unit 112 and the column driving unit 114, for example, a dot-sequential driving scanning method in which light is emitted for each pixel arranged in the matrix form, and the pixels arranged in the matrix form are arranged for each column. Examples include a line sequential drive scanning method for emitting light, and a surface sequential drive scanning method for emitting light from all the pixels arranged in the matrix. The display unit 106 of the display device 100 illustrated in FIG. 2 includes two drive units, that is, the row drive unit 112 and the column drive unit 114. However, the display device according to the embodiment of the present invention includes the display unit. Needless to say, it can be configured by one drive unit.

  The power supply unit 116 supplies power to the row driving unit 112 and the column driving unit 114, and a voltage is applied to the row driving unit 112 and the column driving unit 114. The magnitude of the voltage that the power supply unit 116 applies to the row driving unit 112 and the column driving unit 114 varies according to the image signal processed by the image processing unit 104.

  The display control unit 118 is configured by, for example, an MPU and the like, and in accordance with the image signal processed by the image processing unit 104, a voltage for determining ON / OFF of the pixel is applied to one of the row driving unit 112 and the column driving unit 114 A control signal to be applied to is input, and an image signal is input to the other. The display control unit 118 can also control the supply of power to the row driving unit 112 and the column driving unit 114 by the power supply unit 116 in accordance with the image signal processed by the image processing unit 104.

  The display device 100 has a configuration as shown in FIG. 2 and can detect cross-color interference that has been up-converted based on an input image signal. Further, the display device 100 reduces the up-converted cross color interference (noise) related to the Y / C separation based on the detection result of the cross color interference, and displays the image with the reduced cross color interference on the display screen. Can be displayed.

[Image Processing in Image Processing Unit 104 According to the Embodiment of the Present Invention]
Next, the image processing in the image processing unit 104 of the display device 100 will be described more specifically. Hereinafter, as image processing according to the embodiment of the present invention, [1] cross-color interference detection processing and [2] cross-color interference reduction processing using the cross-color interference detection processing will be described.

  Here, the cross-color interference to be detected by the image processing unit 104 is, for example, a pseudo HD resolution image signal transmitted from an image signal supply source such as the broadcast station 10 or the image reproducing devices 20, 30,. Means "up-converted cross-color interference". Further, “up-converted cross color interference” is noise generated when a luminance signal component is mixed in an input color signal, and appears, for example, as rainbow pattern noise (colored moire) on an image.

[1] Cross Color Interference Detection Processing in Image Processing Unit 104 First, the cross color interference detection processing in the image processing unit 104 of the display device 100 will be described more specifically.

(1-1) Upconverted Cross Color Interference Detection Approach First, an upconverted cross color interference detection approach according to an embodiment of the present invention will be described.

(1-1-A) Overview of Detection Approach As described above, when the image signal processed by the image processing unit 104 is a pseudo HD resolution image signal, the cross color interference component is inverted for each line. The characteristics of the image signal related to the occurrence of the cross color interference change from the image signal of the SD resolution, such as loss of the color or the spatial frequency of the cross color interference component changing. Therefore, when processing a pseudo HD resolution image signal, for example, it was effective for an analog broadcast image signal “detection of a cross color interference component utilizing the property that the cross color interference component is inverted for each line. Even if a method (for example, a method of filtering in the vertical direction) is used, the up-converted cross-color interference cannot be detected. Similarly, when processing a pseudo HD resolution image signal, a “detection method for detecting cross-color interference based on a predetermined spatial frequency component (for example, a method using a bandpass filter)” or the like is used. If so, the up-converted cross-color interference cannot be detected.

  Further, when the image signal processed by the image processing unit 104 is a pseudo HD resolution image signal, the up-converted cross-color interference component has a characteristic of taking various hues according to the space / time axis coordinates. Have. Therefore, for example, when attention is paid to a certain pixel (hereinafter, the pixel of interest is referred to as a “pixel of interest”), the current frame (hereinafter referred to as “current frame”) of the pixel of interest and the previous frame from the current frame. There is a possibility that the difference value between this frame (hereinafter referred to as the “previous frame”) varies greatly. Therefore, for example, even if a difference value between the current frame and the previous frame is derived for each pixel, it is not always possible to detect cross-color interference that has been up-converted based on the difference value.

  Therefore, the image processing unit 104 recognizes the input color signal as a color vector, and detects cross-color interference that has been up-converted using a color vector declination difference between frames (hereinafter referred to as “declination difference”). Plan. Here, when an up-converted cross-color interference has occurred in the pseudo HD resolution image signal, the color vector declination difference takes a value of a certain size regardless of the space / time axis coordinates. Has the nature of continuing. For example, when the input image signal indicates a still image, the deviation angle difference between the current frame and the previous frame takes a value close to 180 °. Even when the input image signal represents a moving image, the declination difference has a value of a certain level or more. The above property is the same as when cross-color interference occurs in an SD resolution image signal, and does not change before and after up-conversion.

  Therefore, the image processing unit 104 can detect the up-converted cross-color interference that cannot be detected by the conventional detection method by performing the detection process based on the color vector declination difference between frames as described above. it can.

Hereinafter, the up-converted cross color interference detection method based on the color vector deviation difference according to the embodiment of the present invention will be described more specifically. In the following, as an input color signal input to the image processing unit 104, a blue color difference signal (hereinafter sometimes referred to as “U signal”) that can represent a color vector as a two-dimensional vector, and A case where a red color difference signal (hereinafter sometimes referred to as “V signal”) is input will be described as an example. Note that the input color signal according to the embodiment of the present invention is not limited to a color difference signal whose color space is represented by YUV, and may be signals of various color spaces such as YPbPr and L ^* a ^* b ^*. it can.

(1-1-B) Cross Color Interference Detection Method Based on Color Vector Deflection Difference FIG. 4 shows an upconverted cross color interference detection method based on a color vector declination difference according to an embodiment of the present invention. It is explanatory drawing for demonstrating. Here, FIG. 4 is a diagram illustrating the input color signal by the u axis corresponding to the U signal and the v axis corresponding to the V signal. Hereinafter, an up-converted cross color interference detection method based on a color vector deviation difference according to an embodiment of the present invention will be described with reference to FIG.

[First detection method]
Assuming that the value of the input color signal of the current frame in the pixel of interest is U signal = u1 and V signal = v1, the color vector (hereinafter referred to as “first color vector”) C1 in the current frame is “C1 = (u1, v1) ". Also, assuming that the value of the input color signal of the previous frame at the target pixel is U signal = u0 and V signal = v0, the color vector (hereinafter referred to as “second color vector”) C0 in the previous frame is “C0 = ( u0, v0) ".

  Here, if the angle formed by the first color vector C1 and the second color vector C0 is “θ”, the θ corresponds to the declination difference. That is, if θ is derived from the first color vector C1 and the second color vector C0, the image processing unit 104 performs up-conversion by setting the derived θ as an evaluation value that defines the degree of occurrence of cross-color interference. Cross color interference can be detected.

