JP2012004772A - Image display device, image supply device, image processing method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress clipping of overshoot and undershoot in contour emphasis processing.SOLUTION: A projector comprises: a brightness adjustment unit 32 which adjusts the brightness of input image data to generate adjusted image data; and a contour emphasis unit 30 which performs the contour emphasis processing on the adjusted image data generated by the brightness adjustment unit 32 to generate contour-emphasized image data. The projector projects an image on a projection surface on the basis of the contour-emphasized image data generated by the contour emphasis unit 30.

Description

  The present invention relates to an image display device that performs contour enhancement processing on input image data, an image supply device, an image processing method related to contour enhancement processing, and a program for executing contour enhancement processing.

  2. Description of the Related Art Conventionally, an image display device (projection-type video display device) that performs contour enhancement processing on input image data in order to improve the sharpness of an image projected on a projection surface is known (for example, Patent Document 1). reference). In the contour emphasis processing, the luminance of the pixel is corrected by adding overshoot or undershoot to the contour portion (pixel corresponding to the contour) with respect to the input image data, thereby enhancing the contour.

JP 2006-253838 A

However, as in the case of the image display device described above, when correcting the luminance of a pixel by adding undershoot or overshoot to the contour portion of the input image data, Thus, since it is impossible to correct the luminance beyond the range of the luminance gradation value of the pixel, there is a problem that a part of the overshoot or undershoot may be clipped.
In addition, when brightness adjustment (luminance correction) is performed on input image data after performing contour enhancement processing using overshoot or undershoot, it corresponds to the contour portion where overshoot or undershoot has occurred. Brightness adjustment is also performed on the pixels, and there is a problem that sharpness due to edge enhancement is reduced.
The present invention has been made in view of the above-described circumstances, and suppresses overshooting and undershooting from being clipped during the contour emphasis process, and prevents the sharpness due to the contour emphasis process from being lowered. With the goal.

In order to achieve the above object, the present invention is an image display device that is generated by a brightness adjustment unit that adjusts the brightness of input image data and generates adjusted image data, and the brightness adjustment unit. An edge emphasis process is performed on the adjusted image data, and an image is projected onto a projection surface based on the edge emphasis unit that generates edge emphasis image data and the edge emphasis image data generated by the edge emphasis unit. And an image display unit.
According to this configuration, the contour emphasis process is performed on the adjusted image data generated by adjusting the brightness of the input image data. That is, an adjustment image in which the difference formed between the luminance value in each pixel and the upper limit value or lower limit value of the luminance gradation value is larger than the input image data before the brightness is adjusted. Since overshoot and undershoot are added to the data, overshoot and undershoot clipping can be suppressed.
Further, according to the above configuration, since the edge enhancement processing is performed on the input image data subjected to the brightness adjustment, the pixels of the contour portion and the pixels adjacent to the contour portion in the input image data after the contour enhancement processing are The brightness gap can be prevented from being reduced by brightness adjustment, and the sharpness of the image projected on the projection surface by the image display unit can be prevented from being lowered.

Here, in the image display device according to the invention described above, the contour emphasizing unit overshoots the adjusted image data generated by reducing the brightness of the input image data by the brightness adjusting unit. You may perform the outline emphasis process using.
According to this configuration, the difference formed between the luminance value in each pixel and the upper limit value of the luminance gradation value is larger than the input image data before the brightness is adjusted. Since overshoot is added to the image data, overshoot clipping can be suitably suppressed.
Further, according to the above configuration, since the edge enhancement process is performed on the input image data that has been adjusted to reduce the brightness, the pixels of the edge portion in the input image data after the edge enhancement process using overshoot, It is possible to suppress the reduction in the luminance gap between the pixels adjacent to the portion due to the brightness adjustment, and it is possible to prevent the sharpness of the image projected on the projection surface from being reduced by the image display unit.

Further, in the image display device according to the invention, the contour emphasizing unit extracts contours of the input image data to generate contour emphasizing data including overshoots, and the adjustment image data with respect to the adjustment image data. Contour emphasis processing using overshoot may be executed by synthesizing contour emphasis data.
According to this configuration, the contour enhancement data including overshoot is generated after the contour is extracted from the input image data before the brightness adjustment unit performs the adjustment to lower the brightness. For this reason, the overshoot included in the contour enhancement data is calculated based on the input image data that has not been subjected to the correction of the luminance of the pixel by the brightness adjustment, that is, not affected by the process related to the brightness adjustment. Therefore, it is possible to prevent the overshoot value from being excessively small or excessive, and maintain the appropriateness of the value.

