TWI566232B - Image brightness adjustment circuit - Google Patents

Description

Image brightness adjustment circuit

The invention relates to an image adjustment circuit, in particular to an image brightness adjustment circuit.

In today's highly technologicalized society, electronic products have gradually integrated into people's home life, from televisions that provide entertainment, to game consoles, to computers used at work, or to smart phones. The dependence of these electronic products. Among them, whether it is the demand for work or the entertainment in life, display devices such as televisions, projectors, and liquid crystal displays are indispensable electronic products.

Among them, liquid crystal display is the mainstream of today's society, but the use of liquid crystal display can increase the size of the screen, but the brightness of the image will be lower than that of the TV using the cathode ray tube. However, with the image quality requirements Increasingly, many image brightness processing techniques have been developed. For an image that is too dark, the brightness of the image can be improved by appropriate image processing.

There are a variety of methods for image brightness adjustment, such as the color-maintaining adjustable contrast and brightness enhancement method of the Republic of China Patent Publication No. 200403626, please refer to the first figure, the first embodiment of the Republic of China Patent Publication No. 200403626 The contrast and brightness enhancement apparatus 100 includes a first image conversion circuit 10, a maximum value output circuit 20, a first light emission level conversion circuit 30, a second image conversion circuit 40, a second light emission level conversion circuit 50, and a level smoothing circuit. 60. The first image conversion circuit 10 receives the RGB image signal (RGB), converts the RGB signal into a YCbCr color space, and outputs the digital light level Y and the color difference information to the first light level conversion. Circuit 30. The color difference information includes two color difference components Cb and Cr. Cb represents the difference between the blue signal and the reference signal, and Cr represents the difference between the red signal and the reference signal. Therefore, the first image conversion circuit 10 converts 8-bit RGB data into 8-bit YCbCr data. The maximum value output circuit 20 receives the input RGB image signals (RGB), compares the levels of the RGB image signals with each other, and outputs the signal M1 having the largest level among the RGB image signals (RGB) to the second light level level conversion. Circuit 50.

The first light-emitting level conversion circuit 30 receives the output signal YCbCr of the first image conversion circuit 10, and outputs the obtained Y'CbCr to the second image conversion circuit 40 according to the output signal YCbCr and the first control signal CHM. That is, the first light-emitting level conversion circuit 30 reduces only the level of the light-emitting information Y in accordance with the predetermined gain C_gain.

It can be seen from the above that the device of the Republic of China Patent Publication No. 200403626 requires a first image conversion circuit 10 and a second image conversion circuit 40, and the first image conversion circuit 10 converts 8-bit RGB data into 8-bit YCbCr data. And converting the received signal into an RGB image signal, the second image conversion circuit 40 converts the received Y'CbCr into R ₁ G ₁ B ₁ and outputs it to the display device. However, this method has a lot of room for improvement in terms of circuit complexity or cost.

Therefore, in recent years, a device that can directly adjust the color value without adjusting the color value (RGB) has been developed, but generally the method of directly adjusting the brightness using the color value is directly to the complex color value (R, G, B) respectively add the same adjustment value, but if the color value (R, G, B) is (240, 150, 100), and the adjustment value is 30, the red color value R is adjusted. The value is 270, but since the upper limit of the color value is 255, the red color value R will stay at 255 after adding the adjustment value, and the green color value G and the blue color value B will continue to rise to 180 and produce brightness. The problem of supersaturation, therefore, requires an invention to solve the above problems.

In order to solve the above problems, the present invention provides a circuit for the above problems. Image brightness adjustment circuit with low complexity and cost, and can solve the problem of image brightness oversaturation.

The main object of the present invention is to provide an image brightness adjustment circuit for performing the complement operation of one of the plurality of input color values (R, G, B) to achieve the purpose of adjusting the brightness of the image without There is a problem of over-saturation of brightness.

In order to achieve the above objects and their effects, the present invention discloses an image brightness adjustment circuit including a first adjustment circuit and an addition unit. The first adjusting circuit receives the complex input color value, and performs a complement operation on one of the input color values to generate a first adjustment value; the adding unit is coupled to the first adjusting circuit, and receives the first adjusting value and The input color values are added to the input color values to generate a plurality of output color values. In order to achieve the purpose of adjusting the brightness of the image, there is no problem of over-saturation of the brightness.

