JP2006333316A - Image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of executing contour enhancement wherein production of color slippage and the occurrence of black framing at edge parts of an image are suppressed to the utmost extent. <P>SOLUTION: A color edge enhancing section 14 obtains a first image component on the basis of a first arithmetic operation (color ratio keeping system) wherein a color ratio is unchanged before and after the processing of the contour enhancement, obtains a second image component on the basis of a second arithmetic operation (color difference keeping system) wherein a color difference is unchanged before and after the processing of the contour enhancement, the contour enhancement of an image is carried out by mixing the first and the second image components on the basis of a mixing ratio k so that good points of the color ratio keeping system and the color difference keeping system are respectively combined to execute excellent contour enhancement wherein production of the color slippage and occurrence of the black framing at the edge parts are suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, and is particularly suitable for use in an apparatus that performs contour emphasis processing that makes an image contour stand out.

  In general, as shown in FIG. 11, the edge enhancement processing of an image corrects a luminance value on the (+) side (that is, the bright side) with respect to a portion where a low-brightness dark signal shifts to a high-brightness bright signal. Or the process of correcting the luminance value on the (−) side (that is, the dark side). The color representation method in the color image includes a YUV method for specifying a color by a luminance component (Y) and a color component (UV), and an RGB for specifying a color by red (R), green (G), and blue (B). There is a method. In the case of the YUV system, it is only necessary to adjust the intensity of the luminance value Y, so that the color component is not affected by the edge enhancement. On the other hand, in the case of the RGB method, the color component is affected by the edge enhancement.

  The following two methods exist as typical methods for enhancing the outline of an image in the RGB space. One is a method of preventing color differences such as RG, BG, and RB from changing before and after contour enhancement (hereinafter referred to as a color difference holding method). The other is a method in which the ratio of R: G: B is not changed before and after contour enhancement (hereinafter referred to as a color ratio holding method).

  In the color difference holding method, as shown in FIG. 12, the color difference does not change before and after contour enhancement, but the ratio of R: G: B changes. Therefore, when contour enhancement is performed, the chromaticity coordinates (x, y) change. End up. As the chromaticity coordinates (x, y), values of {X, Y, Z} obtained when a predetermined matrix of 3 × 3 is applied to the values of {R, G, B} are used. X = X / (X + Y + Z), y = Y / (X + Y + Z).

  That is, in the color difference holding method, from the chromaticity coordinates (x, y) obtained from the value of {R, G, B} before contour enhancement and the value of {R ′, G ′, B ′} after contour enhancement. The required chromaticity coordinates (x ′, y ′) are not equal. This means that when edge enhancement is performed, a color shift occurs and the color after edge enhancement is different from the color before edge enhancement. Specifically, when the brightness is enhanced on the (+) side, the ratio of R: G: B approaches 1: 1: 1 and the color becomes lighter. On the contrary, if the brightness is emphasized on the (−) side, the ratio of R: G: B moves away from 1: 1: 1 and the color becomes darker.

On the other hand, in the color ratio holding method, since the ratio of R: G: B does not change before and after contour enhancement, the chromaticity coordinates (x, y) are unchanged even when contour enhancement is performed. That is, the chromaticity coordinates (x, y) obtained from the {R, G, B} values before contour enhancement and the chromaticity coordinates obtained from the {R ′, G ′, B ′} values after contour enhancement. (X ′, y ′) becomes equal. This means that color misalignment does not occur even when contour enhancement is performed. In addition, a technique for the purpose of enabling edge enhancement without causing color misregistration in the RGB space has been proposed (see, for example, Patent Document 1).
JP 2001-169305 A

  However, when the edge enhancement process is performed by the color ratio holding method, there arises a problem that black borders become conspicuous in the edge portion of the image. In particular, compared with the case where the luminance value is corrected to the (+) side by edge enhancement, the black border becomes very conspicuous when the luminance value is corrected to the (−) side. This phenomenon is considered to be caused by the fact that when the image becomes dark even if the chromaticity coordinates are the same, the color disappears and appears black to the human eye.

  The present invention has been made to solve such a problem, and is capable of performing edge enhancement that suppresses occurrence of color misregistration and occurrence of black bordering at an edge portion of an image as much as possible. With the goal.

In order to solve the above-described problem, in the present invention, the first image component is obtained based on the first calculation so that the color ratio does not change before and after the contour enhancement process, and the color difference between before and after the contour enhancement process. The second image component is obtained on the basis of the second calculation so as not to change, and the first image component and the second image component are mixed to enhance the contour of the image.
In another aspect of the present invention, the mixing ratio between the first image component and the second image component is determined based on the respective values of the luminance component before contour enhancement and the luminance component after contour enhancement. ing.