The image display device according to the invention further includes an input unit for adjusting an input / output gain, and the brightness adjusting unit performs an adjustment to lower the input / output gain with respect to the input unit. When there is an input, the adjusted image data may be generated by reducing the brightness of the input image data in accordance with an adjustment for reducing the input / output gain based on the input.
According to this configuration, when there is an input for performing an adjustment to lower the input / output gain to the input unit, it is possible to prevent overshoot clipping by using the decrease in the input / output gain based on the input.
In particular, conventionally, when adjustment for lowering the input / output gain is performed based on the input for performing the adjustment for lowering the input / output gain for the input unit, the sharpness may be lowered at the same time. According to the said structure, the fall of the said sharpness can be prevented.

Further, in the image display device according to the invention, an illuminance sensor that detects illuminance of an environment in which the projection surface is provided, and a gain adjustment unit that adjusts an input / output gain according to a detection value of the illuminance sensor, The brightness adjustment unit may generate the adjusted image data by reducing the brightness of the input image data in accordance with an adjustment for reducing the input / output gain by the gain adjustment unit.
According to this configuration, the input / output gain can be adjusted appropriately according to the brightness around the projection surface, and overshoot clipping can be suppressed when the gain is adjusted to be reduced.

In the image display device according to the above invention, the contour emphasizing unit may undershoot the adjusted image data generated by increasing the brightness of the input image data by the brightness adjusting unit. You may perform the utilized outline emphasis process.
According to this configuration, the difference formed between the luminance value in each pixel and the lower limit value of the luminance gradation value is larger than the input image data before the brightness is adjusted. Undershoot is added to the image data, so undershoot clipping can be suitably suppressed.
Further, according to the above configuration, since the edge enhancement process is performed on the input image data that has been adjusted to increase the brightness, the pixels of the edge portion in the input image data after the edge enhancement process using the undershoot, It is possible to suppress the reduction in the luminance gap between the pixels adjacent to the portion due to the brightness adjustment, and it is possible to prevent the sharpness of the image projected on the projection surface from being reduced by the image display unit.

In order to achieve the above object, the present invention provides an image supply device that supplies image data to an image display device, and adjusts the brightness of input image data to generate adjusted image data. A contour emphasizing unit that performs contour emphasis processing on the adjusted image data generated by the brightness adjusting unit and generates contour emphasized image data.
According to this configuration, the contour emphasis process is performed on the adjusted image data generated by adjusting the brightness of the input image data. That is, an adjustment image in which the difference formed between the luminance value in each pixel and the upper limit value or lower limit value of the luminance gradation value is larger than the input image data before the brightness is adjusted. Since overshoot and undershoot are added to the data, overshoot and undershoot clipping can be suppressed.
Further, according to the above configuration, since the edge enhancement processing is performed on the input image data subjected to the brightness adjustment, the pixels of the contour portion and the pixels adjacent to the contour portion in the input image data after the contour enhancement processing are The brightness gap can be prevented from being reduced by brightness adjustment, and the sharpness of the image projected on the projection surface by the image display unit can be prevented from being lowered.

In order to achieve the above object, the present invention is an image processing method, wherein adjusted image data is generated by adjusting brightness of input image data, and contour enhancement processing is performed on the generated adjusted image data. It is characterized by performing.
Furthermore, it is a program that causes an image supply apparatus that supplies image data to an image display apparatus to execute the above-described image processing method.
According to the image processing method and the program for executing the image processing method, the contour enhancement process is executed on the adjusted image data generated by adjusting the brightness of the input image data. That is, an adjustment image in which the difference formed between the luminance value in each pixel and the upper limit value or lower limit value of the luminance gradation value is larger than the input image data before the brightness is adjusted. Since overshoot and undershoot are added to the data, overshoot and undershoot clipping can be suppressed.
Further, according to the above configuration, since the edge enhancement processing is performed on the input image data subjected to the brightness adjustment, the pixels of the contour portion and the pixels adjacent to the contour portion in the input image data after the contour enhancement processing are The brightness gap can be prevented from being reduced by brightness adjustment, and the sharpness of the image projected on the projection surface by the image display unit can be prevented from being lowered.

  According to the present invention, it is possible to suppress overshoot and undershoot from being clipped during the contour enhancement process, and to prevent the sharpness due to the contour enhancement process from being lowered.

1 is a block diagram showing a functional configuration of a projector according to a first embodiment. It is a block diagram which shows the functional structure of an outline emphasis part. It is a figure for demonstrating the data for outline emphasis. The figure for demonstrating the synthesis | combination of adjustment image data and the data for outline emphasis. It is a flowchart which shows operation | movement of an outline emphasis part. (A) is a figure which shows the mode of change of input image data when the conventional projector performs the outline emphasis process using overshoot, and a brightness adjustment process, (B) is a figure in this embodiment. It is a figure which shows the mode of the change of input image data in case the projector which concerns performs the said process. (A) is a figure which shows the mode of change of input image data when the conventional projector performs the outline emphasis process using overshoot, and a brightness adjustment process, (B) is a figure in this embodiment. It is a figure which shows the mode of the change of input image data in case the projector which concerns performs the said process. The block diagram which shows the functional structure of the projector which concerns on 2nd Embodiment. It is a flowchart which shows operation | movement of an outline emphasis part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a block diagram showing a functional configuration of a projector 1 (image display device).
The projector 1 is a device that projects an image on a projection surface such as a screen based on image data (hereinafter referred to as “input image data”) indicated by a video signal input from an external device. The projector 1 has a function of enhancing the contour of an image projected on a projection surface by performing contour enhancement processing on input image data.
Note that the input image data is bitmap format data, and for each pixel arranged in a dot matrix on the data, the luminance of the RGB color component for each pixel is represented by a gradation value (for example, 0-256 levels). (Tone value).