[Second detection method]
As shown in the first detection method, by deriving θ shown in FIG. 4, the image processing unit 104 can detect cross-color interference that has been up-converted based on the derived θ. However, in order to directly derive θ from the first color vector C1 and the second color vector C0, a complicated arithmetic operation is required. Therefore, in order to directly derive θ from the first color vector C1 and the second color vector C0, the image processing unit 104 may have to include a large-scale arithmetic processing circuit, for example.

  Therefore, as a second detection method, the image processing unit 104 does not derive θ from the first color vector C1 and the second color vector C0, but from the first color vector C1 and the second color vector C0, “ cos θ ”is derived. As is apparent from the fact that cos θ derived in the second detection method includes θ indicating the deviation angle difference of the color vector, it is information on the deviation angle difference of the color vector. The image processing unit 104 detects the up-converted cross color interference by using the derived cos θ as an evaluation value that defines the degree of occurrence of the cross color interference.

  Here, the cos θ derived in the second detection method is less likely to cause cross-color interference as the cos θ value is closer to “1.0”, and conversely, the cos θ value is smaller. It can be said that the closer to “−1.0”, the higher the possibility of cross-color interference. Therefore, the image processing unit 104 can detect the up-converted cross color interference by deriving cos θ.

  Hereinafter, a method for deriving cos θ according to the second detection method will be described. The image processing unit 104 uses the absolute value of the first color vector C1, the absolute value of the second color vector C0, and the inner product (inner product value) of the first color vector C1 and the second color vector C0. Deriving cos θ. Here, the absolute value of the first color vector C1 is derived by the following Equation 1, and the absolute value of the second color vector C0 is derived by the following Equation 2. Further, the inner product of the first color vector C1 and the second color vector C0 is derived by the following Equation 3. Therefore, from Equations 1 to 3, cos θ is derived by Equation 4 below.

  As shown in FIG. 4, when the first color vector C1 and the second color vector C0 are represented on the UV plane, the values of u0, u1, v0, and v1 have positive and negative values, respectively. . For example, when the input color signal is represented by 8 bits, the U signal and the V signal each have a value of “−128 to 127”. Here, when the input color signal has only a positive value such as an offset binary, for example, the image processing unit 104 performs, for example, a color before performing the arithmetic processing shown in the following Equations 1 to 4. The values of the first color vector C1 and the second color vector C0 may be converted by space conversion or the like.

・・・（数式１）

... (Formula 1)

・・・（数式２）

... (Formula 2)

・・・（数式３）

... (Formula 3)

・・・（数式４）

... (Formula 4)

  The image processing unit 104 using the second detection method derives cos θ from Equations 1 to 4 above. Here, the derived cos θ is information on the declination difference of the color vector, as is clear from the fact that θ indicates the declination difference of the color vector. Therefore, the image processing unit 104 detects the up-converted cross-color interference by setting the derived cos θ as an evaluation value that defines the degree of occurrence of cross-color interference, as in the case where θ is the evaluation value. Can do.

[Modification 1 of Second Detection Method]
As shown in the second detection method, by deriving cos θ, it is possible to detect the up-converted cross color interference while reducing the circuit scale related to detection of the cross color interference, for example. However, since Equation 4 includes a square root, the image processing unit 104 using the second detection method must include an arithmetic processing circuit having a larger scale than an arithmetic circuit that processes natural numbers in order to derive cos θ. There is.

  Therefore, the image processing unit 104 simplifies the calculation of the square root and reduces the circuit scale by using, for example, a look-up table in which the square root and discrete values are associated. By using the lookup table as described above, the calculation of the square root shown in Equation 4 is not necessary, so that the image processing unit 104 is realized with a simpler configuration.

[Second Modification of Second Detection Method]
Further, the method of realizing the image processing unit 104 with a simpler configuration is not limited to the method using a lookup table. For example, the image processing unit 104 can derive “cos ² θ” instead of cos θ as shown in the following Equation 5, and set cos ² θ as an evaluation value that defines the degree of occurrence of cross-color interference. Here, the derived cos ² θ is information on the declination difference of the color vector, as is clear from the fact that θ indicates the declination difference of the color vector. Therefore, the image processing unit 104 detects the up-converted cross color interference by using the derived cos ² θ as an evaluation value that defines the degree of occurrence of cross color interference, as in the case where θ is the evaluation value. can do. Note that “sgn (C0 · C1)” shown in Equation 5 indicates the sign portion of the inner product of the first color vector C1 and the second color vector C0.

・・・（数式５）

... (Formula 5)

[Variation 3 of the second detection method]
In the above, “cos θ” and “cos ² θ” are given as the evaluation values that define the degree of occurrence of cross-color interference according to the second detection method, but the evaluation values are not limited to the above. For example, by using a look-up table in which the values of “cos θ” and “cos ² θ” and the value of “θ” are associated, the image processing unit 104 using the second detection method performs “θ”. May be an evaluation value that defines the degree of occurrence of cross-color interference.

  The image processing unit 104 derives an evaluation value that defines the degree of occurrence of cross-color interference by using the first detection method or the second detection method described above (or a modified example related to the second detection method). be able to.

Here, evaluation values such as “cos θ” and “cos ² θ” derived by the image processing unit 104 as the degree of occurrence of cross-color interference are information on the declination difference of the color vector. As described above, the declination difference of the color vector is the spatial / temporal when the up-converted cross-color interference occurs in the pseudo HD resolution image signal up-converted from the SD resolution image signal. It has the property of taking a certain amount of value regardless of the axis coordinates. Therefore, the display device 100 determines, for example, whether up-converted cross-color interference has occurred or not, and whether the up-converted cross-color interference has occurred, depending on the degree of occurrence of the cross-color interference derived by the image processing unit 104. It can be recognized for each pixel whether or not a certain degree has occurred. That is, deriving the degree of occurrence of cross-color interference by the image processing unit 104 is equivalent to determining (or detecting) the occurrence of up-converted cross-color interference for each pixel.

  Therefore, the image processing unit 104 can detect the up-converted cross color interference by deriving the degree of occurrence of the cross color interference.

  In the above description, the case where the first color vector C1 and the second color vector C0 are represented by two-dimensional vectors has been described as an example. However, the present invention is not limited thereto. For example, the image processing unit according to the embodiment of the present invention can also derive information on the color vector declination difference based on a color vector as a three-dimensional vector.

(1-2) Flow of detection process of up-converted cross-color interference Next, a flow of detection process of up-converted cross-color interference according to the embodiment of the present invention using the above-described detection approach will be described. . In the following, the up-converted cross color interference detection process in the case of using the above-described second detection method (or a modification of the second detection method) will be described.

  For example, the image processing unit 104 detects the up-converted cross color interference for each pixel by the following processes [1-2A] to [1-2-D].

[1-2-A] Derivation of Color Vector The image processing unit 104 derives the first color vector C1 for each pixel based on the input color signal. Here, for example, when the color space of the input color signal is a color space represented by three (or three or more) color components, the image processing unit 104 converts the color space into two color components. After the conversion to the color space represented by the two, the first color vector C1 is derived for each pixel. As described above, by selectively performing color space conversion according to the color space of the input color signal, the image processing unit 104 can handle the color vector as a two-dimensional vector as shown in FIG. it can. Therefore, even when the input color signal is a color space represented by three (or three or more) color components, the image processing unit 104 uses the second detection method described above to perform cross color. An evaluation value that defines the degree of occurrence of interference can be derived. Needless to say, the image processing unit according to the embodiment of the present invention can derive the degree of occurrence of cross-color interference based on the information on the angle difference of the color vector, for example, based on the color vector as a three-dimensional vector. .