  According to the present invention configured as described above, the edge enhancement by the first image component obtained based on the first calculation that prevents the color ratio from being changed before and after the process, and the color difference before and after the process are changed. The edge enhancement by the second image component obtained based on the second calculation to avoid the color behaves in the opposite direction with respect to the color. That is, the first image component can make the contour stand out without causing a color shift. This alone may cause a black border at the edge portion of the image. However, by mixing the second image component and suppressing the influence of the first image component, the first image component causes a color shift. While suppressing, generation | occurrence | production of the black border in an edge part can also be suppressed.

  That is, according to the present invention, the first image component and the second image component are mixed at an appropriate mixing ratio, thereby suppressing the occurrence of color misregistration and the occurrence of black bordering at the edge portion of the image as much as possible. Edge enhancement can be performed. In addition, the mixing ratio in that case is determined based on the respective values of the luminance component before contour enhancement and the luminance component after contour enhancement, so that the color tone is just right according to the content of contour enhancement. Outline enhancement can be realized.

  For example, if the luminance component after contour enhancement is larger than the luminance component before contour enhancement, that is, the contour enhancement to the (+) side, even if edge enhancement is performed using the color ratio holding method, the black border at the edge portion is not much. Inconspicuous. Therefore, in this case, the occurrence of color misregistration can be suppressed as much as possible by making the mixing ratio of the first image component larger than that of the second image component. On the other hand, when the luminance component after contour enhancement is smaller than the luminance component before contour enhancement, that is, in the case of contour enhancement on the (−) side, if edge enhancement is performed only by the color ratio holding method, the color of the edge portion is lost and black The border is noticeable. Therefore, in this case, by increasing the mixing ratio of the second image components, it is possible to suppress the occurrence of black bordering at the edge portion as much as possible.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram illustrating a configuration example of a main part of an image processing apparatus 10 according to the first embodiment. FIG. 2 is a block diagram illustrating a partial configuration example of the digital camera 20 to which the image processing apparatus 10 according to the first embodiment is applied. FIG. 3 is a flowchart showing the content of the edge enhancement processing performed by the image processing apparatus 10 of the first embodiment.

  As shown in FIG. 2, the digital camera 20 includes an optical system 21 including a shutter, a lens, an iris, an image sensor 22 such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and an A / D. A converter 23, a color interpolation unit 24, a contour enhancement unit 25, a γ correction unit 26, and a signal separation unit 27 are provided.

  In the digital camera 20 configured as described above, light from the subject is imaged by the image sensor 22 via the optical system 21. The imaging element 22 photoelectrically converts the incident light that has been imaged and generates an analog imaging signal corresponding to the incident light. The imaging signal generated here is supplied to the A / D converter 23 and converted into a digital image signal.

  The digital image signal obtained by the A / D converter 23 is sequentially subjected to color interpolation processing, contour enhancement processing, noise suppression processing, γ correction processing, and the like by the color interpolation unit 24, the contour enhancement unit 25, and the γ correction unit 26. Is done. The contour enhancement process is a process for enhancing the edge of the image, and the noise suppression process is a process for suppressing the edge of the image. That is, since these processes are front and back integrated processes, they are executed by the contour emphasizing unit 25. The color interpolation unit 24, the contour enhancement unit 25, and the γ correction unit 26 can be configured as a hardware logic circuit, or can be configured by a DSP (Digital Signal Processor).

The signal separation unit 27 performs a process of separating the image signal input from the γ correction unit 26 into a luminance signal and a color difference signal. That, R · G · B which is input from the γ correcting unit 26 (red, green, blue) three primary color signals of the luminance signal Y _· C b · C _r, the color difference signals and blue, to red color difference signal Convert. A known method can be applied to this conversion process, and a detailed description thereof is omitted here. Various processes such as a chroma suppression process are performed on the luminance signal Y and the color difference signals C _b and C _r separated by the signal separation unit 27, but the configuration for this is not shown.

  The above-described outline emphasizing unit 25 is a part corresponding to the image processing apparatus 10 of the present embodiment. As shown in FIG. 1, the image processing apparatus 10 according to the present embodiment includes, as its functional configuration, a luminance extraction unit 11, a luminance edge enhancement unit 12, a mixing ratio determination unit 13, and a color edge enhancement unit 14 (present invention). Equivalent to the contour emphasis calculating means). Hereinafter, the contents of the processes performed by these units 11 to 14 will be specifically described with reference to the flowchart of FIG.

