JP2010079064A - Image processing apparatus, display device, program and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus, display device, program and image processing method, efficiently reducing power consumption while restraining lowering of subjective luminance to prevent the degradation of image quality. <P>SOLUTION: A luminance subjective value E, which indicates observer's subjective feeling on what degree the luminance of a pixel as a remarked object drops to as compared with the luminance before conversion, is calculated from a remarked luminance Cre which is the luminance of a pixel as a remarked object from a pixel value of an input image, a peripheral luminance Bre which is the luminance of a pixel corresponding to the periphery of the pixel as the remarked object from the pixel value of the input image and a converted remarked luminance Cta and a converted peripheral luminance Bta which are converted according to the average value of luminance of the input image and a conversion parameter. Pixel value conversion is performed for all pixels of the input image according to the conversion parameter and the average value of luminance to optimize the luminance subjective value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, a display using an organic light-emitting diode (OLED) has attracted attention as a next-generation display that replaces a liquid crystal display or a plasma display. A display using such an OLED can be made thinner than a liquid crystal display or a plasma display, and is thus being used as a display device for small electronic devices such as a mobile phone and a portable music player. Moreover, since the display using OLED is self-luminous like the plasma display, high contrast can be obtained.

  By the way, a display using an OLED has a very low visibility of the screen when the environmental brightness is bright. In such a case, a display using an OLED needs to increase screen brightness in order to improve visibility. In particular, since displays using OLEDs are still under development, it is difficult to make products with high luminous efficiency. If the display cannot be performed with sufficient luminance, the visibility is deteriorated and the subjective image quality is deteriorated.

  However, in general, the power consumption of a self-luminous display such as an OLED or a plasma display is proportional to the sum of the luminance of each pixel present in the screen. That is, in such a display, the power consumption increases when the screen brightness is increased.

Therefore, Patent Document 1 discloses a technique for improving the visibility of a screen without increasing power consumption. According to Patent Literature 1, a redistribution pixel detection unit that detects pixels that satisfy a preset redistribution condition, and a floor that redistributes some of the gradation values of pixels detected as a redistribution target to surrounding pixels. And a tone value redistribution unit, which realizes enlargement of contrast difference by redistribution of gradation values so as not to increase power consumption. More specifically, the “redistribution” described in Patent Document 1 is as follows.
-The target pixel whose brightness can be reduced is specified as one.-The target whose brightness can be increased is the surrounding pixels.

  That is, according to Patent Document 1, it is possible to improve visibility by specifying a target pixel for increasing and decreasing luminance by redistributing gradation values.

JP 2008-58859 A

  However, the technique disclosed in Patent Document 1 does not necessarily suppress a decrease in the subjective brightness (luminance) of the observer, and is not a countermeasure against image quality degradation caused by the technique.

  The present invention has been made in view of the above, and an image processing device, a display device, a program, and a program capable of efficiently reducing power consumption while preventing deterioration in image quality by suppressing subjective decrease in luminance An object is to provide an image processing method.

  In order to solve the above-described problems and achieve the object, an image processing apparatus according to the present invention includes an attention luminance extraction unit that extracts attention luminance that is a luminance of a pixel as a target of interest from a pixel value of an input image, and an input image. A peripheral luminance extraction unit that extracts the peripheral luminance that is the luminance of the pixel corresponding to the periphery of the pixel of interest from the pixel value, an average luminance calculation unit that calculates the average luminance of the input image, and an external input A conversion luminance generation unit that converts the attention luminance and the peripheral luminance according to the conversion parameter and the average value of the luminance, respectively, and generates the conversion attention luminance and the conversion peripheral luminance; and the attention luminance and the peripheral luminance A luminance subjective value calculation unit for calculating a luminance subjective value from the converted attention luminance and the converted peripheral luminance, and a luminance subjective value for determining and outputting the conversion parameter that increases the luminance subjective value And an image conversion unit that performs pixel value conversion on all the pixels of the input image according to the conversion parameter that increases the subjective luminance value and the average value of the luminance. To do.