[1-2B] Holding Color Vector The image processing unit 104 holds the derived first color vector C1 for each pixel. By holding the first color vector C1 for each pixel, the image processing unit 104 can use the held color vector as the second color vector (color vector corresponding to the previous frame).

Derivation of [1-2-C] color vector inner product The image processing unit 104 holds the first color vector C1 derived in [1-2-A] and [1-2-B]. Based on the second color vector C0, an inner product of the color vectors is derived.

[1-2D] Derivation of degree of occurrence of cross-color interference The image processing unit 104 holds the first color vector C1 derived in [1-2A] and [1-2-B]. The degree of occurrence of cross-color interference is derived based on the inner product of the second color vector C0 and the color vector derived in [1-2-C]. Here, the image processing unit 104 can derive the degree of occurrence of cross-color interference by performing the calculation of Equation 4, but is not limited thereto. For example, the image processing unit 104 can simplify the calculation by using a look-up table or the like, or can derive the degree of occurrence of cross-color interference by performing the calculation of Equation 5.

“Cos θ”, “cos ² θ”, and the like derived as the degree of occurrence of cross-color interference by the image processing unit 104 are information on the color vector declination difference. As described above, the declination difference of the color vector is the spatial / temporal when the up-converted cross-color interference occurs in the pseudo HD resolution image signal up-converted from the SD resolution image signal. It has the property of taking a certain amount of value regardless of the axis coordinates. Therefore, the image processing unit 104 can detect the up-converted cross color interference by deriving the degree of occurrence of the cross color interference. Hereinafter, a configuration related to the detection process of the up-converted cross color interference in the image processing unit 104 will be described.

(1-3) Configuration Related to Cross Color Interference Detection Processing in Image Processing Unit 104 FIG. 5 is a configuration example related to cross color interference detection processing upconverted in the image processing unit 104 according to the embodiment of the present invention. FIG. Here, the image processing unit 104 can perform image processing with hardware (for example, an image processing circuit) and / or software (image processing software).

Hereinafter, a case where a U signal and a V signal are input as input color signals input to the image processing unit 104 will be described as an example. Note that the input color signal according to the embodiment of the present invention is not limited to the color difference signal whose color space is represented by YUV. For example, the color space is represented by two color components such as YIQ and L ^* a ^* b ^*. Various color spaces can be used, such as a signal of a color space represented by three color components such as RGB and CMY.

  Here, when the input color signal is a signal in a color space represented by three color components, the image processing unit according to the embodiment of the present invention, for example, of the color vector deriving unit 150 shown in FIG. A color space conversion unit (not shown) can be further provided in the previous stage. A color space conversion unit (not shown) plays a role of selectively converting into a color space represented by two color components in accordance with an input color signal. Note that the image processing unit according to the embodiment of the present invention uses the color space signal represented by three color components as they are (that is, by a three-dimensional color vector), and thereby relates to the declination difference of the color vector. Needless to say, the degree of occurrence of cross-color interference can be derived.

  Referring to FIG. 5, the image processing unit 104 includes a color vector deriving unit 150, a color vector holding unit 152, an inner product deriving unit 154, and a cross color interference determining unit 156.

  The color vector deriving unit 150 plays the role of performing the process [1-2A], and derives the first color vector C1 for each pixel based on the input color signal (U signal, V signal). Further, the color vector deriving unit 150 transmits the derived first color vector C1 to the color vector holding unit 152, the inner product deriving unit 154, and the cross color interference determining unit 156.

  The color vector holding unit 152 plays the role of performing the above [1-2B], and holds the first color vector C1 transmitted from the color vector deriving unit 150 for each pixel. Here, the color vector holding unit 152 may be configured to hold, for example, the current frame color vector (first color vector C1) and the previous frame color vector (second color vector C0). It is not limited to the above. For example, the color vector holding unit 152 can hold a color vector corresponding to an arbitrary number of frames for each pixel. Further, the color vector holding unit 152 can be configured by a frame memory, for example, but is not limited thereto.

  Further, the color vector holding unit 152 derives the inner product of the held second color vector C0 in accordance with, for example, a read command from the MPU or a reference clock signal transmitted from an oscillator (not shown) or the like. To the unit 154 and the cross color interference determination unit 156.

  The inner product deriving unit 154 plays the role of performing the process of [1-2C], and the first color vector C1 transmitted from the color vector deriving unit 150 and the second color transmitted from the color vector holding unit 152. An inner product of color vectors is derived based on the vector C0. Then, the inner product deriving unit 154 transmits the inner product of the derived color vectors to the cross color interference determining unit 156.

  The cross-color interference determining unit 156 serves to perform the above [1-2-D] process. The cross color interference determination unit 156 includes the first color vector C1 transmitted from the color vector deriving unit 150, the second color vector C0 transmitted from the color vector holding unit 152, and the color vector transmitted from the inner product deriving unit 154. The degree of occurrence of cross color interference is derived based on the inner product. Then, the cross color interference determination unit 156 outputs the derived degree of occurrence of the cross color interference. Here, the display device 100 performs, for example, a cross color reduction process described later using the degree of occurrence of cross color interference output from the cross color interference determination unit 156, but is not limited thereto.

For example, with the configuration illustrated in FIG. 5, the image processing unit 104 derives the degree of occurrence of cross-color interference related to the declination difference of color vectors such as “cos θ” and “cos ² θ” based on the input color signal. can do. As described above, the declination difference of the color vector is the spatial / temporal when the up-converted cross-color interference occurs in the pseudo HD resolution image signal up-converted from the SD resolution image signal. It has the property of taking a certain amount of value regardless of the axis coordinates. Therefore, the image processing unit 104 derives the degree of occurrence of cross color interference related to the color vector deviation difference based on the input image signal, thereby performing the up-converted cross color interference related to Y / C separation. Can be detected.

(1-4) First image processing method according to an embodiment of the present invention (up-converted cross color interference detection method)
Next, the first image processing method according to the embodiment of the present invention will be described. FIG. 6 is a flowchart showing an example of the first image processing method according to the embodiment of the present invention, and shows an example of the detection method of the up-converted cross color interference. In the following description, the first image processing method is described as being performed by the display device 100. However, as described above, the image processing device according to the embodiment of the present invention can also be performed.

  The display device 100 derives a first color vector corresponding to the current frame for each pixel based on the input color signal (for example, U signal, V signal) (S100). Then, the display device 100 holds the first color vector derived in step S100 (S102). Here, the first color vector held in step S102 is the second color vector corresponding to the previous frame when the input color signal of the next frame is input (when the current frame transitions).

  The display device 100 derives the inner product of the color vectors for each pixel based on the first color vector derived in step S100 and the second color vector held in step S102 (S104).

  The display device 100 determines the degree of occurrence of cross-color interference based on the inner product of the first color vector derived in step S100, the second color vector held in step S102, and the color vector derived in step S104. (S106; detection of up-converted cross-color interference).

