Gradation converting device, gradation converting method, and computer program
First Claim
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1. A gradation converting device that converts gradation of an image, the gradation converting device comprising:
- dither means for applying dither to the image by adding random noise to a pixel value forming the image; and
one-dimensional Δ
Σ
modulation means for applying one-dimensional Δ
Σ
modulation to the image applied with the dither,wherein the dither means has an HPF (High Pass Filter) for filtering a signal, filters the random noise with the HPF, and adds high-frequency components of the random noise obtained as a result of the filtering to the pixel value.
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Abstract
A gradation converting device that converts gradation of an image includes: a dither unit that applies dither to the image by adding random noise to a pixel value forming the image; and a one-dimensional ΔΣ modulation unit that applies one-dimensional ΔΣ modulation to the image applied with the dither.
14 Citations
14 Claims
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1. A gradation converting device that converts gradation of an image, the gradation converting device comprising:
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dither means for applying dither to the image by adding random noise to a pixel value forming the image; and one-dimensional Δ
Σ
modulation means for applying one-dimensional Δ
Σ
modulation to the image applied with the dither,wherein the dither means has an HPF (High Pass Filter) for filtering a signal, filters the random noise with the HPF, and adds high-frequency components of the random noise obtained as a result of the filtering to the pixel value. - View Dependent Claims (2, 3, 4, 5)
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6. A gradation converting device that converts gradation of an image, the gradation converting device comprising:
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dither means for applying dither to the image by adding random noise to a pixel value forming the image; and one-dimensional Δ
Σ
modulation means for applying one-dimensional Δ
Σ
modulation to the image applied with the dither,wherein the one-dimensional Δ
Σ
modulation means includes;a one-dimensional filter for filtering a quantization error; arithmetic means for adding up a pixel value of the image applied with the dither and an output of the one-dimensional filter; and quantizing means for quantizing an output of the arithmetic means and outputting a quantized value including the quantization error as a result of the one-dimensional Δ
Σ
modulation, anda filter coefficient of the one-dimensional filter is determined such that high-frequency characteristics of amplitude characteristics of noise shaping performed by the one-dimensional Δ
Σ
modulation means are opposite characteristics of spatial frequency characteristics of a human vision. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A gradation converting method for a gradation converting device that converts gradation of an image, the gradation converting method comprising the steps of:
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applying dither, by use of the gradation converting device, to the image by adding random noise to a pixel value forming the image; and applying one-dimensional Δ
Σ
modulation, by use of the gradation converting device, to the image applied with the dither,wherein the gradation converting device has an HPF (High Pass Filter) for filtering a signal, and further comprising filtering the random noise with the HPF, and adding high-frequency components of the random noise obtained as a result of the filtering to the pixel value.
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13. A non-transitory computer readable medium having stored thereon a computer program for causing a computer to function as a gradation converting device that converts gradation of an image, the computer program causing the computer to function as:
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dither means for applying dither to the image by adding random noise to a pixel value forming the image; and one-dimensional Δ
Σ
modulation means for applying one-dimensional Δ
Σ
modulation to the image applied with the dither,wherein the dither means has an HPF (High Pass Filter) for filtering a signal, filters the random noise with the HPF, and adds high-frequency components of the random noise obtained as a result of the filtering to the pixel value.
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14. A gradation converting device that converts gradation of an image, the gradation converting device comprising:
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a dither unit applying dither to the image by adding random noise to a pixel value forming the image; and a one-dimensional Δ
Σ
modulation unit applying one-dimensional Δ
Σ
modulation to the image applied with the dither,wherein the dither unit has an HPF (High Pass Filter) for filtering a signal, filters the random noise with the HPF, and adds high-frequency components of the random noise obtained as a result of the filtering to the pixel value.
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Specification