  The display device of the present invention performs pixel value conversion of an input image, and an image output unit that displays an image pixel value converted by the image processing device. And.

  Further, the program of the present invention includes a computer that extracts a target luminance extraction unit that extracts a target luminance that is a luminance of a target pixel from the pixel value of the input image, and a surrounding area of the target pixel from the pixel value of the input image. A peripheral luminance extracting unit that extracts a peripheral luminance that is a luminance of a pixel corresponding to the above, an average luminance calculating unit that calculates an average value of the luminance of the input image, a conversion parameter that is input from the outside, and an average value of the luminance Accordingly, a conversion luminance generation unit that converts the attention luminance and the peripheral luminance, respectively, to generate a conversion attention luminance and a conversion peripheral luminance, the attention luminance, the peripheral luminance, the conversion attention luminance, and the conversion peripheral luminance, A luminance subjective value calculation unit that calculates a luminance subjective value from the luminance subjective value calculation unit, a luminance subjective value determination unit that determines and outputs the conversion parameter that increases the luminance subjective value, and the luminance subjective value Accordance with the conversion parameter as increases the average value of the luminance, and wherein the to be executed as an image conversion unit for performing pixel value conversion for all the pixels of the input image.

  The image processing method of the present invention is an image processing method executed by an image processing device, and the image processing device includes a control unit and a storage unit, and is executed by the control unit. The step of extracting the target luminance, which is the luminance of the pixel of interest, from the pixel value of the input image, and the peripheral luminance extraction unit determines the luminance of the pixel corresponding to the periphery of the pixel of interest from the pixel value of the input image The step of extracting the peripheral luminance, the step of calculating the average luminance of the input image, the step of calculating the average value of the luminance of the input image, and the conversion luminance generating unit to the conversion parameter and the average value of the luminance input from the outside In response, the step of converting the attention luminance and the peripheral luminance to generate the converted attention luminance and the conversion peripheral luminance, respectively, and the luminance subjective value calculation unit includes the attention luminance, the peripheral luminance, and the conversion note. Calculating a luminance subjective value from the luminance and the converted peripheral luminance, a luminance subjective value determining unit determining and outputting the conversion parameter such that the luminance subjective value is increased, and an image converting unit, Performing a pixel value conversion on all pixels of the input image in accordance with the conversion parameter that increases the subjective luminance value and the average value of the luminance.

  According to the present invention, it is possible to provide an image processing device, a display device, a program, and an image processing method capable of efficiently reducing power consumption while suppressing deterioration in image quality by suppressing subjective reduction in luminance. , Has the effect.

  Exemplary embodiments of an image processing device, a display device, a program, and an image processing method according to the present invention will be described below in detail with reference to the drawings.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. This embodiment is an example in which a mobile terminal such as a mobile phone or a mobile music player is applied as a display device.

  FIG. 1 is a block diagram showing a schematic configuration of a display device 100 according to the first embodiment of the present invention. As illustrated in FIG. 1, the mobile terminal 200 includes a display device 100 including an image processing unit 101 that performs pixel value conversion of an input image and an image output unit 102.

  The image output unit 102 is a display using an organic light-emitting diode (OLED), and displays an image whose pixel value has been converted by the image processing unit 101.

  The image processing unit 101 includes a processing device such as an ASIC and a CPU, a ROM storing a predetermined program for controlling the operation of the image processing unit 101, and a storage device such as a RAM serving as a work area of the processing device. As shown in FIG. 2, the target luminance extraction unit 2, the peripheral luminance extraction unit 3, the average luminance calculation unit 4, and the converted luminance value generation unit are cooperated with the processing device and the program stored in the storage device. 5, the luminance subjective value calculation unit 6, the first loop processing unit 7, the second loop processing unit 8, the luminance subjective value determination unit 9, and the image conversion unit 10 are realized. . Details will be described later.