  By using the first image processing method shown in FIG. 6, the display device 100 can perform the processes [1-2A] to [1-2D] described above. Therefore, the display device 100 using the first image processing method shown in FIG. 6 can detect the up-converted cross color interference related to Y / C separation based on the input image signal.

[2] Cross Color Interference Reduction Processing in Image Processing Unit 104 When the image processing unit 104 performs the above-described process [1] (cross color interference detection processing), the display device 100 is improved in Y / C separation. Converted cross-color interference can be detected. Therefore, next, a cross color interference reduction process using a cross color interference detection process will be described as the image processing according to the embodiment of the present invention.

(2-1) Upconverted Cross Color Interference Reduction Approach First, an upconverted cross color interference reduction approach according to an embodiment of the present invention will be described.

  When the image signal processed by the image processing unit 104 is a pseudo HD resolution image signal, as described above, the property that the cross color interference component is inverted for each line is lost, or the space of the cross color interference component is lost. The nature of the image signal related to the occurrence of cross-color interference, such as a frequency change, changes from an SD resolution image signal. Therefore, when processing a pseudo HD resolution image signal, for example, it is effective for an analog broadcast image signal, “a cross color interference component utilizing the property that the cross color interference component is inverted for each line. A reduction method (for example, a method for filtering in the vertical direction) or a “reduction method for detecting and reducing cross-color interference based on a predetermined spatial frequency component (for example, a method using a bandpass filter)” However, cross-color interference cannot be reduced.

  Therefore, the image processing unit 104 focuses on the property that the cross color interference component is inverted every other frame, not the property that the cross color interference component is inverted every line. Here, the property that the cross color interference component is inverted every other frame is not lost even in the pseudo HD resolution image signal obtained by up-converting the SD resolution image signal. Therefore, the cross color interference component can be effectively reduced by utilizing the property that the cross color interference component is inverted every other frame.

  However, when the image processing unit 104 performs the cross-color interference reduction process even for pixels where cross-color interference has not occurred, for example, the image is generated due to the cross-color interference reduction process. Side effects such as blurring may occur. For this reason, the image processing unit 104 detects the pixel in which the cross-color interference is up-converted using the above-described process [1] (cross-color interference detection process) or the like, and selectively selects the pixel based on the detection result. To reduce cross color interference. Therefore, the image processing unit 104 can perform the cross color interference reduction process only on the pixels in which the up-converted cross color interference occurs, so that the cross color is prevented while preventing side effects such as blurring of the image. Interfering components can be effectively reduced.

  Hereinafter, an approach for reducing the up-converted cross color interference in the image processing unit 104 will be described in detail. The image processing unit 104 uses the property that the cross color interference component is inverted every other frame, and is up-converted by, for example, the following processes [2-1-A] to [2-1-E]. Cross color interference is reduced pixel by pixel. Hereinafter, a case where a U signal and a V signal are input as input color signals input to the image processing unit 104 will be described as an example. Needless to say, the input color signal according to the embodiment of the present invention is not limited to the color difference signal whose color space is represented by YUV.

[2-1-A] Smoothing of input color signal in time axis direction The image processing unit 104 uses, for example, a smoothing filter in the time axis direction to perform U signal and V signal (input color signal). Smoothing in the time axis direction is performed for each pixel.

  Here, examples of the smoothing filter in the time axis direction include, but are not limited to, a 2-tap low-pass filter (Low-Pass Filter; that is, a configuration for deriving an average value from the previous frame). For example, the smoothing filter in the time axis direction is not limited to a 2-tap low-pass filter, and the number of taps can be set arbitrarily. The smoothing filter in the time axis direction is not limited to a low-pass filter, and various filters such as a moving average filter and a weighted average filter can be used. Further, the smoothing filter in the time axis direction is not limited to the FIR (Finite Impulse Response Filter) filter (non-recursive filter) as described above, and an IIR (Infinite Impulse Response) filter (cyclic filter) is used. Also good. By using the IIR filter, a filter having a long tap number can be realized by using a frame memory corresponding to one screen.

  In addition, the filter coefficient of the smoothing filter can be set so that, for example, the sum of odd-numbered coefficients and the sum of even-numbered coefficients when the image indicated by the image signal represents a still image are equal. . By setting as described above, the image processing unit 104 can theoretically set the cross color interference component to 0 (zero) by smoothing.

  By using the smoothing filter as described above, the image processing unit 104 performs input color signal smoothing in the time axis direction for each pixel (hereinafter, referred to as “smoothed color signal” in some cases). Can be obtained.

[2-1-B] Suppression of gain of smoothed color signal When an input image signal includes up-converted cross color interference, the U signal and the V signal may have an abnormally large value. Many. In addition, the above-described feature is one of the factors that make cross-color interference conspicuous when an image corresponding to an image signal that includes up-converted cross-color interference is displayed on the display screen. Therefore, the image processing unit 104 multiplies the smoothed color signal by a gain of 1.0 or less (gain suppression value, hereinafter referred to as “suppression gain” in some cases) for each pixel. The gain of the color signal is suppressed. By suppressing the gain of the smoothed color signal, the influence of the up-converted cross color interference can be reduced.

  FIG. 7 is an explanatory diagram illustrating an example of suppression of the gain of the smoothed color signal according to the embodiment of the present invention. Here, FIG. 7 shows an example in which a U signal and a V signal (U, V input) are taken on the x axis, and a smoothed color signal (U, V output) is taken on the y axis.

<2-1-B-1> When U signal and V signal are smaller than threshold th (section p in FIG. 7)
When the U signal and the V signal are smaller than the threshold th2, the image processing unit 104 does not suppress the gain of the smoothed color signal. That is, as shown in FIG. 7, the relationship “y = x” is established in the section p.

  Here, the smaller the threshold th value, the easier the smoothing color signal gain suppression process works. Conversely, the larger the threshold th value, the harder the smoothed color signal gain suppression process works. . That is, by setting the threshold th for the smoothing color signal gain suppression process, the image processing unit 104 can adjust the workability of the smoothing color signal gain suppression process. Further, the value of the threshold th can be adjusted, for example, by a user operating an operation unit (not shown), but is not limited thereto.

<2-1-B-2> When U signal and V signal are greater than or equal to threshold th (section q in FIG. 7)
When the U signal and the V signal are equal to or greater than the threshold th, the image processing unit 104 suppresses the gain of the smoothed color signal using, for example, the following formulas 6 and 7. Here, Formula 6 shows the suppression gain. That is, by using Expressions 6 and 7, the image processing unit 104 can suppress the gain of the smoothed color signal as the values of the U signal and the V signal are larger.

G = 1.0 + (g0−1.0) × (X / L)
... (Formula 6)

Y = G × X
... (Formula 7)

  In the above description, the example in which the image processing unit 104 suppresses the gain of the smoothed color signal using Expression 6 and Expression 7 is described, but the present invention is not limited thereto. For example, the image processing unit 104 can suppress the gain of the smoothed color signal by multiplying each of the U signal and the V signal by a preset suppression gain.