The luminance extraction unit 11 extracts a luminance component Y from an image signal input as a contour enhancement processing target by the color edge enhancement unit 14. The image signal input to the luminance extraction unit 11 is an RGB three primary color signal. The luminance extraction unit 11 obtains the luminance component Y of the image by the following (Expression 1) using predetermined coefficients kr, kg, kb (kr + kg + kb = 1) based on the R, G, B components.
Y = kr * R + kg * G + kb * B (Formula 1)

  The luminance edge enhancement unit 12 performs contour enhancement processing on the (+) side or the (−) side with respect to the luminance component Y obtained by the luminance extraction unit 11. Which of the edge enhancement processes to the (+) side or (−) side is determined as follows, for example. An edge component is extracted from the image before contour enhancement. If the edge component has a (+) edge component, the contour enhancement is performed on the (+) side. If it has a (−) edge component, the contour enhancement is performed on the (−) side. . When contour enhancement to the (+) side is performed, the magnitude relationship between the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement is Y <Y ′. On the other hand, when contour enhancement to the (−) side is performed, the magnitude relationship between the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement is Y> Y ′.

  Note that noise suppression may be performed simultaneously with such contour enhancement. As for edge enhancement and noise suppression, a known method can be applied as long as it is for a one-component image such as a gray scale, and the detailed description thereof is omitted here.

  Based on the respective values of the luminance component Y before contour enhancement extracted by the luminance extraction unit 11 and the luminance component Y ′ after contour enhancement performed by the luminance edge enhancement unit 12, the mixing ratio determination unit 13 A mixing ratio k between a first image component and a second image component, which will be described later, is determined. Details of the method for determining the mixing ratio k will be described later.

  The color edge emphasizing unit 14 based on the R, G, and B components, the first image component based on the first calculation (color ratio holding method) that prevents the color ratio from changing before and after the contour emphasis process. Ra ′, Ga ′, and Ba ′ are obtained, and second image components Rb ′, Gb ′, and Bb ′ are obtained based on a second calculation (color difference holding method) that prevents the color difference from changing before and after the contour enhancement process. Ask for. Then, the first image components Ra ′, Ga ′, Ba ′ obtained by the color ratio holding method and the second image components Rb ′, Gb ′, Bb ′ obtained by the color difference holding method are mixed into the mixing ratio determining unit 13. The images R ′, G ′, and B ′ whose outlines are enhanced in the RGB space are obtained by mixing based on the mixing ratio k determined by the above.

Here, the first image components Ra ′, Ga ′, and Ba ′ are obtained based on the following (Formula 2).
Ra ′ = α × R, Ga ′ = α × G, Ba ′ = α × B (Formula 2)
However, α = Y ′ / Y
Further, the second image components Rb ′, Gb ′, and Bb ′ are obtained based on the following (Expression 3).
Rb ′ = R + β, Gb ′ = G + β, Bb ′ = B + β (Formula 3)
However, β = Y′−Y

Further, the mixing of the first image components Ra ′, Ga ′, Ba ′ and the second image components Rb ′, Gb ′, Bb ′ is performed based on the following (Formula 4).
R ′ = (1−k) × Ra ′ + k × Rb ′
G ′ = (1−k) × Ga ′ + k × Gb ′
B ′ = (1−k) × Ba ′ + k × Bb ′ (Formula 4)

Here, the value of the mixing ratio k is determined as follows, for example. That is, according to the sign of Y′−Y, k = 0 when the sign is positive (Y <Y ′), and k = k _T when the sign is negative (Y> Y ′). To do. Note that k _T is a value that has been experimentally obtained in advance so as to achieve a contour emphasis with a good color. In this method, in the case of edge enhancement to the (+) side, even if the edge enhancement is performed by the color ratio holding method, the black border at the edge portion is not conspicuous. Therefore, the first image component Ra obtained by the color ratio holding method is used. Only ', Ga' and Ba 'are employed. However, in the case of edge enhancement to the (−) side, the black border in the edge portion becomes conspicuous only with the color ratio holding method, and therefore, the first image components Ra ′, Ga ′, Ba ′ and the first image components at a predetermined ratio. The two image components Rb ′, Gb ′, and Bb ′ are to be mixed.