  The image processing unit 101 of the present embodiment adjusts the luminance using an effect known as the Bartlson-Breneman effect that “the luminance of the pixel of interest is affected by the luminance of the surrounding pixels”. is there. That is, in this embodiment, not only the luminance of the pixel of interest but also the luminance of the surrounding pixels are manipulated. Specifically, from the relational expression having as parameters the luminance of the pixel of interest, the luminance of the surrounding pixels, the luminance after the change of the target pixel, the luminance after the change of the surrounding pixels, and the subjective brightness. The brightness of the target object and its surroundings is appropriately changed.

  The target luminance extraction unit 2 extracts the luminance of the target pixel (hereinafter referred to as target luminance) from the pixel value of the input image and outputs the extracted luminance to the converted luminance value generation unit 5. Note that the target luminance extraction unit 2 updates the position of the target pixel (target pixel) to an adjacent position for each processing count.

  The peripheral luminance extraction unit 3 extracts the luminance of pixels corresponding to the periphery of the pixel of interest (hereinafter referred to as peripheral luminance) from the pixel value of the input image and outputs the extracted luminance to the converted luminance value generation unit 5. The peripheral luminance extraction unit 3 updates the position of the target pixel (peripheral pixel) to an adjacent position for each processing count. The “peripheral luminance” is originally treated as the luminance of the surrounding environment surrounding the observer and the observation target, but is approximated as the luminance of surrounding pixels in this technique.

  The average luminance calculation unit 4 generates a histogram from the input image, calculates an average luminance value, and outputs the average value to the converted luminance generation unit 5.

  The converted luminance generation unit 5 includes the target luminance given from the target luminance extraction unit 2, the peripheral luminance given from the peripheral luminance extraction unit 3, the average value of the luminance calculated by the average luminance calculation unit 4, and the subjective luminance determination described later. From the control signal provided from the unit 9, the converted attention luminance and the converted peripheral luminance are generated and output to the luminance subjective value calculation unit 6.

  The luminance subjective value calculation unit 6 calculates the luminance subjective value of the pixel of interest in consideration of the Bartleson Breneman effect from the converted attention luminance and the converted peripheral luminance given from the converted luminance generation unit 5. The subjective luminance value represents how much the observer perceives subjectively how much the luminance of the pixel of interest is lower than the luminance before conversion.

  The first loop processing unit 7 determines whether or not the target luminance has been processed in all gradations. The first loop processing unit 7 shifts the processing to the second loop processing unit 8 when the target luminance is processed in all gradations. The first loop processing unit 7 shifts the processing to the target luminance extraction unit 2 when the target luminance is not processed in all gradations.

  The second loop processing unit 8 determines whether or not the peripheral luminance has been processed with all gradations. The second loop processing unit 8 shifts the processing to the luminance subjective value determination unit 9 when the peripheral luminance is processed with all gradations. The second loop processing unit 8 shifts the processing to the peripheral luminance extracting unit 3 when the peripheral luminance is not processed with all gradations.

  The luminance subjective value determination unit 9 holds the sum of the luminance subjective values given from the luminance subjective value calculation unit 6 for each control signal candidate, and determines whether or not the processing has been completed for all the control signals. When the processing with all the control signals is finished, the luminance subjective value determination unit 9 outputs the control signal with the smallest sum of the luminance subjective values among all the control signals. On the other hand, the luminance subjective value determination unit 9 updates the control signal to the next control signal candidate when the processing for all the control signals is not completed, and shifts the processing to the converted luminance generation unit 5.

  The image conversion unit 10 generates and outputs an output image from the input image and the control signal given from the luminance subjective value determination unit 9.

  Next, the processing operation of each part constituting the image processing unit 101 will be described in detail.