  In the above description, the example in which the image processing unit 104 suppresses the gain independently of the U signal and the V signal has been described. However, the present invention is not limited thereto. Here, when the gain is suppressed independently for the U signal and the V signal, the hue may change. Therefore, for example, the image processing unit 104 can also suppress the gain with respect to the U signal and the V signal so that a hue change due to the gain suppression does not occur.

  More specifically, for example, the image processing unit 104 first compares the absolute value of the U signal and the absolute value of the V signal for each pixel. Next, the image processing unit 104 derives a suppression gain using a value having a large absolute value for each pixel and Equation 6 based on the comparison result. Then, the image processing unit 104 multiplies the U signal and the V signal by the derived suppression gain. That is, each of the U signal and the V signal is multiplied by a suppression gain having the same value. By performing the gain suppression in the above procedure, the image processing unit 104 can suppress the gain for the U signal and the V signal while preventing the hue from changing.

  In the above, the example of preventing the change in hue using the maximum values of the U signal and the V signal has been described. However, the method for preventing the change in hue according to the embodiment of the present invention is not limited to the above. For example, the image processing unit 104 can also perform gain suppression by deriving the suppression gain using other values such as the added value of the U signal and the V signal and the magnitude of the UV vector.

  In the above, the example in which the image processing unit 104 prevents the hue change in the YUV space has been described. However, the method for preventing the hue change according to the embodiment of the present invention is not limited to the above. For example, the image processing unit 104 can convert the input color signal into another color space such as an HSV space, and can perform a process for preventing the hue change as described above in the converted color space.

[2-1-C] Detection of pixels in which cross-color interference has occurred In the above [2-1-A], it has been shown that a smoothed color signal is obtained. This is a process of degrading the signal in a sense. For this reason, when the noise-reduced input color signal output from the image processing unit 104 is a signal that has been smoothed down to pixels where cross-color interference has not occurred, side effects such as image blurring. May occur. Therefore, the image processing unit 104 detects pixels in which cross-color interference has occurred based on the input image signal (input luminance signal / input color signal) in order to prevent the above side effects.

  Here, the image processing unit 104 detects pixels in which cross-color interference has occurred, for example, by processing shown in the following [I] or a combination of the following [I] to [III].

[I] Detection of Pixels with Cross Color Interference Based on U Signal and V Signal The image processing unit 104 detects pixels with cross color interference based on the U signal and V signal (input color signal). To detect. Here, the image processing unit 104 can detect the up-converted cross color interference for each pixel by performing the above-described process [1] (cross color interference detection processing).

[II] Motion Detection The above [I] indicates that the pixel having the up-converted cross color interference is detected by performing the above-described processing [1] (cross color interference detection processing). It was. In other words, the image processing unit 104 detects the pixel where the up-converted cross color interference occurs by deriving the degree of occurrence of the cross color interference based on the information of the deviation angle difference of the color vector. Here, as described above, even when the input image signal includes cross-color interference obtained by up-conversion and represents a moving image, the color vector declination difference does not depend on the space / time axis coordinates. It takes a value larger than a certain level. Therefore, the image processing unit 104 can detect pixels in which up-converted cross-color interference has occurred even when the input image signal represents a moving image.

  However, in the above-described process [1] (cross color interference detection process), the up-converted cross color interference is detected after determining whether or not the input image signal is a moving image. is not. For this reason, when the input image signal represents a moving image, the image processing unit 104 may erroneously detect (not detect or over detect) a pixel in which cross color interference occurs. Here, if an erroneous detection occurs, there is a possibility that an undesirable result may occur, for example, the cross-color interference cannot be effectively reduced or the moving part is blurred. Therefore, the image processing unit 104 detects motion (motion amount) based on the correlation between the current frame and the previous frame, for example, and combines the result of the process [I] and the result of the motion detection process. . As a result, the image processing unit 104 can more reliably prevent erroneous detection of pixels in which cross-color interference occurs.

  Here, as a method of detecting motion, for example, a method of deriving a difference between the current frame and the previous frame for each pixel based on an input luminance signal (hereinafter also referred to as “Y signal”). Can be mentioned. For example, the image processing unit 104 calculates a difference value between the current frame and the previous frame for each pixel based on the Y signal value of a pixel belonging to a predetermined region including the target pixel (for example, a pixel around the target pixel). To derive. Then, the image processing unit 104 determines the degree of movement, for example, based on the total absolute value of the derived difference values. Here, for example, the image processing unit 104 can uniquely determine the degree of movement by using a lookup table in which the total value and a value indicating the degree of movement are associated with each other. Not limited.

  Further, the method for detecting the motion in the image processing unit 104 is not limited to the above. For example, the image processing unit 104 can detect a motion by deriving a motion vector and using the absolute value of the motion vector as a motion amount. Here, as a method for deriving a motion vector, for example, a method using template matching is cited, but the method is not limited to the above. Note that, for example, when a motion vector is derived in another process of the image processing unit 104 such as an IP conversion process or an intermediate frame generation process or another process performed by another component of the display device 100, the image The processing unit 104 can also use the motion vector. In the above case, motion can be detected more efficiently and with high accuracy.

[III] Detection of Pixels that Satisfy Cross-Color Interference Occurrence In [I] above, cross-color interference is generated based on the U signal and V signal using the property that the cross-color interference component is inverted every other frame. It was shown to detect pixels. Here, when cross-color interference occurs, the signal frequency may be characterized not only in the U signal and the V signal but also in the Y signal (input luminance signal). Therefore, the image processing unit 104 combines the result of the process [I] above with the detection result of the pixel that satisfies the condition for occurrence of cross-color interference based on the Y signal (the pixel that is highly likely to cause cross-color interference). As a result, the detection accuracy of the pixel in which the cross color interference occurs is further increased. Further, by combining the results of the above process [II], the image processing unit 104 can increase the detection accuracy of the pixel in which the cross color interference has occurred, and the erroneous detection of the pixel in which the cross color interference has occurred. Needless to say, this can be prevented more reliably.

  Here, as a method of detecting a pixel that satisfies the condition for generating the cross-color interference region, for example, a method based on the degree of the high frequency component of the Y signal can be mentioned. When cross-color interference occurs, there is a high possibility that a high frequency component is included in the diagonal direction of the Y signal. Therefore, the image processing unit 104 obtains a high-frequency component (detection value) from the Y signal by using, for example, a high-pass filter or a band-pass filter. Then, the image processing unit 104 derives, for each pixel, a degree that satisfies the condition for generating the cross-color interference region based on the detection value detected by filtering. Here, the degree of satisfying the condition for occurrence of the cross-color interference region is, for example, using a look-up table in which the number of detection values consecutive in the oblique direction is correlated with the degree of condition for satisfying the occurrence of the cross-color interference region. It can be derived, but is not limited to the above.

  For example, the image processing unit 104 can detect a pixel in which cross-color interference has occurred by the process shown in [I] or a process combining [I] to [III].

[2-1-D] Gain Value Setting The image processing unit 104 defines a ratio for mixing the input color signal and the smoothed color signal based on the detection result in [2-1-C]. Is set for each pixel. Here, for example, the gain value can be a value representing a ratio of mixing the smoothed color signal with the input color signal, but is not limited to the above, and represents a ratio of mixing the input color signal with the smoothed color signal. It may be a value.