  The method for determining the mixing ratio k is not limited to this. For example, the specific value of the mixture ratio k may be determined according to the magnitude of the difference between the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement. In this case, the mixing ratio determination unit 13 has table information in which the difference value between the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement is associated with the value of the mixing ratio k, and the table information is The value of the mixing ratio k is determined by referring to it.

  As described above in detail, according to the first embodiment, the first image components Ra ′, Ga ′, and Ba ′ are obtained by the color ratio holding method, and the second image components Rb ′, by the color difference holding method. Gb ′ and Bb ′ are obtained, and these are mixed to enhance the contour of the image. Thus, by combining the good points of the color ratio holding method and the color difference holding method, it is possible to perform excellent edge enhancement in which occurrence of color misregistration and black bordering at the edge portion is suppressed.

  In addition, according to the first embodiment, the first image components Ra ′, Ga ′, Ba ′ and the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement are based on the respective values. The mixing ratio k with the second image components Rb ′, Gb ′, Bb ′ is determined. As a result, the first image components Ra ′, Ga ′, Ba ′ and the first image components Ra ′, Ga ′, Ba ′ are more preferably selected depending on whether the contour is emphasized on the (+) side or on the (−) side. The second image components Rb ′, Gb ′, and Bb ′ can be mixed, and contour emphasis can be realized so that the color tone is just right.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a functional block diagram illustrating a configuration example of a main part of the image processing apparatus 30 according to the second embodiment. FIG. 5 is a block diagram illustrating a partial configuration example of a digital camera 40 to which the image processing apparatus 30 according to the second embodiment is applied. FIG. 6 is a flowchart showing the content of the contour emphasis process performed by the image processing apparatus 30 according to the second embodiment.

In FIG. 5, components having the same functions as those shown in FIG. In the second embodiment, as illustrated in FIG. 5, the signal separation unit 27 converts the R, G, and B primary color signals into the luminance signal Y and the color difference signals C _b and C _r , and then the contour enhancement unit 41 performs conversion. Perform edge enhancement processing. In the case of this configuration, the signal separation unit 27 constitutes the luminance extraction means of the present invention.

  The contour emphasizing unit 41 is a part corresponding to the image processing device 30 according to the second embodiment. As shown in FIG. 4, the image processing apparatus 30 of the present embodiment has, as its functional configuration, a luminance edge enhancement unit 12, a mixture ratio determination unit 13, and a color edge enhancement unit 31 (in the contour enhancement calculation unit of the present invention). Equivalent). In FIG. 4, components having the same functions as those shown in FIG. 1 are given the same reference numerals, and redundant descriptions are omitted. Hereinafter, the operation of the image processing apparatus 30 will be specifically described with reference to the flowchart of FIG. 6, focusing on the contents of the processing performed by the color edge enhancement unit 31 that does not overlap with the configuration of FIG. 1.

Based on the respective values of the luminance component Y before contour enhancement extracted by the signal separation unit 27 and the luminance component Y ′ after contour enhancement performed by the luminance edge enhancement unit 12, the mixing ratio determination unit 13 the first image component _C b _{a', C} r a'and second image component _C b _b', determines the mixing ratio k between _C r b'. The method for determining the mixing ratio k may be the same as in the first embodiment.

The color edge enhancement unit 31 obtains first image components C _{b a ′} and C _{r a} ′ according to the color ratio holding method based on the color difference components C _b and C _r input from the signal separation unit 27, and the color difference. The second image components C _{b b} ′ and C _r b ′ are obtained according to the holding method. Then, the first image component _C b a'determined by the color ratio maintenance _{system, C} r a'and second image component _C b b'determined by the color-difference holding _method, and _C r b', mixing ratio determination By performing mixing based on the mixing ratio k determined by the unit 13, color difference signals C _b ′ and C _r ′ in which the contour is enhanced in the YUV space are obtained. Note that the luminance signal Y ′ whose edge has been enhanced in the YUV space is obtained by the luminance edge enhancement unit 12.

Here, the first image components C _{b a ′} and C _{r a} ′ are obtained based on the following (formula 5).
C _{b a ′} = α × C _b , C _{r a ′} = α × C _r , (Formula 5)
However, α = Y ′ / Y
The second image components C _{b b} ′ and C _r b ′ are obtained based on the following (Expression 6).
C _{b b} ′ = C _b , C _r b ′ = C _r (Expression 6)
The first image component _C b _{a', C} r a'and second image component _C b _b', mixing with the _C r b'is performed based on the following equation (7).
_{C b '= (1-k} ) × C b a'+ k × C b b'
_{C r '= (1-k} ) × C r a'+ k × C r b'··· ( Equation 7)

As described above in detail, according to the second embodiment, the color ratio maintenance method first image component C _b a', C r _a'with obtaining a second image component C _b color difference retention system The contour enhancement of the image is performed by obtaining b ′ and C _r b ′ and mixing them. Thus, by combining the good points of the color ratio holding method and the color difference holding method, it is possible to perform excellent edge enhancement in which occurrence of color misregistration and black bordering at the edge portion is suppressed.