As shown in FIG. 1, the projector 1 includes a light source lamp 10, a liquid crystal light valve 11, and a projection optical system 12. The light source lamp 10 is a light source that emits light. The liquid crystal light valve 11 is a light modulation element that modulates incident light based on the video signal, and modulates the light emitted from the light source lamp 10 based on the video signal. The projection optical system 12 adjusts the magnification of the light modulated by the liquid crystal light valve 11 and projects an image on the projection surface. In the present embodiment, the light source lamp 10, the liquid crystal light valve 11, and the projection optical system 12 cooperate to function as an image display unit.
Although not shown in FIG. 1, the projector 1 is provided with three liquid crystal light valves 11 and a circuit system for forming an image on each of the liquid crystal light valves 11 for each of the RGB colors. Light emitted from the light source lamp 10 is separated into three colors of RGB by a dichroic mirror, and light of each color is modulated by a liquid crystal light valve 11 of a corresponding color. Light modulated by each liquid crystal light valve 11 is combined by a dichroic prism and projected onto a projection surface via a projection optical system 12.

Further, the projector 1 includes a control unit 15, an input unit 16, a storage unit 17, a light source lamp driving unit 18, a liquid crystal light valve driving unit 19, a projection optical system adjustment unit 20, and an interface unit 21. I have.
The control unit 15 centrally controls each unit of the projector 1, and a CPU that stores a CPU as a calculation execution unit and a basic control program executed by the CPU in a computer-readable form in a nonvolatile manner. A RAM that temporarily stores a program executed by the CPU, data related to the program, and other peripheral circuits are provided. The contour emphasizing unit 30 included in the control unit 15 will be described later.
The input unit 16 is connected to various operation switches provided in the projector 1, detects a user operation on the operation switch, and outputs the operation signal to the control unit 15.
In the present embodiment, a brightness adjustment switch 16a is provided as an operation switch. The brightness adjustment switch 16a is a switch for adjusting the brightness of the image projected on the projection surface. The user operates the brightness adjustment switch 16a to make the image brighter. It is possible to indicate whether to darken or how much to darken. When the adjustment switch 16a is operated and brightness adjustment is instructed, the brightness of each pixel constituting the input image data is adjusted according to the instruction content, as will be described in detail later.
The storage unit 17 includes a nonvolatile memory and stores various data.

The light source lamp driving unit 18 drives the light source lamp 10 under the control of the control unit 15.
The liquid crystal light valve drive unit 19 drives the liquid crystal light valve 11 based on the image data input from the control unit 15 under the control of the control unit 15.
The projection optical system adjustment unit 20 adjusts the position of the projection optical system 12. Specifically, the projection optical system adjustment unit 20 projects the projection optical system along a direction parallel to the light source optical axis LA representing the central axis of the light emitted from the light source lamp 10 or a direction orthogonal to the light source optical axis LA. The lens included in 12 is moved. Note that the projection optical system adjustment unit 20 may not be provided, and the position of the projection optical system 12 may be manually adjusted.
The interface unit 21 is connected to an external device such as a personal computer or an optical disk drive, and performs communication based on a communication standard with the external device under the control of the control unit 15. In the present embodiment, a video signal is input from an external device to the projector 1, and the projector 1 projects an image related to the video signal input from the external device onto a projection surface.
Next, the outline emphasizing unit 30 included in the control unit 15 will be described.

FIG. 2 is a block diagram illustrating a functional configuration of the contour emphasizing unit 30.
The function of the contour emphasizing unit 30 is realized by the cooperation of hardware and software, such as the CPU of the control unit 15 executing a program stored in the ROM.
The contour emphasis unit 30 performs contour emphasis processing on the input image data to generate contour emphasis image data. As shown in FIG. 2, the contour extraction unit 31, the brightness adjustment unit 32, and the synthesis Part 33.
The contour extraction unit 31 extracts contour portions in the input image data based on the input image data, and then generates contour enhancement data.
The contour enhancement data is data that is combined with input image data and emphasizes the contour of the input image data by adding overshoot and / or undershoot to the input image data. Data generated by executing filter processing using Laplacian filter on data.