  FIG. 8 is an explanatory diagram for explaining an example of a gain value setting method according to the embodiment of the present invention. Here, FIG. 8 shows an example when the gain value is a value representing the ratio of the smoothed color signal to the input color signal. FIG. 8 shows a case where the degree of occurrence of cross color interference is represented by “cos θ”. Hereinafter, a gain value setting method will be described with reference to FIG. 8 as appropriate.

<2-1-D-1> When using the detection result in the process [I] When using the detection result in the process [I] (that is, when using one detection result), the image processing unit 104 derives a gain value by, for example, the following Equation 8.

G1 = (th2-cos θ) × a (0.0 ≦ G ≦ 1.0)
... (Formula 8)

  “G1” in Expression 8 indicates a gain value, and “cos θ” indicates an example of a detection result in the process [i] such as the degree of occurrence of cross-color interference. Further, “th2” shown in Formula 8 indicates a threshold value at which the gain value starts to change from 0 (zero) as shown in FIG. Here, the smaller the threshold value th2, the more difficult the up-converted cross color interference reduction processing is. On the contrary, the larger the threshold value th2, the more the up-converted cross color interference reduction processing is performed. Easy to work. That is, by setting the threshold th2 for setting the gain value, the image processing unit 104 can adjust the workability of the up-converted cross color interference reduction process. Further, the value of the threshold th can be adjusted, for example, by a user operating an operation unit (not shown), but is not limited thereto.

  Further, “a” shown in Expression 8 represents the slope of the change in gain value as shown in FIG. Here, the smaller the value of the slope a, the slower the effect of the up-converted cross-color interference reduction process with respect to the change in the detection result in the process [I]. The larger the value is, the more abrupt the effect of the up-converted cross color interference reduction process is with respect to the change in the detection result in the process [I]. That is, by setting the slope a for setting the gain value, the image processing unit 104 can adjust the working method of the up-converted cross color interference reduction processing. Further, the value of the inclination a can be adjusted by, for example, the user operating an operation unit (not shown), but is not limited to the above.

  Although FIG. 8 shows an example in which the gain value is expressed by a linear line, it is not limited to the above. For example, the gain value according to the embodiment of the present invention is larger as “cos θ” (an example of the degree of occurrence of cross-color interference) is closer to “−1.0”, and closer to “1.0”. It may be arbitrarily set using a quadratic curve or the like as long as the condition that the smaller the distance is is satisfied.

<2-1-D-2> When using the detection results in the processes [I] to [III] in combination When using the detection results in the processes [I] to [III] in combination (that is, two In the case where the above detection result is used), the image processing unit 104 derives the gain value using, for example, Equation 9 and Equation 10 below. Here, Formula 9 shows a case where the detection results in the processes [I] to [III] are used in combination.

gN = (a0 × g0) + (a1 × g1) + (a2 × g2)
... (Formula 9)
G2 = (gN−th3) × a (0.0 ≦ G ≦ 1.0)
(Equation 10)

  “A0” shown in Equation 9 is a weighting coefficient for the detection result in the process [I]. “G0” indicates a value based on the detection result in the process [I], and corresponds to, for example, “G1” in Equation 8 above. “A1” shown in Equation 9 is a weighting coefficient for the detection result in the process [II], “g1” is a detection result in the process [II], and “a2” is a weighting coefficient for the detection result in the process [III]. “G2” indicates a detection result in the process [III]. As shown in Equation 9, the image processing unit 104 can derive the weighted detection result “gN” by weighting each detection result in the processes [I] to [III]. In addition, the image processing unit 104 can adjust which detection result is set as the gain value by setting the weighting coefficient for each detection result in the processes [I] to [III]. . The values of the weighting coefficients of the detection results in the processes [I] to [III] can be adjusted, for example, by the user operating an operation unit (not shown). I can't.

  Further, the image processing unit 104 derives a gain value by using “gN” derived in Equation 9 and Equation 10.

  Here, “th3” shown in Expression 10 indicates a threshold value at which the gain value starts to change from 0 (zero), similarly to “th2” in FIG. Here, the smaller the threshold value th3, the easier the up-converted cross-color interference reduction processing works. Conversely, the larger the threshold value th3, the greater the up-converted cross-color interference reduction processing. Hard to work. In other words, by setting the threshold th3 for setting the gain value, the image processing unit 104 can adjust the workability of the up-converted cross color interference reduction process. Further, the value of the threshold th3 can be adjusted by, for example, the user operating an operation unit (not shown), but is not limited thereto.

  By using the method shown in <2-1-D-1> or <2-1-D-2>, the image processing unit 104 detects the detection result in the process shown in [I] or [ A gain value can be set for each pixel based on a combination of detection results in the processes shown in [I] to [III].

  In addition, although the above formula 9 shows an example of deriving the detection results “gN” weighted using the detection results in the processes [I] to [III], that is, using the three detection results, Not limited to. For example, the image processing unit 104 detects the detection result in the process shown in [I] and the detection result in the process shown in [II], or the detection result in the process shown in [I] and the process shown in [III]. It is also possible to derive a weighted detection result “gN” using the two detection results, i.

[2-1-E] Mixing of input color signal and smoothed color signal based on gain value The image processing unit 104 performs pixel-by-pixel in accordance with the gain value set for each pixel in [2-1-D]. The input color signal and the smoothed color signal are mixed together. Specifically, the image processing unit 104, for example, “input color signal: smoothed color signal = (1-G): G based on the gain value“ G ”(for example, G1 or G2) for each pixel. The input color signal and the smoothed color signal are mixed so that " By the processing of [2-1-C] to [2-1-E], the image processing unit 104 can prevent the up-converted cross-color interference while more reliably preventing the occurrence of side effects such as blurring of the image. It can be reduced with high accuracy for each pixel.

  The image processing unit 104 reduces the up-converted cross color interference for each pixel by performing the processes [2-1-A] to [2-1-E] based on the input image signal. To do. Therefore, the display device 100 can display an image in which the up-converted cross-color interference is reduced for each pixel on the display screen, so that high image quality can be achieved. Hereinafter, a configuration related to the cross color interference reduction process in the image processing unit 104 will be described.

(2-2) Configuration Related to Cross Color Reduction Processing in Image Processing Unit 104 FIG. 9 is a block diagram showing an example of configuration related to cross color interference reduction processing in the image processing unit 104 according to the embodiment of the present invention. Here, the image processing unit 104 can perform image processing with hardware (for example, an image processing circuit) and / or software (image processing software).

  Hereinafter, a case where the Y signal, the U signal, and the V signal are input to the image processing unit 104 will be described as an example. In the following, the input color signal after noise reduction may be referred to as “U ′ signal” or “V ′ signal”. Needless to say, the input color signal according to the embodiment of the present invention is not limited to the color difference signal whose color space is represented by YUV.

  Referring to FIG. 9, the image processing unit 104 includes a three-dimensional filter 200 (filter), a gain suppression unit 202, a cross color interference detection unit 204, a motion detection unit 206, and a cross color interference occurrence condition detection unit 208. The gain setting unit 210 and the mixing unit 212 are provided. Here, the three-dimensional filter 200 serves to perform the process [2-1-A], and the gain suppression unit 202 serves to perform the process [2-1-B]. In addition, the cross color interference detection unit 204, the motion detection unit 206, and the cross color interference occurrence condition detection unit 208 serve to perform the above-described process [2-1-C]. The gain setting unit 210 serves to perform the above-described process [2-1-D], and the mixing unit 212 serves to perform the process [2-1-E].

