US5930386A
Expired / Lapsed
US
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Image processing apparatus and method
Assignee: Canon Inc
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Filing: 1995-02-01
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Granted: 1999-07-27
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Expires: 2015-02-01
Abstract
Abstract The invention is intended to prevent deterioration in image quality of an image comprising a mixture of a natural image area, a color character image area, etc. in a process of ADCT multi-value color image compression. In the ADCT process, input image data is separated in units of different image areas based on DCT coefficients after DCT. A quantization factor and a quantization table dedicated for natural image are used for the natural image area. For the color character image area, any suitable one of several quantization factors is selected depending on magnitude of an absolute value of the DCT coefficient, and a quantization table dedicated for character is used for quantization. With this arrangement, deterioration of the color character image, particularly, difference in deterioration of characters between different colors, can be prevented.
Inventors
- 👤 Kazuhiro Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:42
CPC Classifications
H; H04; H04N; H04N11/00; H04N11/04; H04N11/042; H04N11/044; H04N1/00; H04N1/46; H04N1/64; H04N1/642; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/169; H04N19/186; H04N19/30
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
130 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a first kind of image or a second kind of image; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 2
Dependent Claim
130 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a first kind of image or a second kind of image; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 3
Dependent Claim
121 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a first kind of image or a second kind of image; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
Claim 4
Dependent Claim
121 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a first kind of image or a second kind of image; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
Claim 5
Dependent Claim
136 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a natural image or a color character image on the basis of a size of a value of the spatial frequency components; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for a natural image when the color image data represents a natural image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for a color character image when the color image data represents a color character image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 6
Dependent Claim
136 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a natural image or a color character image on the basis of a size of a value of the spatial frequency components; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for a natural image when the color image data represents a natural image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for a color character image when the color image data represents a color character image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 7
Dependent Claim
25 words
An apparatus according to claim 3, wherein said discrimination means executes the discrimination on the basis of an AC component of the spatial frequency components.
Claim 8
Dependent Claim
34 words
An apparatus according to claim 4, wherein said discrimination means executes the discrimination by comparing a sum of absolute values of AC components of the spatial frequency components with at least one threshold value.
Claim 9
Dependent Claim
45 words
An apparatus according to claim 3, wherein said apparatus further determines whether the color image data represents a color graphics image, said quantization means selecting a third quantization parameter for quantizing the spatial frequency components when the color image data represents a color graphics image.
Claim 10
Dependent Claim
127 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a natural image or a color character image on the basis of a size of a value of the spatial frequency components; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for a natural image when the color image data represents a natural image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for a color character image when the color image data represents a color character image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
Claim 11
Dependent Claim
127 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a natural image or a color character image on the basis of a size of a value of the spatial frequency components; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for a natural image when the color image data represents a natural image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for a color character image when the color image data represents a color character image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
Claim 12
Dependent Claim
144 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a first kind of image or a second kind of image on the basis of a size of a value of the spatial frequency components; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 13
Dependent Claim
144 words
An image processing apparatus comprising: generation means for generating color image data; conversion means for converting the color image data to spatial frequency components; discrimination means for discriminating whether the color image data represents a first kind of image or a second kind of image on the basis of a size of a value of the spatial frequency components; and quantization means for quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization means quantizing the spatial frequency components using the selected quantizing parameter.
Claim 14
Dependent Claim
25 words
An apparatus according to claim 8, wherein said discrimination means executes the discrimination on the basis of an AC component of the spatial frequency components.
Claim 15
Dependent Claim
34 words
An apparatus according to claim 9, wherein said discrimination means executes the discrimination by comparing a sum of absolute values of AC components of the spatial frequency components with at least one threshold value.
Claim 16
Dependent Claim
26 words
An apparatus according to claim 8, wherein the first kind of image is a character image and the second kind of image is a natural image.
Claim 17
Dependent Claim
47 words
An apparatus according to claim 8, wherein said apparatus further determines whether the color image data represents a third kind of image, said quantization means selecting a third quantization parameter for quantizing the spatial frequency components when the color image data represents the third kind of image.
Claim 18
Dependent Claim
135 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a first kind of image or a second kind of image on the basis of a size of a value of the spatial frequency components; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
Claim 19
Dependent Claim
135 words
An image processing method comprising the steps of: generating color image data; converting the color image data to spatial frequency components; discriminating whether the color image data represents a first kind of image or a second kind of image on the basis of a size of a value of the spatial frequency components; and quantizing the spatial frequency components by selecting for use a single first quantizing parameter suited for the first kind of image when the color image represents the first kind of image and by selecting one of a plurality of kinds of second parameters for use as a second quantizing parameter suited for the second kind of image when the color image data represents the second kind of image, said quantization step quantizing the spatial frequency components using the selected quantizing parameter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-07-26 | 2003-01-25 | 2003-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-07-26 | 2007-01-25 | 2007-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-07-26 | 2011-01-25 | 2011-07-27 | $7700.00 | Window Closed / Lapsed |