10‧‧‧First adjustment circuit

101‧‧‧First choice unit

103‧‧‧ arithmetic unit

105‧‧‧First gain adjustment unit

30‧‧‧Addition unit

301‧‧‧First Adder

303‧‧‧Second adder

305‧‧‧ third adder

50‧‧‧ display panel

70‧‧‧Second adjustment circuit

701‧‧‧Second selection unit

703‧‧‧second gain adjustment unit

The first figure is a circuit block diagram of a conventional image brightness adjustment method; the second figure is a circuit block diagram of the first embodiment of the present invention; and the third figure is the first embodiment of the present invention. The relationship between the input color value and the output color value; the fourth figure is a circuit block diagram of the second embodiment of the present invention; and the fifth figure: the input color value and the output color value of the second embodiment of the present invention FIG. 6 is a diagram showing the relationship between the input color value and the output color value according to the third embodiment of the present invention; and FIG. 7(A) is a schematic diagram of the image according to the second embodiment of the present invention; Figure 7 (B) is an image histogram according to a second embodiment of the present invention; and Figure 8 (A) is a schematic diagram of the image before adjustment according to the second and third embodiments of the present invention; Figure: is a histogram of the image before adjustment according to the second and third embodiments of the present invention; ninth (A) is a schematic view of the image of the third embodiment of the present invention; and ninth (B): It is an image histogram of the third embodiment of the present invention.

For a better understanding and understanding of the structural features and the achievable effects of the present invention, please refer to the preferred embodiments and the detailed descriptions as follows: please refer to the second figure, which is A block diagram of an image brightness adjustment circuit according to a first embodiment of the present invention, as shown, the image brightness adjustment circuit of the present invention is coupled to a display panel 50 to provide a plurality of output color values (R', G', B') to The display panel 50. The image brightness adjustment circuit of the present invention comprises a first adjustment circuit 10 and an addition unit 30. The first adjustment circuit 10 receives a plurality of input color values (R, G, B) including a red input color value R, a green input color value G, and a blue input color. a value B, the first adjustment circuit 10 selects one of the input color values (R, G, B), and performs a complement operation on one of the input color values (R, G, B). In this embodiment, the first adjusting circuit 10 selects one of the maximum values of the input color values (R, G, B), and the first adjusting circuit 10 performs the maximum value of the input color values (R, G, B). After the 1's complements operation, multiplying by a first gain value G _K produces a first adjustment value X. The adding unit 30 receives the input color value (R, G, B) and the first adjustment value X, and adds the first adjustment value X to the input color value (R, G, B) respectively to generate a complex output color value (R' , G', B'), to adjust the input color values (R, G, B), and transmit the output color values (R', G', B') to the display panel 50. The output color values (R', G', B') include a red output color value R', a green output color value G', and a blue output color value B'. The display panel 50 can be any form of display panel, such as a liquid crystal display panel.

As described above, the first adjustment circuit 10 includes a first selection unit 101, an operation unit 103, and a first gain adjustment unit 105. The first selection unit 101 receives the input color values (R, G, B), and selects the maximum values of the input color values (R, G, B), and outputs the maximum value. The arithmetic unit 103 performs a complement operation of 1 on the maximum value, and outputs an operation value. For example, in the case of 8 bits, the complement operation value is obtained by (255-maximum value). The first gain adjustment unit 105 receives the operation value, and multiplies the operation value by the first gain value G _K to output the first adjustment value X. The first gain adjustment unit 105 is a multiplier, but may also be a register with a gain value, and the first gain value G _K is any number between -1 and 1.

The adding unit 30 includes a first adder 301, a second adder 303, and a third adder 305. The first adder 301 receives the red input color value R and the first adjustment value X, and adds the red input color value R to the first adjustment value X to generate a red output color value R', and the second adder 303 receives the green input. The color value G is compared with the first adjustment value X, and the green input color value G is added to the first adjustment value X to generate a green output color value G', and the third adder 305 receives the blue input color value B and the first adjustment. a value X, and the blue input color value B is added to the first adjustment value X to generate a blue output color value B', wherein the output color values (R', G', B') can also be expressed as (R+X, G+X, B+X).