  The three-dimensional filter 200 plays the role of performing the above [2-1-A], and smoothes the U signal and V signal in the time axis direction for each pixel. Here, the three-dimensional filter 200 can be configured with a 2-tap low-pass filter that performs smoothing in the time axis direction and the surface direction, but is not limited thereto.

  The gain suppression unit 202 serves to perform the above [2-1-B] process, and suppresses the gain for each pixel based on the smoothed color signal output from the three-dimensional filter 200.

  The cross color interference detection unit 204 serves to perform the process [I] of the processes [2-1-C], and a pixel in which cross color interference has occurred based on the U signal and the V signal. Is detected. Then, the cross color interference detection unit 204 transmits the degree of occurrence of cross color interference (detection result) to the gain setting unit 210 for each pixel. Here, the cross color interference detection unit 204 can derive the degree of occurrence of the cross color interference based on the information of the deviation angle difference of the color vector, for example, with a configuration as shown in FIG.

  The motion detection unit 206 serves to perform the process [II] of the processes [2-1-C], and detects a motion for each pixel based on the Y signal. Then, the motion detection unit 206 transmits a detection result such as the degree of motion, for example, to the gain setting unit 210 for each pixel.

  The cross color interference occurrence condition detection unit 208 plays a role of performing the process [III] of the processes [2-1-C], and a pixel that satisfies the conditions for the occurrence of the cross color interference area based on the Y signal. Is detected. Then, the cross color interference occurrence condition detection unit 208 transmits, for example, a detection result such as a degree satisfying the condition for generating the cross color interference region to the gain setting unit 210 for each pixel.

  The gain setting unit 210 plays the role of performing the process of [2-1-D], and the detection results transmitted from the cross color interference detection unit 204, the motion detection unit 206, and the cross color interference occurrence condition detection unit 208, respectively. Based on the above, a gain value is derived for each pixel. Then, the gain setting unit 210 transmits the gain value derived for each pixel to the mixing unit 212.

  The mixing unit 212 serves to perform the above-described processing [2-1-E]. Based on the gain value for each pixel transmitted from the gain setting unit 210, the mixing unit 212 performs an input color signal and a gain suppression unit for each pixel. The smoothed color signal with suppressed gain output from 202 is mixed. Then, the mixing unit 212 outputs the mixed color signal as a U ′ signal and a V ′ signal.

  For example, with the configuration shown in FIG. 9, the image processing unit 104 can reduce the up-converted cross-color interference for each pixel while more reliably preventing the occurrence of side effects such as blurring of the image.

  In the above description, the configuration in which the image processing unit 104 includes the cross color interference detection unit 204, the motion detection unit 206, and the cross color interference occurrence condition detection unit 208 has been described. However, the configuration is not limited thereto. For example, the image processing unit according to the embodiment of the present invention includes a configuration including only the cross color interference detection unit 204, a configuration including the cross color interference detection unit 204 and the motion detection unit 206, or a cross color interference detection unit 204 and A configuration including a cross color interference occurrence condition detection unit 208 may also be adopted. Even with the above configuration, the image processing unit according to the embodiment of the present invention can reduce the up-converted cross-color interference for each pixel.

(2-3) Second image processing method according to the embodiment of the present invention (up-converted cross color interference reduction method)
Next, a second image processing method according to the embodiment of the present invention will be described. FIG. 10 is a flowchart showing an example of the second image processing method according to the embodiment of the present invention, and shows an example of a method for reducing the up-converted cross color interference. In the following description, the second image processing method is described as being performed by the display device 100. However, as described above, the image processing device according to the embodiment of the present invention can also perform the second image processing method.

  The display apparatus 100 smoothes the U signal and the V signal (input color signal) in the time axis direction for each pixel (S200). Here, the display device 100 can perform the process of step S100 with a three-dimensional filter configured by, for example, a 2-tap low-pass filter and performing smoothing in the time axis direction and the surface direction. I can't.

  The display device 100 selectively suppresses the gain of the U signal and V signal (smoothed color signal) smoothed in step S200 (S202). Here, the display device 100 can selectively suppress the gains of the smoothed U signal and V signal for each pixel by using, for example, the above Equations 6 and 7. Not limited to.

  The display device 100 detects cross-color interference up-converted for each pixel based on the U signal and the V signal (S204). Here, the display device 100 can perform the process of step S204, for example, by deriving the degree of occurrence of cross-color interference related to the color vector deviation angle difference.

  The display device 100 detects movement for each pixel based on the Y signal (S206). Here, for example, the display device 100 can perform the process of step S206 by deriving a difference between the current frame and the previous frame for each pixel based on the Y signal, but is not limited thereto.

  The display device 100 detects a pixel that satisfies the cross-color interference occurrence condition based on the Y signal (S208). Here, for example, the display device 100 can perform the process of step S208 by deriving the degree of the high frequency component of the Y signal based on the diagonal high frequency component of the Y signal. I can't.

  FIG. 10 shows an example in which the processing of step S204, step S206, and step S208 is performed in order after the processing of step S200 and step S202. However, the display device 100 includes steps S200 and S202, Each process of S204-S208 can be performed independently. Therefore, the display device 100 can perform, for example, the order of steps S200 and S202 and the processes of steps S204 to S208 interchanged, and each process of steps S200 and S202 and steps S204 to S208. Can also be performed in synchronization with each other.

  The display device 100 sets a gain value for each pixel based on the detection results of the processes in steps S204 to S208 (S210). Here, the display device 100 can derive the gain value for each pixel using, for example, the above Equation 8 or the above Equation 9 and Equation 10.

  Based on the gain value set for each pixel in step S <b> 210, the display device 100 converts the U signal, V signal (input color signal), and the smoothed U signal, V signal (smoothed color signal) into pixels. Each is mixed (S212).

  By using the image processing method shown in FIG. 10, the display device 100 can perform the processes [2-1-A] to [2-1-E] described above. Therefore, the display device 100 using the image processing method shown in FIG. 10 reduces the up-converted cross-color interference (noise) related to Y / C separation on the basis of the input image signal for each pixel, thereby improving the image quality. Can be achieved.

  As described above, the display device 100 according to the embodiment of the present invention detects the cross-color interference that has been up-converted based on the color vector deviation difference for each pixel. More specifically, for example, the display device 100 includes, for example, [1-2A] (derivation of a color vector), [1-2B] (holding a color vector), and [1-2C] described above. (Derivation of color vector inner product), [1-2-D] (Derivation of degree of occurrence of cross-color interference) The degree of occurrence of cross-color interference relating to the color vector declination difference is derived. As described above, the declination difference of the color vector is the spatial / temporal when the up-converted cross-color interference occurs in the pseudo HD resolution image signal up-converted from the SD resolution image signal. It has the property of taking a certain amount of value regardless of the axis coordinates. Accordingly, the display apparatus 100 derives the degree of occurrence of cross color interference related to the color vector deviation difference based on the input image signal, thereby preventing the up-converted cross color interference related to Y / C separation. Can be detected.