  First, the attention luminance extraction unit 2 will be described. FIG. 3 is a flowchart showing the flow of processing in the target luminance extraction unit 2. As shown in FIG. 3, the focused luminance extraction unit 2 first updates the pixel position of the input image according to the number of executions (step S1). As a result, the target luminance extraction unit 2 can update the position of the target pixel (target pixel) to an adjacent position for each processing count. Next, the target luminance extraction unit 2 converts the target pixel value into a luminance value (step S2), and outputs the luminance value to the converted luminance generation unit 5 (step S2).

  Next, the peripheral luminance extraction unit 3 will be described. FIG. 4 is a flowchart showing the flow of processing in the peripheral luminance extraction unit 3. As shown in FIG. 4, the peripheral luminance extraction unit 3 first updates the pixel position of the input image according to the number of executions (step S11). Accordingly, the peripheral luminance extraction unit 3 can update the position of the target pixel (peripheral pixel) to an adjacent position for each processing count. Next, the peripheral luminance extraction unit 3 converts the target pixel value into a luminance value (step S12), and outputs the luminance value to the converted luminance generation unit 5 (step S13).

  Next, the average luminance calculation unit 4 will be described. FIG. 5 is a flowchart showing the flow of processing in the average luminance calculation unit 4. As shown in FIG. 5, the average luminance calculation unit 4 initializes the pixel position (step S21), and then adds it to “g_sum” representing the sum of the luminance g at a predetermined pixel position of the input image (step S22). Then, a histogram is generated (updated) (step S23). The process of steps S22 to S23 is executed by updating the pixel position. When the process of steps S22 to S23 is performed for all the pixels (Yes in step S24), “g_sum” representing the sum of the luminance g is expressed by the total number of pixels. By dividing, the average value of the luminance g is calculated (step S25) and output to the converted luminance generation unit 5 (step S26).

Next, the converted luminance generation unit 5 will be described. The converted luminance generation unit 5 basically has an attention luminance value given from the attention luminance extraction unit 2, a peripheral luminance value given from the peripheral luminance extraction unit 3, and an average value of luminances calculated by the average luminance calculation unit 4. Then, the converted attention luminance and the converted peripheral luminance are generated and output to the luminance subjective value calculation unit 6. More specifically, the converted luminance generation unit 5 calculates the converted notice luminance and the converted peripheral luminance according to Equation 1 shown below.

  In Equation 1, d is a constant determined by allowable power consumption, ave is an average value of luminance calculated by the average luminance calculation unit 4, and g (a) is input luminance.

  For example, the converted notice brightness f (a) is calculated by using the notice brightness value given from the notice brightness extraction unit 2 as g (a) and the control signal x as rate. Similarly, the converted peripheral luminance f (a) is calculated by using g (a) as the peripheral luminance value given from the peripheral luminance extracting unit 3 and rate as the control signal x.

The subjective luminance value calculation unit 6 calculates the subjective luminance value of the pixel of interest in consideration of the Bartleson Breneman effect according to Equation 2 below (how much does the observer subjectively feel how much the luminance is lower than the luminance before conversion)? Is calculated. By performing processing so that the subjective luminance value is increased, image quality deterioration can be prevented.

  However, Bre is a peripheral luminance value, Cre is a focused luminance value, Bta is a converted peripheral luminance value, and Cta is a converted focused luminance value.

Expression 2 is obtained by performing a subjective evaluation experiment based on the Bodmann Model (HWBodmann, P. Haubner and AM Marsden, Proc. CIE 19th Session. CIE Publ. No. 50, 99 (1980)).
Brightness perception = a * (luminance) ^0.31 − (b + c * (peripheral luminance) ^0.31 )
a, b, c are constants