According to the second embodiment, the first image components C _{b a ′} and C _{r a} ′ are based on the values of the luminance component Y before contour enhancement and the luminance component Y ′ after contour enhancement. And the second image component C _{b b} ′ and C _r b ′ are determined. As a result, the first image components C _{b a ′} and C _{r a} ′ are selected depending on whether the outline is emphasized on the (+) side or the outline is emphasized on the (−) side, more preferably, depending on the degree of enhancement. And the second image components C _{b b} ′ and C _r b ′ can be mixed, and the contour enhancement can be realized so as to have a good color.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to the drawings. In the third embodiment, three primary color image signals R, G, B or the color difference signal C _b, false color suppression low pass filter processing on the C _r, the edge enhancement processing by using the signal thus obtained It is what I do.

  FIG. 7 is a functional block diagram illustrating a configuration example of a main part of an image processing device 50 according to the third embodiment in which a false color suppression low-pass filter is added to the image processing device 10 illustrated in the first embodiment. FIG. 8 is a flowchart showing the content of the contour enhancement processing performed by the image processing apparatus 50 according to the third embodiment. In FIG. 7, components having the same reference numerals as those shown in FIG. 1 have the same functions, and thus redundant description is omitted here.

  FIG. 9 is a functional block diagram illustrating a configuration example of a main part of an image processing apparatus 60 according to the third embodiment in which a false color suppression low-pass filter is added to the image processing apparatus 30 illustrated in the second embodiment. FIG. 10 is a flowchart showing the content of the contour enhancement processing performed by the image processing device 60 according to the third embodiment. Note that, in FIG. 9, those given the same reference numerals as those shown in FIG. 4 have the same functions, and thus redundant description is omitted here.

  As shown in FIGS. 7 and 8, the false color suppression low-pass filter 51 performs false color suppression low-pass filter processing on the image signals R, G, and B that are input as the contour emphasis processing targets. Image signals Rf, Gf, and Bf that are suppressed are obtained. A known method can be applied to the filtering process, and the detailed description thereof is omitted here.

The second luminance extraction unit 52 uses the predetermined coefficients kr, kg, kb (kr + kg + kb = 1) based on the image signals Rf, Gf, Bf obtained by the false color suppression low-pass filter 51, and uses the following ( The luminance component Yf of the image is obtained by Expression 8).
Yf = kr × Rf + kg × Gf + kb × Bf (Equation 8)
Note that the luminance extraction unit 11 may be omitted, and the luminance edge enhancement unit 12 may perform enhancement processing on the luminance component Yf extracted by the second luminance extraction unit 52.

  The color edge enhancement unit 53 obtains the first image components Ra ′, Ga ′, and Ba ′ according to the color ratio holding method based on the components of Rf, Gf, and Bf whose false colors are suppressed, and performs the first operation according to the color difference holding method. Two image components Rb ′, Gb ′, and Bb ′ are obtained. Then, the first image components Ra ′, Ga ′, Ba ′ and the second image components Rb ′, Gb ′, Bb ′ are mixed based on the mixing ratio k determined by the mixing ratio determination unit 13. Thus, the images R ′, G ′, and B ′ whose outlines are enhanced in the RGB space are obtained. When obtaining the edge-enhanced image signals R ′, G ′, and B ′, Rf, Gf, and Bf are used instead of R, G, and B as the image signals before edge enhancement, and luminance components before edge enhancement are used. The second embodiment is the same as the first embodiment except that Yf is used instead of Y.

Also, as shown in FIGS. 9 and 10, the false color suppression low-pass filter 61 performs false color suppression low-pass filter processing on the color difference signals C _b and C _r that are input as contour enhancement processing targets. Color difference signals C _b f and C _r f in which false colors are suppressed are obtained. A known method can be applied to the filtering process, and the detailed description thereof is omitted here.