  In addition, the display device 100 inverts the degree of occurrence of cross-color interference (the detection result of the up-converted cross-color interference) related to the deviation angle difference of the derived color vector and the cross-color interference component every other frame. By utilizing these properties, reduction of up-converted cross color interference (noise) is achieved for each pixel. More specifically, the display device 100, for example, includes the above-described [2-1-A] (smoothing in the time axis direction with respect to the input color signal), [2-1-B] (the gain of the smoothed color signal). Suppression), [2-1-C] (detection of pixels in which cross-color interference has occurred), [2-1-D] (setting of gain value), and [2-1-E] (to gain value) Based on the processing of the input color signal and the smoothed color signal based on the above, the reduction of the up-converted cross color interference is achieved. Here, as described above, the display device 100 can detect the up-converted cross color interference according to the degree of occurrence of the cross color interference related to the color vector deviation angle difference. Further, the property that the cross color interference component is inverted every other frame is not lost even in the up-converted pseudo HD resolution image signal. Therefore, the display device 100 performs the above-described processes [2-1-A] to [2-1-E], based on the input image signal, the up-converted cross-color interference (Y / C separation). Noise) can be reduced for each pixel, and high image quality can be achieved.

  Further, the display device 100 may set a gain value that defines a ratio for mixing the input color signal and the smoothed color signal based on a combination of detection results in the processes shown in the above [I] to [III]. it can. Accordingly, the display device 100 can reduce the up-converted cross-color interference with high accuracy for each pixel while more reliably preventing the occurrence of side effects such as blurring of the image.

(Program according to an embodiment of the present invention)
[Program for detection of up-converted cross-color interference]
By the program for causing the computer to function as the display device 100 (image processing device) according to the embodiment of the present invention, the up-converted cross-color interference related to Y / C separation is detected for each pixel based on the input image signal. Can be detected.

[Program for reducing up-converted cross-color interference]
A program for causing a computer to function as the display device 100 (image processing device) according to the embodiment of the present invention reduces up-converted cross-color interference related to Y / C separation based on an input image signal. High image quality can be achieved.

  As described above, the display device 100 (image processing device) has been described as a constituent element of the image processing system according to the embodiment of the present invention, but the embodiment of the present invention is not limited to such a form. Embodiments of the present invention include, for example, computers such as PCs and servers, portable communication devices such as mobile phones and PHS (Personal Handyphone System), PlayStation (registered trademark) series, PlayStation Portable (registered trademark), and the like. The present invention can be applied to various devices such as game machines, television receivers that receive television broadcasts and display images, organic EL displays, FEDs (Field Emission Displays), and display devices such as LCDs.

  In the above, preferred embodiments of the present invention have been described with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to such examples. 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 naturally within the technical scope of the present invention. Understood.

  For example, in the above description, it has been shown that a program (computer program) for causing a computer to function as a display device (image processing device) according to an embodiment of the present invention is provided. A storage medium storing the program can also be provided.

  The configuration described above shows an example of the embodiment of the present invention, and naturally belongs to the technical scope of the present invention.

It is explanatory drawing which shows an example of a structure of the image processing system which concerns on embodiment of this invention. It is a block diagram which shows the structural example of the display apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the hardware constitutions of the display apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the detection method of the up-converted cross color interference based on the deviation angle difference of the color vector which concerns on embodiment of this invention. It is a block diagram which shows the structural example which concerns on the detection process of the up-converted cross color interference in the image process part which concerns on embodiment of this invention. It is a flowchart which shows an example of the 1st image processing method which concerns on embodiment of this invention. It is explanatory drawing explaining an example of suppression of the gain of the smoothing color signal which concerns on embodiment of this invention. It is explanatory drawing for demonstrating an example of the setting method of the gain value which concerns on embodiment of this invention. It is a block diagram which shows an example of the structure which concerns on the cross color interference reduction process in the image process part which concerns on embodiment of this invention. It is a flowchart which shows an example of the 2nd image processing method which concerns on embodiment of this invention.

Explanation of symbols

Reference Signs List 104 Image processing unit 150 Color vector deriving unit 152 Color vector holding unit 154 Inner product deriving unit 156 Cross color interference determining unit 200 Three-dimensional filter 202 Gain suppressing unit 204 Cross color interference detecting unit 206 Motion detecting unit 208 Cross color interference generating condition detecting unit 210 Gain setting unit 212 Mixing unit

Claims (7)

A color vector deriving unit for deriving a color vector based on the input color signal input;
A color vector holding unit for holding the color vector derived by the color vector deriving unit;
An inner product value of the color vectors is derived based on the first color vector corresponding to the current frame derived by the color vector deriving unit and the second color vector corresponding to the previous frame held in the color vector holding unit. An inner product deriving unit;
A cross color interference determination unit for deriving a degree of occurrence of cross color interference based on the first vector, the second vector, and the inner product value derived by the inner product deriving unit;
An image processing apparatus comprising: A filter for smoothing the input color signal in the time axis direction;
A gain setting unit that sets, for each pixel, a gain value that defines a ratio of mixing the input color signal and the smoothed color signal smoothed by the filter based on a determination result in the cross color interference determination unit;
A mixing unit that mixes the input color signal and the smoothed color signal for each pixel based on the gain value set for each pixel;
The image processing apparatus according to claim 1, comprising: A motion detector for detecting a motion amount for each pixel based on a correlation between the input luminance signal corresponding to the input current frame and the previous frame input luminance signal corresponding to the previous frame;
The image processing apparatus according to claim 2, wherein the gain setting unit further sets the gain value for each pixel based on the amount of motion detected by the motion detection unit. A cross color interference generation condition detection unit that detects, for each pixel, a pixel that satisfies a condition for generating cross color interference based on the input luminance signal;
The image processing apparatus according to claim 3, wherein the gain setting unit further sets the gain value for each pixel based on a detection result of the cross color interference occurrence condition detection unit. A gain suppression unit that multiplies the smoothed color signal by a gain suppression value corresponding to the absolute value of the smoothed color signal for each pixel.
The image processing apparatus according to claim 2, wherein the mixing unit mixes the input color signal and a smoothed color signal multiplied by the gain suppression value for each pixel. Deriving a color vector based on the input color signal input;
Holding the color vector derived in the step of deriving the color vector;
Based on the first color vector corresponding to the current frame derived in the step of deriving the color vector and the second color vector corresponding to the previous frame retained in the retaining step, an inner product value of the color vectors is calculated. Deriving steps;
Deriving the degree of occurrence of cross-color interference based on the first vector, the second vector, and the inner product value derived in the step of deriving the inner product value;
An image processing method. Deriving a color vector based on the inputted input color signal;
Retaining the color vector derived in the step of deriving the color vector;
Based on the first color vector corresponding to the current frame derived in the step of deriving the color vector and the second color vector corresponding to the previous frame retained in the retaining step, an inner product value of the color vectors is calculated. Deriving step;
Deriving the degree of occurrence of cross-color interference based on the first vector, the second vector, and the inner product value derived in the step of deriving the inner product value;
A program that causes a computer to execute.

Images