Please refer to the third figure, which shows the red input color value R, the green input color value G, the blue input color value B, the first adjustment value X, and the red output of the image brightness adjustment circuit of the first embodiment of the present invention. The relationship between the color value R', the green output color value G', and the blue output color value B'. Wherein, the value 255 on the vertical axis is the upper limit of the color value. If the red input color value R is 155, the green input color value G is 95 and the blue input color value B is 35, and the first gain value G _{K is} set to 0.5. (not shown), so the maximum value of the input color values (R, G, B) is the red input color value R is 155, and then the largest of the input color values (R, G, B) After the value is subjected to a complement operation of 1, multiplied by the first gain value G _K to generate a first adjustment value X, that is, X=(255-R)*G _K , that is, X=(255-155)*0.5= 50, then adding the first adjustment value X to the input color values (R, G, B) respectively to generate the output color values (R', G', B'), that is, the red output color value R' = R+X=155+50=205, green output color value G'=G+X=95+50=145, blue output color value B'=B+X=35+50=85.

As can be seen from the above, since the first embodiment of the present invention performs the complement operation of the maximum value of the input color values (R, G, B) by 1, multiplying the first gain value G _{K to} obtain the first adjustment. The value X, and then the first adjustment value X is added to the input color value (R, G, B), respectively, wherein the complement of the maximum value of 1 is the upper limit of the color value 255 minus the maximum value, The intention is to take the maximum brightness adjustment space of the input color values (R, G, B) to avoid the problem of brightness oversaturation, and the first gain value G _K is any number between -1 and 1, therefore, The output color value (R', G', B') obtained by multiplying the maximum value after the complement operation by G _K and adding the first adjustment value X to the input color value (R, G, B) will not Exceeding the upper limit of 255, the present invention does not cause the problem of over-saturation of luminance.

Further, the arithmetic unit 103 of the present invention is not limited to performing a complement operation of one, and may perform a two-part complement operation. Therefore, any arithmetic operation performed by the arithmetic unit 103 is within the scope of the present invention.

Please refer to FIG. 4 , which is a block diagram of an image brightness adjustment circuit according to a second embodiment of the present invention. As shown in the figure, the image brightness adjustment in this embodiment is different from the first embodiment. The circuit further includes a second adjustment circuit 70. The second adjusting circuit 70 receives the input color values (R, G, B), and multiplies a minimum value of the input color values (R, G, B) by a second gain value G _W to generate a first Second, adjust the value Y.

As described above, the second adjustment circuit 70 includes a second selection unit 701 and a second gain adjustment unit 703. The second selection unit 701 receives the input color values (R, G, B), selects one of the input color values (R, G, B), and outputs the minimum value to the second gain adjustment unit 703. . The second gain adjustment unit 703 receives the minimum value, multiplies the minimum value by the second gain value G _W to generate the second adjustment value Y, and outputs the second adjustment value Y to the addition unit 30. The second gain adjustment unit 703 is a multiplier, but may also be a register with a gain value stored therein, and the second gain value G _W is an arbitrary number between -1 and 1.

Next, the first adder 301 of the adding unit 30 receives the red input color value R, the first adjustment value X and the second adjustment value Y, and inputs the red input color value R, the first adjustment value X and the second adjustment value Y. Adding a red output color value R', the second adder 303 receives the green input color value G, the first adjustment value X and the second adjustment value Y, and inputs the green input color value G, the first adjustment value X and the second The adjustment value Y is added to generate a green output color value G', and the third adder 305 receives the blue input color value B, the first adjustment value X and the second adjustment value Y, and inputs the blue color value B, the first The adjustment value X is added to the second adjustment value Y to produce a blue output color value B', and the output color value (R', G', B') can be expressed as (R+X+Y, G+X+Y) , B+X+Y).