The color edge enhancement unit 62 obtains the first image components C _{b a ′} and C _{r a} ′ according to the color ratio holding method based on the false color-suppressed components of C _b f and C _r f and holds the color difference. The second image components C _{b b} ′ and C _r b ′ are obtained according to the method. Then, the first image component _C b _{a', C} r a'and second image component _C b _b', and _C r b', based on the mixing ratio k which is determined by the mixing ratio determining unit 13 mixture As a result, the images C _b ′ and C _r ′ whose contours are enhanced in the YUV space are obtained. The second difference except that C _b f and C _r f are used instead of C _b and C _r as color difference signals before edge enhancement when obtaining the edge enhanced color difference signals C _b ′ and C _r ′. This is the same as the embodiment.

  In the first to third embodiments, (Equation 2) and (Equation 5) are given as examples of arithmetic expressions for the color ratio holding method, and (Equation 3) and (Equation 6) are used as arithmetic expressions for the color difference holding method. ) As an example, but is not limited thereto. As long as the arithmetic expression holds the color ratio or the arithmetic expression holds the color difference, other arithmetic expressions can be applied.

  In the first to third embodiments, the example in which the first image component and the second image component are mixed by a linear operation such as (Expression 4) and (Expression 7) has been described. It is not limited to this. Any other arithmetic expression can be applied as long as it is an arithmetic expression that mixes the first image component and the second image component based on the mixing ratio k.

  In the first to third embodiments, FIGS. 2 and 5 are exemplified as the configuration of the digital camera to which the image processing apparatus of the present invention is applied. However, the present invention is not limited to this. For example, the processing of the color interpolation unit 24 and the γ correction unit 26 may be omitted or the order may be changed. Further, other processing blocks (not shown) may be added.

  In the first to third embodiments, the example in which the image processing apparatus of the present invention is implemented in a digital camera has been described. However, an electronic device that can be implemented is not limited to a digital camera. The present invention can be widely applied to electronic devices that handle image signals.

  In addition, each of the first to third embodiments described above is merely an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. It will not be. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

  The image processing apparatus of the present invention can be widely used in image processing apparatuses that need to process image signals. For example, it is useful for a digital camera, a video camera, a television receiver, a DVD (Digital Versatile Disk) player, and the like. Further, the present invention can be applied not only to digital signal processing but also to an image processing apparatus that performs analog signal processing.

FIG. 2 is a functional block diagram illustrating a configuration example of a main part of the image processing apparatus according to the first embodiment. 1 is a block diagram illustrating a partial configuration example of a digital camera to which an image processing apparatus according to a first embodiment is applied. It is a flowchart which shows the content of the outline emphasis process performed by the image processing apparatus of 1st Embodiment. It is a functional block diagram which shows the principal part structural example of the image processing apparatus by 2nd Embodiment. It is a block diagram which shows the example of a partial structure of the digital camera to which the image processing apparatus by 2nd Embodiment is applied. It is a flowchart which shows the content of the outline emphasis process performed by the image processing apparatus of 2nd Embodiment. It is a functional block diagram which shows the principal part structural example of the image processing apparatus by 3rd Embodiment. It is a flowchart which shows the content of the outline emphasis process performed by the image processing apparatus of FIG. It is a functional block diagram which shows another example of a principal part structure of the image processing apparatus by 3rd Embodiment. FIG. 10 is a flowchart showing the content of contour enhancement processing performed by the image processing apparatus of FIG. 9. FIG. It is a figure which shows the concept of the general outline enhancement process of an image. It is a figure which shows the concept of the outline emphasis process by a color difference retention system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30, 50, 60 Image processing apparatus 11 Luminance extraction part 12 Luminance edge emphasis part 13 Mixing ratio determination part 14, 31, 53, 62 Color edge emphasis part 25, 41 Outline emphasis part 27 Signal separation part 51, 61 False color Suppressing low-pass filter 52 Second luminance extraction unit

Claims (2)

The first image component is obtained based on the first calculation that prevents the color ratio from changing before and after the contour emphasis process, and the second calculation that prevents the color difference from changing before and after the contour emphasis process. Contour enhancement computing means for obtaining a second image component and performing contour enhancement of the image by mixing the first image component and the second image component based on a given mixture ratio;
An image processing apparatus comprising: a mixing ratio determining unit that determines the mixing ratio. A luminance extracting means for extracting a luminance component from the image signal to be processed by the contour enhancement calculating means;
The mixing ratio determining means determines the mixing ratio based on respective values of the luminance component before contour enhancement extracted by the luminance extraction means and the luminance component after contour enhancement. Item 8. The image processing apparatus according to Item 1.

Images