FIG. 3 is a diagram for explaining an example of the contour emphasizing data. FIG. 3A illustrates how the luminance gradation values of pixels arranged continuously on the input image data change. FIG. 3B is a diagram schematically showing a graph in which the horizontal axis represents the pixel position and the vertical axis represents the luminance level. FIG. 3B shows the same outline enhancement data as FIG. It is the figure typically shown by the graph.
FIG. 4 is a diagram for explaining the synthesis of the input image data in FIG. 3A and the contour enhancement data in FIG. 3B. FIG. 4A shows the input image data, the contour FIG. 4B shows combined data generated by combining these image data.
As described above, the input image data is data in which the luminance of RGB color components is held as a gradation value for each pixel constituting the input image data (example: (R, G, B) = ( 233, 50, 180)), for the sake of clarity, in the following description, the term “pixel luminance gradation value” refers to the luminance of one color component of a pixel.

As is well known, when the change in luminance of the pixels continuously arranged on the input image data is in the state shown in FIG. 3A, the input image data is obtained by executing a filter process using a Laplacian filter. Is second-order differentiated, and edge enhancement data is generated such that the change in luminance is in the state shown in FIG. 3B for the portion corresponding to the pixel. The contour emphasis data generated here is combined with the input image data to add overshoot and / or undershoot to the input image data and emphasize the contour portion of the input image data.
That is, referring to FIG. 4, the combined data (FIG. 4B) generated by combining the input image data and the contour emphasizing data has an overshoot in which the brightness of the contour portion protrudes, and Undershoot is formed. And when an image is projected on a projection surface based on synthetic | combination data, the image by which the outline was emphasized will be projected by the overshoot and undershoot which were formed in synthetic | combination data.
In the above example, the contour enhancement data is data generated by executing filter processing using a Laplacian filter on the input image data. However, the contour enhancement data is not limited to this. It may be generated using an unsharp mask or generated using another sharpening filter. That is, the contour emphasis data may be data that is combined with the input image data and emphasizes the contour of the input image data by adding overshoot and / or undershoot to the input image data.

Now, referring back to FIG. 2, the brightness adjustment unit 32 included in the contour emphasizing unit 30 acquires brightness adjustment information according to the user's operation on the brightness adjustment switch 16a, and based on the acquired brightness adjustment information. The input / output gain is adjusted, and the input image data is corrected according to the adjusted input / output gain to generate adjusted image data.
Here, the brightness information is the following information. That is, as described above, the user can operate the brightness adjustment switch 16a to instruct how much the image projected on the projection surface should be brightened or how dark it should be. However, the brightness adjustment information is information indicating the instruction content. Hereinafter, a value indicating how much the image projected on the projection surface is brightened or how much the image is darkened is referred to as an “adjustment value”.

The input / output gain is a value indicating a ratio between the gradation value of the pixel in the input image data and the gradation value of the pixel in the adjustment image data generated by correcting the input image data. Is the ratio of the luminance gradation value of the pixel of the adjustment image data to the luminance gradation value of the pixel of the input image data. The brightness adjusting unit 32 generates adjusted image data by correcting the gradation value of each pixel constituting the input image data according to the ratio indicated by the input / output gain. Therefore, when the input / output gain is “1”, the ratio between the gradation value of the pixels constituting the input image data and the gradation value of the pixels constituting the adjustment image data is the same, and brightness adjustment is performed. The adjusted image data generated by the unit 32 is the same as the input image data. Further, when the input / output gain is less than “1”, the gradation value of each pixel of the adjustment image data generated by the brightness adjustment unit 32 corresponds to each pixel of the input image data according to the ratio indicated by the input / output gain. On the other hand, when the input / output gain exceeds “1”, the gradation value of each pixel of the adjustment image data generated by the brightness adjustment unit 32 is in a ratio indicated by the input / output gain. Accordingly, the gradation value of each pixel of the input image data becomes higher.
In the present embodiment, a table in which the adjustment values described above are associated with the input / output gains is stored in the storage unit 17, and the input / output gains are uniquely determined according to the adjustment values.

The synthesizing unit 33 included in the contour emphasizing unit 30 synthesizes the contour emphasizing data generated by the contour extracting unit 31 and the adjustment image data generated by the brightness adjusting unit 32 to generate contour emphasized image data. As described above, since the contour enhancement data is data for adding overshoot and / or undershoot to the input image data, the contour enhancement image data generated by the synthesis unit 33 is adjusted image data. By adding overshoot and / or undershoot to the contour portion of (the data in which the luminance gradation value of each pixel of the input image data is adjusted), the image data is enhanced.
Note that the outline-enhanced image data generated by the synthesizing unit 33 is output to the liquid crystal light valve driving unit 19 after undergoing necessary image processing such as image quality adjustment and gamma correction. The liquid crystal light valve driving unit 19 drives each of the liquid crystal light valves 11 based on the input image data, thereby projecting an image whose contour is emphasized on the projection surface.