Specifically, the subjective evaluation experiment is an experiment as shown below. FIG. 6 is an image used in this subjective evaluation experiment. This is a task to answer how the luminance of the right square patch 52 in FIG. 6 looks with respect to the left square patch 51 in FIG. The left side in FIG. 6 corresponds to before conversion, and the right side in FIG. 6 corresponds to after conversion. The subjective value is input with the slider bar 53 below. The center zero is "I don't know", the brighter it goes to the right and the darker it goes to the left. The recognition limit is within ± 0.5, and the tolerance limit is within ± 1.5. The target luminance before conversion, the target luminance after conversion, the peripheral luminance before conversion, and the peripheral luminance after conversion are randomly generated, and the task is repeated. The data thus obtained is Table 1 shown below. An approximate expression obtained by regression analysis of the result of this experiment is Expression 2.

Next, the luminance subjective value determination unit 9 will be described. The luminance subjective value determination unit 9 searches for a conversion that optimizes the luminance subjective value. That is, the luminance subjective value determination unit 9 calculates E_sum that represents the sum of the luminance subjective values E for each control signal x using Equation 3 below, and determines whether or not E_sum is a conversion parameter that maximizes the E_sum. To do.

  In Equation 3, i is a pixel value of the target luminance, j is a pixel value of the peripheral luminance, h is a weight determined by the pixel value, and is a value obtained by multiplying the number of pixels of the pixel value in the histogram by the luminance of the pixel value. The weight h uses the characteristic that the brighter the higher the attractiveness (Shoji Tanaka, Masayuki Inoue, Seiki Inoue, Ryohei Nakatsu, “ “Extraction”, Journal of the Institute of Image Information and Television Engineers, vol52, No6, pp.881-890, (1998)).

  FIG. 7 is a flowchart showing the flow of processing in the luminance subjective value determination unit 9. As shown in FIG. 7, when the luminance subjective value E calculated by the luminance subjective value calculation unit 6 is larger than the largest luminance subjective value E_best so far (Yes in step S31), E_best is set as the luminance subjective value E. After the update (step S32), it is determined whether or not the gradation is looped (step S33).

  On the other hand, if the luminance subjective value E calculated by the luminance subjective value calculating unit 6 is not larger than the largest luminance subjective value E_best so far (No in step S31), the process proceeds to step S33 as it is.

  If the control signal x is not within the allowable conversion value (No in step S33), the preset update width is added to the control signal x, the process is returned to the converted luminance generation unit 5 and the process ends (step S34).

  If the control signal x is within the allowable conversion value (Yes in step S33), the control signal x is output to the image conversion unit 10 and the process is terminated (step S35).

  In this way, the luminance subjective value determination unit 9 outputs to the image conversion unit 10 a control signal x (conversion parameter rate) that maximizes E_sum representing the total luminance subjective value E for each control signal x.

  Further, when the luminance subjective value determination unit 9 determines that the luminance subjective value E is not the optimum value, the luminance subjective value determination unit 9 updates the conversion parameter rate of the conversion luminance generation unit 5 for recalculation.

Next, the image conversion unit 10 will be described. The image conversion unit 10 uses the control signal x input from the luminance subjective value determination unit 9 as a conversion parameter rate, and performs the following processing on all pixels of the input image. The image conversion unit 10 uses the value g obtained by converting the pixel value to the luminance value, and calculates the output luminance value g ′ according to the following Expression 4.

  However, it is assumed that ave is an average value of luminance input from the average luminance calculation unit 4.

  This output luminance value g ′ is converted into a pixel value and written to the output image. These processes are performed for all the pixels, and the process ends.