Please refer to the fifth figure, which shows the red input color value R, the green input color value G, the blue input color value B, the first adjustment value X, and the second of the image brightness adjustment circuit of the second embodiment of the present invention. The relationship between the adjustment value Y, the red output color value R', the green output color value G', and the blue output color value B'. Wherein, the value 255 on the vertical axis is the upper limit of the color value. If the red input color value R is 155, the green input color value G is 95, the blue input color value B is 35, and the first gain value G _{K is} set to 0.5. When the second gain value G _{W is} set to -0.6 (not shown), the maximum and minimum values of the input color values (R, G, B) are respectively red input color value R is 155 and blue input. The color value B is 35. Then, after performing a 1's complement operation on the maximum value of the input color values (R, G, B), multiplying the first gain value G _K to generate a first adjustment value X, X=(255-R) *G _K , X=(255-155)*0.5=50, multiplying the minimum of the input color values (R, G, B) by the second gain value G _W and outputting a second adjustment value Y, That is, Y=B*G _W , Y=35*(-0.6)=-21, and then the first adjustment value X and the second adjustment value Y are respectively added to the input color values (R, G, B). The output color values (R', G', B') are generated, that is, the red output color value R'=R+X+Y=155+50-21=184, and the green output color value G'=G+X+ Y=95+50-21=124, blue output color value B'=B+X+=35+50-21=64.

As can be seen from the above, since the second embodiment of the present invention performs the complement operation of the maximum value of the input color values (R, G, B) by 1, multiplying the first gain value G _K to obtain the first adjustment value. X, and multiplying the minimum value of the input color values (R, G, B) by the second gain value G _W to obtain the second adjustment value Y, and then adding the first adjustment value X and the second adjustment value Y, respectively. To the input color value (R, G, B), where the complement of the maximum value is 1 is the upper limit of the color value 255 minus the maximum value, and G _K and G _{W are} between -1 and 1 Therefore, in this embodiment, G _{K is} set to a positive number, and in the case where G _{W is} set to a negative number, the first adjustment value X obtained by multiplying the maximum value after the complement operation by G _{K is} multiplied by the minimum value. The second adjustment value Y obtained by G _W , the output color value (R′, G′, B′) obtained by adding the input color value (R, G, B) must not exceed the upper limit value 255, so the present invention There is no problem with over-saturation of the brightness.

Please refer to the sixth figure, which shows the red input color value R, the green input color value G, the blue input color value B, the first adjustment value X, and the second of the image brightness adjustment circuit of the third embodiment of the present invention. The relationship between the adjustment value Y, the red output color value R', the green output color value G' and the blue output color value B', this embodiment differs from the second embodiment only in that the first gain value is used in this embodiment. G _{K is} set to -0.5, and the second gain value G _{W is} set to 0.6. Then, after performing a 1's complement operation on the maximum value of the input color values (R, G, B), multiplying the first gain value G _K to generate a first adjustment value X, X=(255-R) *G _K , X=(255-155)*(-0.5)=-50, multiplying the minimum of the input color values (R, G, B) by the second gain value G _W and outputting a second Adjusting the value Y, that is, Y=B*G _W , Y=35*0.6=21, and then adding the first adjustment value X and the second adjustment value Y to the input color values (R, G, B), respectively. The output color values (R', G', B') are generated, that is, the red output color value R'=R+X+Y=155-50+21=126, and the green output color value G'=G+X+ Y=95-50+21=66, blue output color value B'=B+X+=35-50+21=6.

As can be seen from the above, in the third embodiment, G _{K is} set to a negative number, and in the case where G _{W is} set to a positive number, the first adjustment value X obtained by multiplying the maximum value after the complement operation by G _K and the minimum value are obtained. The second adjustment value Y obtained by multiplying G _{W is} added to the output color values (R', G', B') of the input color values (R, G, B) to dim the image.

In addition, please refer to the seventh (A) to ninth (B) drawings, wherein the eighth (A) is a schematic diagram of the image before the adjustment of the image brightness adjusting circuit of the second and third embodiments of the present invention, That is, the input color value (R, G, B) is the image of (155, 95, 35), the eighth (B) chart is the corresponding image histogram, and the seventh (A), (B) is the first The image diagram and its histogram after adjustment in the second embodiment, and the ninth (A) and (B) are the image diagrams and their histograms of the third embodiment.

As shown in the seventh (A) and eighth (A) drawings, the brightening of the second embodiment of the present invention After the degree adjustment, the brightness of the seventh (A) picture is significantly higher than the eighth (A) picture, and there is no problem of over-saturation of the brightness.

As can be seen from the ninth (A) and eighth (A) diagrams, after the brightness adjustment of the third embodiment of the present invention, the brightness of the ninth (A) picture is significantly lower than the eighth (A) picture, and As can be seen from the ninth (B) and eighth (B) diagrams, after the first gain value G _{K is} set to a negative number and the second gain value G _{W is} set to a positive number by the third embodiment, The bright spot will shift to the right compared to the eighth (B) map (before adjustment), and the dark point will shift to the left as compared to the eighth (B) map (before adjustment), that is, the width of the histogram is elongated, and The contrast of the image is increased.

In summary, the image brightness adjustment circuit of the present invention obtains the first adjustment value by multiplying the maximum value of the input color values by 1 and multiplying the first gain value, and then adjusting the first adjustment value. Values are added to the input color values to achieve the purpose of brightness adjustment of the image. Since the first gain value is an arbitrary number between -1 and 1, the first adjustment value is a value obtained by performing a complement operation of 1 and multiplying by a value between -1 and 1, so that the first value is The output color value obtained by adding the adjustment value to the input color value must not exceed the upper limit of the color value. Moreover, the image brightness adjustment circuit of the present invention may further add the second adjustment value obtained by multiplying the minimum value of the input color values by the second gain value and the first adjustment value to the input color values, respectively. In order to achieve the purpose of brightness adjustment of the image. In the above manner, the image brightness adjustment circuit of the present invention can not only achieve the purpose of brightness adjustment of the image, but also solve the problem that the device for conventional brightness adjustment has over-saturation of brightness.

However, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the shapes, structures, features, and spirits described in the claims are equivalently changed. Modifications are intended to be included in the scope of the patent application of the present invention.

The invention is a novelty, progressive and available for industrial use, and should be In accordance with the requirements of patent applications stipulated in China's Patent Law, it is undoubtedly the application for invention patents in accordance with the law, and the praying office will grant patents as soon as possible.

10‧‧‧First adjustment circuit

101‧‧‧First choice unit

103‧‧‧ arithmetic unit

105‧‧‧First gain adjustment unit

30‧‧‧Addition unit

301‧‧‧First Adder

303‧‧‧Second adder

305‧‧‧ third adder

50‧‧‧ display panel

Claims (8)

An image brightness adjustment circuit, comprising: a first adjustment circuit, receiving a plurality of input color values, and performing a complement operation on a maximum value of the input color values to generate a first adjustment value; an adding unit, coupling Receiving the first adjustment circuit to receive the first adjustment value and the input color values, and adding the first adjustment value to the input color values to generate a complex output color value; and a second adjustment circuit to receive Inputting a color value, selecting a minimum value of the input color values, multiplying a gain value to generate a second adjustment value, and transmitting the second adjustment value to the adding unit, the adding unit further The two adjustment values are respectively added to the input color values to adjust the output color values; wherein, one of the first adjustment values and the second adjustment value is a positive value, and the other is a negative value. The image brightness adjustment circuit of claim 1, wherein the first adjustment circuit performs a 1's complement operation on the maximum value of the input color values. The image brightness adjustment circuit of claim 1, wherein the first adjustment circuit comprises: a first selection unit, receiving the input color values, and selecting the maximum value of the input color values for output; And an operation unit, receiving the maximum value of the input color values output by the first selection unit, and performing a complement operation on the maximum value of the input color values output by the first selection unit to generate the first An adjustment value. The image brightness adjustment circuit of claim 3, wherein the first adjustment circuit further comprises: a first gain adjustment unit, receiving the operation unit to generate an operation value, and multiplying the operation value by a gain The first adjustment value is output as a value. The image brightness adjustment circuit of claim 4, wherein the gain value of the first gain adjustment unit is any one of -1 to 1. The image brightness adjustment circuit of claim 4, wherein the first gain adjustment unit is a register or a multiplier. The image brightness adjustment circuit of claim 1, wherein the second adjustment circuit comprises: a second selection unit that receives the input color values and selects the minimum value of the input color values for output; And a second gain adjustment unit that receives the minimum value and multiplies the minimum value by the gain value to generate the second adjustment value. The image brightness adjustment circuit of claim 1, wherein the gain value is any one of -1 to 1.