Next, the operation of the contour emphasizing unit 30 will be described using the flowchart of FIG.
First, the contour extracting unit 31 included in the contour emphasizing unit 30 acquires input image data, extracts the contour of the acquired input image data, and generates contour emphasizing data (step SA1).
Next, the brightness adjustment unit 32 adjusts the brightness of the input image data to generate adjusted image data (step SA2).
Next, the synthesizing unit 33 synthesizes the contour emphasizing data generated by the contour emphasizing unit 30 with the adjusted image data generated by the brightness adjusting unit 32 to generate contour emphasizing image data (step SA3).

  As described above, in this embodiment, after performing the edge enhancement process (process for synthesizing the edge enhancement data) on the input image data, the brightness adjustment process according to the input / output gain (in accordance with the input / output gain). Rather than performing the process of correcting the gradation value of the pixel), the edge enhancement process is performed on the adjusted image data generated by performing the brightness adjustment process on the input image data. As a result, particularly when the input / output gain is less than 1, that is, when the user is instructed to darken the image projected on the projection surface, the following advantageous effects can be obtained compared to the conventional case. Can do.

FIG. 6A shows a change in input image data when a conventional projector performs outline enhancement processing and brightness adjustment processing using overshoot, and FIG. 6B shows this embodiment. 4 shows how input image data changes when the projector 1 according to FIG. 1 performs contour enhancement processing using overshoot and brightness adjustment processing. In the graph shown in FIG. 6, a dotted line T1 is a line segment indicating the upper limit of the luminance gradation value of the pixel.
Conventionally, when outline enhancement processing and brightness adjustment processing using overshoot are performed under a situation where the input / output gain is less than “1”, first, as shown in FIG. The contour emphasis processing is performed by adding overshoot to the pixels in the contour portion of FIG. 6 (A1) (FIG. 6 (A2)), and then the input image data subjected to the contour emphasis processing is added. On the other hand, brightness adjustment processing is performed (FIG. 6 (A3)).
In this case, since it is impossible to correct the luminance beyond the upper limit of the luminance gradation value of the pixel, it is added to the pixel of the input image data as shown in FIG. Part of the overshoot may be clipped. When a part of the overshoot is clipped in this way, the luminance gap G1 (FIG. 6 (A2)) between the pixel in the contour portion and the pixel adjacent to the contour portion decreases, and the image after contour enhancement When an image is projected on the projection surface based on the data, the sharpness that should originally be obtained cannot be obtained for the image showing the contour.

On the other hand, in the present embodiment, when the contour emphasis processing using overshoot and the brightness adjustment processing are performed under a situation where the input / output gain is less than “1”, as shown in FIG. First, the brightness adjustment processing by the brightness adjustment unit 32 is performed on the input image data (FIG. 6 (B1)) (FIG. 6 (B2)). As a result, as shown in FIG. 6B2, for the pixel corresponding to the contour portion (the pixel located at the point P1 in FIG. 6B2), the gradation value of the pixel after the brightness adjustment processing, The difference H1 from the upper limit of the luminance gradation value of the pixel is larger than the difference H2 (FIG. 6 (B1)) in the input image data before the brightness adjustment processing. Thereafter, an edge emphasis process for adding overshoot is performed on the input image data (adjusted image data) after the brightness adjustment process (FIG. 6 (B3)).
As described above, in this embodiment, since the edge enhancement process is performed after the brightness adjustment process, the difference H1 enlarged by the brightness adjustment process is used to suppress overshoot clipping compared to the conventional case. Can do. Thereby, when an image is projected on the projection surface based on the image data after the contour enhancement process, it is possible to prevent the sharpness of the image indicating the contour from being reduced as much as possible.

  Furthermore, in the present embodiment, the following effects can be achieved by performing the edge enhancement process after the brightness adjustment process.

FIG. 7 is a diagram for explaining a further effect. FIG. 7A is a diagram illustrating changes in input image data when a conventional projector performs contour enhancement processing and brightness adjustment processing using overshoot. The state of is shown. Here, as is apparent from the comparison between FIG. 7A and FIG. 6A, in FIG. 7A, overshoot clipping occurs in the edge enhancement processing using overshoot on the input image data. Not.
As described above, conventionally, in the case where the contour emphasis process using overshoot and the brightness adjustment process are performed under a situation where the input / output gain is less than “1”, first, input image data (FIG. 7 (A1 )) The contour emphasis processing is performed by adding overshoot to the pixels of the contour portion (FIG. 7A2), and then the brightness adjustment is performed on the input image data subjected to the contour emphasis processing. Processing is performed (FIG. 7 (A3)).
In this case, in the input image data after the contour enhancement process, if a luminance gap G2 (FIG. 7 (A2)) between the pixels in the contour portion and the pixels adjacent to the contour portion has occurred, the brightness adjustment processing The gap G2 is reduced to the gap G′2 (FIG. 7 (A3)). As described above, due to the reduction of the gap accompanying the brightness adjustment process, when an image is projected on the projection surface based on the image data after the contour enhancement, the sharpness that should originally be obtained for the image showing the contour is obtained. Results may not be obtained.