  As described above, according to the present embodiment, the target luminance that is the luminance of the target pixel from the pixel value of the input image and the luminance of the pixel corresponding to the periphery of the target pixel from the pixel value of the input image. Based on a certain peripheral luminance, the conversion target luminance converted according to the average value of the luminance of the input image and the conversion parameter, and the conversion peripheral luminance, how much is the luminance of the pixel of interest compared to the luminance before conversion? Calculates the subjective luminance value indicating whether the observer feels subjectively or not, and converts the pixel value for all the pixels of the input image according to the conversion parameter that optimizes the subjective luminance value and the average luminance value. I do. By using the Bartleson Breneman effect that the brightness of the target object is affected by the surrounding brightness, the subject's subjective brightness is affected by the influence of the brightness of the pixels around the target pixel. The brightness of each pixel can be adjusted so as to increase the brightness, and not only the brightness of interest, but also the surrounding brightness can be changed appropriately. Therefore, since it is possible to suppress a subjective decrease in luminance, it is possible to efficiently reduce power consumption because physical luminance is lowered while preventing deterioration of image quality.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is also omitted.

  FIG. 8 is a block diagram illustrating a functional configuration of the image processing unit 150 according to the second embodiment of the present invention. As shown in FIG. 8, the image processing unit 150 according to the present embodiment is different from the image processing unit 101 according to the first embodiment described above in that the processing of all gradation iterations is simplified. ing.

  As shown in FIG. 8, the image processing unit 150 includes an attention luminance extraction unit 151, a peripheral luminance extraction unit 152, an average luminance calculation unit 4, a converted luminance value generation unit 5, a luminance subjective value calculation unit 6, A luminance subjective value determination unit 153 and an image conversion unit 154 are provided.

The attention luminance extraction unit 151 extracts the luminance of the pixel to be noticed (hereinafter referred to as attention luminance) and the luminance dispersion value from the pixel value of the input image, and outputs them to the converted luminance value generation unit 5. More specifically, the target luminance extraction unit 151 uses the average luminance calculated by the average luminance calculation unit 4 to calculate the variance value σ using Equation 5 shown below. In Equation 5, a is a pixel value, g is a luminance value, ave is an average value, and size is the total number of pixels in the image.

The notice luminance extraction unit 151 extracts a value obtained by adding the variance value σ calculated by Expression 5 to the average value as the notice luminance value. That is,
Attention luminance value = d * average luminance + e * luminance variance (d and e are constants)
It becomes. This is a simplified configuration with an emphasis on the characteristic that attention is paid to relatively bright parts. The constant d is determined by the allowable power consumption. Since the weight of the target pixel is 1, it is omitted.

The peripheral luminance extraction unit 152 extracts the luminance of pixels corresponding to the periphery of the pixel of interest (hereinafter referred to as peripheral luminance) from the pixel value of the input image and outputs the extracted luminance to the converted luminance value generation unit 5. Similar to the target luminance extraction unit 151, the peripheral luminance extraction unit 152 calculates the variance value σ by Expression 5, and extracts a value obtained by subtracting the variance value σ calculated by Expression 5 from the average value as the peripheral luminance value. That is,
Peripheral luminance = d * average luminance−e * luminance variance (d and e are constants)
It becomes. This is a simplified configuration with an emphasis on the characteristic that attention is paid to relatively bright parts. The constant d is determined by the allowable power consumption.

  The luminance subjective value determination unit 153 performs loop processing determination from the luminance subjective value given from the luminance subjective value calculation unit 6 and outputs a new control signal to the converted luminance generation unit 5 to repeat the processing, or the image conversion unit A control signal is output to 154.

  Here, FIG. 9 is a flowchart showing the flow of processing in the luminance subjective value determination unit 153. It is assumed that the control signal x is held internally by the subjective luminance determination unit, and the initial value of x is zero. As shown in FIG. 9, first, it is evaluated whether or not the luminance subjective value E given from the luminance subjective value calculation unit 6 is larger than a preset luminance subjective allowable value (step S41). When the luminance subjective value E is larger than the luminance subjective tolerance value (Yes in step S41), the control signal x is output to the image conversion unit 154, and the process ends (step S42).

