Video signal processing circuit, video display device, and video signal processing method

A video signal processing circuit which analyzes video signals inputted from outside, performs conversion processing for image quality adjustment on the video signals based on a result of analysis, transmits the video signals towards a video display unit, and generates and transmits drive control signals regarding a backlight which lights up the video display unit from a back face, the video signal processing circuit comprising:

• a feature value calculation unit which calculates a feature value that is a numerical value showing a degree of brightness of the video signals;
• and
• a gradation conversion processing unit which executes conversion processing of gradation of the video signals based on the feature value and a threshold value that is specified by the feature value, wherein
• the gradation conversion processing unit comprises:
• a gradation conversion threshold value calculation module which calculates the threshold value based on a threshold value calculation expression that is formed based on the feature value and a conversion coefficient set in advance;
• and
• a gradation conversion module which performs gradation conversion based on a linear function that increases linearly by taking a region of the gradation equal to or higher than the threshold value among the video signals as a target;
• a gradation maximum value calculation unit which calculates a maximum value of the gradation of the video signals, wherein
• the linear function that increases linearly is expressed with a gradation conversion expression that is formed based on the threshold value and the maximum value, wherein
• the gradation conversion expression is expressed as a numerical expression “output gradation=f(n)+{(f(n)−X2.2)/(MAX−Xa)}×(input gradation−MAX)”, where the maximum value is MAX, the gradation of the video signals is the input gradation, the maximum gradation (2^n−1:
• n is a gradation expression number set in advance) is f(n), the conversion coefficient is α, the gradation value when the relative luminance is α on a gamma curve of γ=2.2 is X2.2, the threshold value is Xa, and the gradation of the video signals sent out towards the video display unit is the output gradation.

A video signal processing circuit which analyzes video signals inputted from outside, performs conversion processing for image quality adjustment on the video signals based on a result of analysis, transmits the video signals towards a video display unit, and generates and transmits drive control signals regarding a backlight which lights up the video display unit from a back face, the video signal processing circuit comprising:

• a feature value calculation unit which calculates a feature value that is a numerical value showing a degree of brightness of the video signals;
• and
• a gradation conversion processing unit which executes conversion processing of gradation of the video signals based on the feature value and a threshold value that is specified by the feature value, wherein
• the gradation conversion processing unit comprises:
• a gradation conversion threshold value calculation module which calculates the threshold value based on a threshold value calculation expression that is formed based on the feature value and a conversion coefficient set in advance;
• and
• a gradation conversion module which performs gradation conversion based on a linear function that increases linearly by taking a region of the gradation equal to or higher than the threshold value among the video signals as a target, wherein
• the function that increases in a geometric series manner is expressed as a numerical expression “output gradation=(f(n)/Rank)×input gradation”, where the gradation of the video signals is the input gradation, the maximum gradation (2^n−1:
• n is a gradation expression number set in advance) is f(n), the feature value is Rank, and the gradation of the video signals sent out towards the video display unit is the output gradation.

A video signal processing which analyzes video signals inputted from outside, performs conversion processing for image quality adjustment on the video signals based on a result of analysis, transmits the video signals towards a video display unit, and generates and transmits drive control signals regarding a backlight which lights up the video display unit from a back face, the video signal processing circuit comprising:

• a feature value calculation unit which calculates a feature value that is a numerical value showing a degree of brightness of the video signals;
• and
• a gradation conversion processing unit which executes conversion processing of gradation of the video signals based on the feature value and a threshold value that is specified by the feature value, wherein
• the gradation conversion processing unit comprises:
• a gradation conversion threshold value calculation module which calculates the threshold value based on a threshold value calculation expression that is formed based on the feature value and a conversion coefficient set in advance;
• and
• a gradation conversion module which performs gradation conversion based on a linear function that increases linearly by taking a region of the gradation equal to or higher than the threshold value among the video signals as a target;
• and
• a control signal generation processing unit which generates the drive control signals showing a decrease amount of luminance of the backlight based on the feature value and transmits the generated signal towards the backlight, wherein:
• the gradation conversion module performs gradation conversion based on a function which is formed based on the decrease amount of the luminance and increases in a geometric series manner to the video signal of a smaller gradation than the threshold value among the video signals, wherein
• the function that increases in a geometric series manner is expressed as a numerical expression “output gradation=(f(n)/Rank)×input gradation”, where the gradation of the video signals is the input gradation, the maximum gradation (2^ n−1:
• n is a gradation expression number set in advance) is f(n), the feature value is Rank, and the gradation of the video signals sent out towards the video display unit is the output gradation.

A video signal processing circuit which analyzes video signals inputted from outside, performs conversion processing for image quality adjustment on the video signals based on a result of analysis, transmits the video signals towards a video display unit, and generates and transmits drive control signals regarding a backlight which lights up the video display unit from a back face, the video signal processing circuit comprising:

• a feature value calculation unit which calculates a feature value that is a numerical value showing a degree of brightness of the video signals;
• and
• a gradation conversion processing unit which executes conversion processing of gradation of the video signals based on the feature value and a threshold value that is specified by the feature value, wherein
• the gradation conversion processing unit comprises:
• a gradation conversion threshold value calculation module which calculates the threshold value based on a threshold value calculation expression that is formed based on the feature value and a conversion coefficient set in advance;
• and
• a gradation conversion module which performs gradation conversion based on a linear function that increases linearly by taking a region of the gradation equal to or higher than the threshold value among the video signals as a target, wherein
• the gradation conversion processing unit further comprises a smoothing processing module which:
• judges whether or not the gradation of the video signals belongs to a smoothing region set in advance near the threshold value;
• when judged that the gradation belongs to the smoothing region, calculates a smoothing coefficient based on a difference between the threshold value and the gradation of the video signals;
• and subtracts the smoothing coefficient from the gradation of the video signals.

A video signal processing method used in a video signal processing circuit which comprises a gradation conversion processing unit which analyzes video signals inputted from outside, performs conversion processing for image quality adjustment on the video signals based on a result of analysis, transmits the video signals towards a video display unit, and a luminance control circuit unit which generates and transmits drive control signals regarding a backlight which lights up the video display unit from a back face, the method comprising:

• calculating a feature value that is a numerical value showing a degree of brightness of the video signals by the luminance control circuit unit;
• calculating a threshold value regarding conversion of the gradation by the gradation conversion processing unit based on a threshold value calculation expression that is formed based on the feature value and a conversion coefficient set in advance;
• judging whether or not the gradation of the video signals is equal to or higher than the threshold value by the gradation conversion processing unit;
• executing gradation conversion based on a linear function that increases linearly on the video signals by the gradation conversion processing unit when judged that the gradation of the video signals is equal to or higher than the threshold value;
• judging whether or not the gradation of the video signals inputted from outside belongs to a smoothing region set in advance near the threshold value;
• calculating a smoothing coefficient based on a difference between the threshold value and the gradation of the video signals when judged that the gradation belongs to the smoothing region;
• and
• subtracting the calculated smoothing coefficient from the gradation of the video signals on which the gradation conversion is performed, wherein
• contents of each of a series of the steps are sequentially executed by the gradation conversion processing unit.