  On the other hand, in the present embodiment, when the contour emphasis process using overshoot and the brightness adjustment process are performed under a situation where the input / output gain is less than “1”, as shown in FIG. First, brightness adjustment processing by the brightness adjustment unit 32 is performed on the input image data (FIG. 7 (B1)) (FIG. 7 (B2)), and then contour enhancement processing is performed (FIG. 7 (B3)). ). Therefore, the situation that the gap G3 (FIG. 7 (B3)) based on the overshoot added by the contour emphasis process is reduced by the brightness adjustment process cannot occur. For this reason, it becomes possible to project an image with higher sharpness on the projection surface as compared with the conventional case.

Furthermore, in the present embodiment, the contour extraction unit 31 extracts the contour of the input image data to generate contour enhancement data, and the synthesis unit 33 adjusts the image after the brightness adjustment processing by the brightness adjustment unit 32. Outline enhancement data is synthesized by combining outline enhancement data with the data.
According to this, contour enhancement data including overshoot is generated after the contour is extracted from the input image data before the brightness adjustment unit 32 performs the adjustment to lower the brightness. For this reason, the overshoot included in the contour enhancement data is calculated based on the input image data that has not been subjected to the correction of the luminance of the pixel by the brightness adjustment, that is, not affected by the process related to the brightness adjustment. Therefore, it is possible to prevent the overshoot value from being excessively small or excessive, and maintain the appropriateness of the value.

As described above, the effect that occurs when the contour emphasis process using overshoot and the brightness adjustment process are performed under the condition where the input / output gain is less than “1” has been described. However, the input / output gain exceeds “1”. Even when the contour emphasis process using the undershoot and the brightness adjustment process are performed under the circumstances, the same effect can be obtained by performing the following operation.
That is, assuming that the input / output gain exceeds “1”, first, the brightness adjustment processing by the brightness adjustment unit 32 is performed on the input image data. At this time, the brightness adjustment unit 32 For each pixel constituting the image data, the adjusted image data is generated by increasing the luminance according to the ratio indicated by the input / output gain. Thereby, for the pixel corresponding to the contour portion of the input image data (the pixel located at the point P2 in FIG. 6B2), the gradation value of the pixel after the brightness adjustment processing and the luminance gradation of the pixel The difference from the lower limit of the value is larger than the difference in the input image data before the brightness adjustment process. Then, edge enhancement processing using undershoot is performed on the adjusted image data after brightness adjustment. In this case, undershoot clipping can be suppressed by utilizing the difference enlarged by the brightness adjustment processing, and a reduction in the sharpness of the image projected on the projection surface can be prevented.

As described above, the projector 1 according to the present embodiment adjusts the brightness of input image data to generate adjusted image data, and the adjusted image data generated by the brightness adjuster 32. The contour emphasizing process is executed on the contour emphasizing unit 30 for generating the contour emphasizing image data, and the image display unit for projecting an image on the projection plane based on the contour emphasizing image data generated by the contour emphasizing unit 30 ( A light source lamp 10, a liquid crystal light valve 11, and a projection optical system 12). Then, the contour emphasizing unit 30 performs contour emphasis processing using overshoot on the adjusted image data generated by reducing the brightness of the input image data by the brightness adjusting unit 32.
According to this, as compared with the input image data before the brightness is adjusted by the brightness adjustment unit 32, it is formed between the luminance value in each pixel and the upper limit value of the luminance gradation value. Since overshoot is added to adjusted image data having a large difference, overshoot clipping can be suitably suppressed.
Furthermore, in order to perform contour enhancement processing on input image data that has been adjusted to reduce brightness, pixels in the contour portion in the input image data after contour enhancement processing using overshoot, and pixels adjacent to the contour portion, The brightness gap can be suppressed from being reduced by the brightness adjustment, and the sharpness of the image projected on the projection surface by the image display unit can be prevented from being lowered.

In this embodiment, the contour extraction unit 31 extracts the contour of the input image data to generate contour enhancement data, and the synthesis unit 33 adjusts the image after the brightness adjustment processing by the brightness adjustment unit 32. Outline enhancement data is synthesized by combining outline enhancement data with the data.
According to this, contour enhancement data including overshoot is generated after the contour is extracted from the input image data before the brightness adjustment unit 32 performs the adjustment to lower the brightness. For this reason, the overshoot included in the contour enhancement data is calculated based on the input image data that has not been subjected to the correction of the luminance of the pixel by the brightness adjustment, that is, not affected by the process related to the brightness adjustment. Therefore, it is possible to prevent the overshoot value from being excessively small or excessive, and maintain the appropriateness of the value.

In addition, the projector 1 according to the present embodiment includes a brightness adjustment switch 16a of the input unit 16 for adjusting the input / output gain. Then, when there is an input to the brightness adjustment switch 16a to adjust the input / output gain to be reduced, the brightness adjustment unit 32 changes the input image data according to the adjustment to reduce the input / output gain based on the input. Adjusted image data is generated with reduced brightness.
According to this, when there is an input for adjusting the input / output gain to the brightness adjustment switch 16a, the reduction of the input / output gain based on the input is used to prevent overshoot clipping. it can.
In particular, conventionally, when the adjustment for lowering the input / output gain is performed based on the input for performing the adjustment for lowering the input / output gain to the brightness adjustment switch 16a, the sharpness may be lowered at the same time. However, according to the present embodiment, the sharpness can be prevented from being lowered.

Further, the projector 1 according to the present embodiment increases the brightness of the input image data indicating the image projected on the projection surface to generate the adjustment image data, and the brightness adjustment unit 32 generates the adjustment image data. A contour emphasizing unit 30 that performs contour emphasis processing using undershoot on the adjusted image data.
As a result, undershoot clipping can be suppressed and a reduction in sharpness can be prevented in the same manner as when the input / output gain is lowered.

Second Embodiment
Next, a second embodiment will be described.
FIG. 8 is a block diagram illustrating a functional configuration of the projector 1b according to the present embodiment.
In the following description, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As is clear from a comparison between FIG. 1 and FIG. 8, the projector 1 b according to the present embodiment includes an illuminance sensor 40, and the control unit 15 includes a gain adjustment unit 41.
The illuminance sensor 40 is provided in the vicinity of a projection surface such as a screen, detects the illuminance (lux: lx) of the environment where the projection surface is provided, and outputs the detected value to the control unit 15.

The gain adjustment unit 41 included in the control unit 15 automatically adjusts the input / output gain according to the detection value of the illuminance sensor 40.
More specifically, when the brightness of an image projected on the projection surface is too bright compared to the illuminance of the environment where the projection surface is provided, the viewer's eyes may be burdened. Based on this, in this embodiment, the optimal input / output gain value according to the illuminance value of the environment is obtained through prior experiments and simulations, and based on this, the detection value of the illuminance sensor 40, A table in which the input / output gain values are stored in association with each other is generated and stored in the storage unit 17.
Then, the gain adjustment unit 41 acquires the detection value of the illuminance sensor 40 at any time and refers to the table stored in the storage unit 17 to obtain the input / output gain value corresponding to the detection value of the illuminance sensor 40. Acquired and used as the current input / output gain value.

Next, the operation of the contour emphasizing unit 30 in the present embodiment will be described with reference to the flowchart of FIG.
First, the gain adjustment unit 41 acquires a detection value of the illuminance sensor 40 and refers to a table stored in the storage unit 17 to set an input / output gain value corresponding to the detection value of the illuminance sensor 40 ( Step SB1).
Next, the contour extracting unit 31 included in the contour emphasizing unit 30 acquires input image data, extracts the contour of the acquired input image data, and generates contour emphasizing data (step SB2). Next, the brightness adjustment unit 32 adjusts the brightness of the input image data to generate adjusted image data (step SB3). Next, the synthesizing unit 33 synthesizes the contour emphasizing data generated by the contour emphasizing unit 30 with the adjusted image data generated by the brightness adjusting unit 32 to generate contour emphasizing image data (step SB4).

As described above, in this embodiment, since the edge emphasis process is executed after the brightness adjustment process, the overshoot clip can be suppressed and the sharpness can be prevented from being lowered as in the first embodiment described above.
In particular, in the present embodiment, the input / output gain is automatically adjusted to an appropriate value according to the illuminance of the environment where the projection surface is provided, but in order to reduce the brightness of the image projected on the projection surface, When the input / output gain is automatically adjusted to a value lower than “1”, the overshoot clip is suppressed and the sharpness is prevented from being lowered, and the brightness of the image projected on the projection surface is reduced. As a result, user convenience is further improved. In addition, the above is the same also about the outline emphasis process using an undershoot.

As described above, the projector 1b according to this embodiment includes the illuminance sensor 40 that detects the illuminance of the environment where the projection surface is provided, and the gain adjustment that adjusts the input / output gain according to the detection value of the illuminance sensor 40. Part 41. Then, the brightness adjusting unit 32 generates adjusted image data by reducing the brightness of the input image data in accordance with the adjustment for reducing the input / output gain by the gain adjusting unit 41.
According to this, the input / output gain can be appropriately adjusted according to the illuminance of the environment in which the projection surface is provided, and overshoot clipping can be suppressed when the adjustment to reduce the input / output gain is performed.