  On the other hand, when the luminance subjective value E is smaller than the luminance subjective allowable value (No in step S41), it is evaluated whether or not the control signal x is smaller than a preset conversion allowable value (step S43). If the control signal x is larger than the allowable conversion value (No in step S43), the control signal x is output to the image conversion unit 154, and the process ends (step S42). If the control signal x is smaller than the conversion allowable value (Yes in step S43), the preset update width is added to the control signal x, and the process is returned to the converted luminance generation unit 5 to end (step S44).

The image conversion unit 154 calculates a conversion parameter rate from the control signal x input from the luminance subjective value determination unit 153 and the variance value σ input from the target luminance extraction unit 151. Calculation of the conversion parameter rate is performed according to Equation 6 shown below.

  Next, the image conversion unit 154 performs the following processing on all pixels of the input image. An output pixel value g ′ is calculated according to Equation 4 using a value g obtained by converting the pixel value into a luminance value. This g ′ is converted into a pixel value and written to the output image. These processes are performed for all the pixels, and the process ends.

  Here, the hardware configuration of the image processing apparatus 101 will be described with reference to FIG.

  As shown in FIG. 10, an image processing apparatus 1001 includes a CPU (Central Processing Unit) 101, an operation unit 1002, a display unit 1003, a ROM (Read Only Memory) 1004, a RAM (Random Access Memory) 1005, a signal input unit 1006, A storage unit 1007 is provided, and each unit is connected by a bus 1008.

  The CPU 1001 uses the predetermined area of the RAM 1005 as a work area, executes various processes in cooperation with various control programs stored in advance in the ROM 1004, and controls the operation of each unit constituting the image processing apparatus 100 in an integrated manner. Further, the CPU 1001 cooperates with a program stored in advance in the ROM 1004, as shown in FIG. 2, the notice luminance extraction unit 2, the peripheral luminance extraction unit 3, the average luminance calculation unit 4, and the converted luminance. The function generation unit 5, the luminance subjective value calculation unit 6, the first loop processing unit 7, the second loop processing unit 8, the luminance subjective value determination unit 9, and the image conversion unit 10 are realized. Shall.

  The operation unit 1002 includes various input keys and the like, receives information input from the user as an input signal, and outputs the input signal to the CPU 1001.

  The ROM 1003 stores a program for controlling the image processing apparatus 100, various setting information, and the like in a non-rewritable manner.

  The RAM 1004 is a storage unit such as an SDRAM and functions as a work area for the CPU 1001 and serves as a buffer.

  The signal input unit 1005 converts an image into an electric signal and outputs it to the CPU 101.

  The storage unit 1007 has a storage medium that can be magnetically or optically recorded, and externally through a video signal acquired via the input unit 1005, a communication unit (not shown), an I / F (interface), or the like. Data such as an input video signal is stored.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

It is a block diagram which shows schematic structure of the display apparatus concerning the 1st Embodiment of this invention. It is a block diagram which shows the function structure of an image process part. It is a flowchart which shows the flow of a process in an attention brightness extraction part. It is a flowchart which shows the flow of the process in a periphery luminance extraction part. It is a flowchart which shows the flow of the process in an average luminance calculation part. It is a front view which shows the image used for the subjective evaluation experiment. It is a flowchart which shows the flow of a process in a luminance subjective value determination part. It is a block diagram which shows the function structure of the image processing apparatus concerning the 2nd Embodiment of this invention. It is a flowchart which shows the flow of a process in a luminance subjective value determination part. It is a block diagram which shows the outline of the image process part concerning this embodiment.

