Noise quantity measuring apparatus
First Claim
1. A noise quantity measuring apparatus comprising:
- a memory circuit which stores therein a video input signal corresponding to at least one frame;
a subtraction circuit which calculates differences in luminance level developed every pixel between video signals in plural arbitrary areas at a newly inputted video input signal and a video signal in the same area read from the memory circuit;
an integration circuit which adds absolute values of the luminance level differences developed every pixel in the arbitrary areas, which have been calculated by the subtraction circuit, every said arbitrary area, and outputs sums of the luminance level differences every said plural arbitrary areas;
a luminance determination circuit which compares the luminance levels of the respective pixels that constitute the video signals and a predetermined threshold value every said arbitrary areas, and outputs a detection signal to the corresponding area if even one of the luminance levels exceeds the threshold value; and
a minimum value output circuit which outputs the minimum sum of luminance level differences exclusive of the area for the detection signal outputted from the luminance determination circuit, of the sums of the luminance level differences developed every said plural arbitrary areas, which are outputted from the integration circuit.
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Accused Products
Abstract
The present invention provides a noise quantity measuring apparatus adaptable to a video input signal subjected to automatic gain control. A luminance determination circuit compares luminance levels of respective pixels constituting a video input signal VIN and a predetermined threshold value for every arbitrary area Ai. If even one of the luminance levels exceeds the threshold value, then the luminance determination circuit outputs a detection signal DET to the corresponding area Ai. Sums SUMi of luminance level differences developed every plural arbitrary areas Ai, which are outputted from an integration circuit, are supplied to a selection circuit, where they are compared with an output signal OUT. Thereafter, each smaller value is supplied to a register. The register holds the output of the selection circuit in accordance with a latch signal LAT supplied from a pulse generator. On the other hand, when the detection signal DET is outputted, the latch signal LAT outputted from the pulse generator is stopped. Thus, the sum of the luminance level differences with respect to each area having pixels whose luminance levels exceed the threshold value, is ignored and eliminated from an output signal OUT indicative of the quantity of noise.
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Citations
3 Claims
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1. A noise quantity measuring apparatus comprising:
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a memory circuit which stores therein a video input signal corresponding to at least one frame; a subtraction circuit which calculates differences in luminance level developed every pixel between video signals in plural arbitrary areas at a newly inputted video input signal and a video signal in the same area read from the memory circuit; an integration circuit which adds absolute values of the luminance level differences developed every pixel in the arbitrary areas, which have been calculated by the subtraction circuit, every said arbitrary area, and outputs sums of the luminance level differences every said plural arbitrary areas; a luminance determination circuit which compares the luminance levels of the respective pixels that constitute the video signals and a predetermined threshold value every said arbitrary areas, and outputs a detection signal to the corresponding area if even one of the luminance levels exceeds the threshold value; and a minimum value output circuit which outputs the minimum sum of luminance level differences exclusive of the area for the detection signal outputted from the luminance determination circuit, of the sums of the luminance level differences developed every said plural arbitrary areas, which are outputted from the integration circuit. - View Dependent Claims (2, 3)
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Specification