The above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified and applied within the scope of the present invention.
For example, in the above-described embodiment, the present invention has been described by taking the image display device (projector 1) that performs the contour enhancement processing on the image data of the image projected on the projection surface as an example. The present invention can be widely applied to image display devices that perform contour emphasis processing.
Moreover, although the projector 1 mentioned above was a projector of the type which projects an image on a projection surface using the transmissive | pervious liquid crystal light valve 11, it may be a projector using a reflective liquid crystal panel, and a digital mirror It may be a DMD projector using a device. In addition to a 3LCD projector that projects a color image by three liquid crystal light valves, a projector and a color wheel that project color images by time-division displaying an image corresponding to RGB using a single liquid crystal light valve. The present invention can be applied to both the single-plate DMD projector and the 3DMD projector provided. In addition to the xenon lamp, various light sources such as an ultra-high pressure mercury lamp and an LED lamp can be used as the light source lamp 10. Moreover, the projector 1 mentioned above may be a projector of a type which is arrange | positioned at the front side of a projection surface, and projects a projection light on the front surface of a projection surface, and is arrange | positioned at the back side of a projection surface, and is a projection surface. It may be a type of projector that projects projection light on the back surface.
Further, in the present embodiment, the projector 1 includes the contour emphasizing unit 30, and the brightness enhancement processing and the contour emphasis processing are executed by the contour emphasizing unit 30 as an example. In an image supply device configured separately from the projector 1, processing similar to that performed by the contour emphasizing unit 30 is performed to generate contour enhanced image data, and the generated contour enhanced image data is used as the image processing device. It is good also as a structure supplied to a projector from. That is, the function of the contour emphasizing unit 30 may be provided in the projector 1 itself, or may be provided in an image supply apparatus that supplies image data to the projector 1.
In this embodiment, the video signal is input from the external device to the projector 1. For example, the projector 1 itself is provided with a reading device that reads an external recording medium such as an optical disk or a flash memory. A configuration may be adopted in which a video signal is acquired by reading data recorded on a recording medium by a reading device.

  DESCRIPTION OF SYMBOLS 1, 1b ... Projector (image display apparatus), 10 ... Light source lamp (image display part), 11 ... Liquid crystal light valve (image display part), 12 ... Projection optical system (image display part), 15 ... Control part, 16 ... Input unit, 16a ... adjustment switch (input unit), 18 ... light source lamp drive unit, 19 ... liquid crystal light valve drive unit, 20 ... projection optical system adjustment unit, 30 ... contour enhancement unit, 32 ... brightness adjustment unit, 40 ... Illuminance sensor, 41... Gain adjustment unit.

Claims (9)

A brightness adjustment unit that adjusts the brightness of the input image data and generates adjusted image data;
An edge emphasis unit that performs edge emphasis processing on the adjusted image data generated by the brightness adjustment unit and generates edge emphasis image data;
An image display device, comprising: an image display unit that projects an image on a projection surface based on the contour-enhanced image data generated by the contour-enhancement unit. The contour emphasizing part is
The contour enhancement process using overshoot is performed on the adjusted image data generated by reducing the brightness of the input image data by the brightness adjusting unit. Image display device. The contour emphasizing part is
Contour emphasis processing using overshoot by extracting the contour of the input image data to generate contour emphasis data including overshoot and combining the contour emphasis data with the adjusted image data The image display apparatus according to claim 2, wherein: It has an input unit for adjusting the input / output gain,
The brightness adjustment unit
When there is an input for performing an adjustment to lower the input / output gain to the input unit, the brightness of the input image data is lowered in accordance with the adjustment to lower the input / output gain based on the input. 4. The image display device according to claim 2, wherein data is generated. An illuminance sensor that detects the illuminance of the environment where the projection surface is provided, and a gain adjustment unit that adjusts the input / output gain according to the detection value of the illuminance sensor,
The brightness adjustment unit
4. The image display device according to claim 2, wherein the adjusted image data is generated by lowering the brightness of the input image data in accordance with an adjustment to reduce an input / output gain by the gain adjusting unit. 5. The contour emphasizing part is
The contour enhancement process using undershoot is performed on the adjusted image data generated by increasing the brightness of the input image data by the brightness adjusting unit. Image display device. An image supply device for supplying image data to an image display device,
A brightness adjustment unit that adjusts the brightness of the input image data and generates adjusted image data;
An image supply apparatus comprising: a contour emphasis unit that performs contour emphasis processing on the adjustment image data generated by the brightness adjustment unit and generates contour emphasis image data. Adjust the brightness of the input image data to generate adjusted image data,
An image processing method, wherein an edge emphasis process is performed on the generated adjusted image data.   A program that causes an image supply device that supplies image data to an image display device to execute the image processing method according to claim 8.

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