Explanation of symbols

2,151 Attention luminance extraction unit 3,152 Peripheral luminance extraction unit 4 Average luminance calculation unit 5 Conversion luminance generation unit 6 Luminance subjective value calculation unit 7 First loop processing unit 8 Second loop processing unit 9,153 Luminance subjective value determination unit DESCRIPTION OF SYMBOLS 10,154 Image conversion part 100 Display apparatus 101,150 Image processing apparatus 102 Image output part

Claims (7)

A target luminance extraction unit that extracts a target luminance that is a luminance of a target pixel from the pixel value of the input image;
A peripheral luminance extraction unit that extracts a peripheral luminance that is a luminance of a pixel corresponding to the periphery of the pixel of interest from the pixel value of the input image;
An average luminance calculation unit for calculating an average luminance of the input image;
A conversion luminance generation unit that converts the attention luminance and the peripheral luminance according to a conversion parameter input from the outside and the average value of the luminance, respectively, and generates a conversion attention luminance and a conversion peripheral luminance;
A luminance subjective value calculation unit that calculates a luminance subjective value from the attention luminance, the peripheral luminance, the converted attention luminance, and the converted peripheral luminance;
A luminance subjective value determination unit that determines and outputs the conversion parameter such that the luminance subjective value increases;
An image conversion unit that performs pixel value conversion on all pixels of the input image according to the conversion parameter and the average value of the luminance such that the subjective luminance value increases;
An image processing apparatus comprising: A first loop processing unit that shifts the processing to the target luminance extraction unit when the target luminance is not processed in all gradations;
The image processing apparatus according to claim 1. A second loop processing unit that shifts the processing to the peripheral luminance extraction unit when the peripheral luminance is not processed in all gradations;
The image processing apparatus according to claim 1. The target luminance extraction unit extracts a value obtained by adding a luminance variance value to the average value of the luminance as the target luminance value,
The peripheral luminance extraction unit extracts a value obtained by subtracting a luminance variance value from the average luminance value as the peripheral luminance value,
The image conversion unit performs pixel value conversion for all pixels of the input image in consideration of the luminance dispersion value.
The image processing apparatus according to claim 1. An image processing apparatus according to any one of claims 1 to 4, which performs pixel value conversion of an input image;
An image output unit for displaying an image whose pixel value has been converted by the image processing device;
A display device comprising: Computer
A target luminance extraction unit that extracts a target luminance that is a luminance of a target pixel from the pixel value of the input image;
A peripheral luminance extraction unit that extracts a peripheral luminance that is a luminance of a pixel corresponding to the periphery of the pixel of interest from the pixel value of the input image;
An average luminance calculation unit for calculating an average luminance of the input image;
A conversion luminance generation unit that converts the attention luminance and the peripheral luminance according to a conversion parameter input from the outside and the average value of the luminance, respectively, and generates a conversion attention luminance and a conversion peripheral luminance;
A luminance subjective value calculation unit that calculates a luminance subjective value from the attention luminance, the peripheral luminance, the converted attention luminance, and the converted peripheral luminance;
A luminance subjective value determination unit that determines and outputs the conversion parameter such that the luminance subjective value increases;
An image conversion unit that performs pixel value conversion on all pixels of the input image according to the conversion parameter and the average value of the luminance such that the subjective luminance value increases;
A program characterized by being executed as An image processing method executed by an image processing apparatus, wherein the image processing apparatus includes a control unit and a storage unit, and is executed in the control unit.
A step of extracting a target luminance which is a luminance of a pixel to be focused from a pixel value of the input image;
A step of extracting a peripheral luminance that is a luminance of a pixel corresponding to the periphery of the pixel of interest from the pixel value of the input image;
An average luminance calculating unit calculating an average luminance of the input image;
A converted luminance generation unit that converts the attention luminance and the peripheral luminance according to a conversion parameter input from the outside and the average value of the luminance, and generates the converted attention luminance and the converted peripheral luminance;
A luminance subjective value calculation unit calculating a luminance subjective value from the attention luminance, the peripheral luminance, the converted attention luminance, and the converted peripheral luminance;
A luminance subjective value determination unit determining and outputting the conversion parameter such that the luminance subjective value is increased; and
An image conversion unit performing pixel value conversion on all pixels of the input image according to the conversion parameter and the average value of the luminance such that the luminance subjective value is increased;
An image processing method comprising: