# US 7,609,897 B2 · Image coder and image decoder capable of power-saving control in image compression and decompression

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- Number: US 7,609,897 B2
- Document ID: US7609897B2
- Status: Granted
- Kind: B2
- Application number: 12/099,733
- Filed: 2008-04-08
- Published: 2008-09-04
- Granted: 2009-10-27
- Earliest claimed: 2002-09-09
- Assignees: Ricoh Company, Ltd.
- Inventors: Shogo Oneda; Keiichi Suzuki; Yukio Kadowaki; Yutaka Sano; Tooru Suino; Takanori Yano; Minoru Fukuda
- Web page: https://patentgrep.com/patent/US7609897B2

## CPC

- H04N 19/184: the unit being bits, e.g. of the compressed video stream
- H04N 19/132: Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
- H04N 19/156: Availability of hardware or computational resources, e.g. encoding based on power-saving criteria
- H04N 19/17: the unit being an image region, e.g. an object
- H04N 19/18: the unit being a set of transform coefficients
- H04N 19/63: using sub-band based transform, e.g. wavelets
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An image decoder comprises a code decompression/decoding unit that decodes code data produced through compression and encoding of image data, a power supply state detection unit that detects a current state of a power supply of the image decoder, and a controller that controls the code decompression/decoding unit based on the current state of the power supply so as to reduce power consumption in performing decompression and decoding of the code data.

## Claims

### Claim 1

An image coder comprising:
an image compression/encoding unit to divide an image into a plurality of tiles through a tiling process and perform compression and encoding of the image in a hierarchical manner for each of the tiles;
a power supply state detector to detect a current state of a power supply of the image coder; and
a first mode setting unit to select a tiling processing mode in accordance with the current state of the power supply,
wherein the first mode setting unit selects an overlap tiling mode when the current state of the power supply is above a reference state and selects a non-overlap tiling processing mode when the current state of the power supply is at or below the reference state.

### Claim 2

An image coder comprising:
an image compression/encoding unit to perform compression and encoding of an image using wavelet transform for frequency transform;
a power supply state detector to detect a current state of a power supply of the image coder; and
a first mode setting unit to select a processing mode of wavelet transform in accordance with the current state of the power supply, and further comprising:
a wavelet filter, wherein the first mode setting unit selects the number of taps of the wavelet filter in accordance with the current state of the power supply.

### Claim 3 (depends on 2)

The image coder according to claim 2, wherein the first mode setting unit selects a 9-tap/7-tap filter when the current state of the power supply is above a reference state, and it selects a 5-tap/3-tap filter when the current state of the power supply is at or below the reference state.

### Claim 4 (depends on 2)

The image coder according to claim 2, wherein the first mode setting unit selects a hierarchical level of wavelet transform in accordance with the current state of the power supply.

### Claim 5 (depends on 4)

The image coder according to claim 4, wherein the first mode setting unit selects a 5-level wavelet transform when the current state of the power supply is above a reference state and selects a 3-level wavelet transform when the current state of the power supply is at or below the reference state.

### Claim 6

An image coder comprising:
image compression/encoding means for performing compression and encoding of an image using wavelet transform for frequency transform;
detection means for detecting a remaining battery level when a power supply of the image coder is a battery cell; and
first setting means for designating a rate control mode of the compression and encoding in accordance with the detected battery level,
wherein the first setting means designates a Lagragian rate control more when the remaining battery level is above a reference level designates a plain rate control mode when the detected battery level is at or below the reference level.

### Claim 7

An image coder comprising:
image compression/encoding means for dividing an image into a plurality of tiles through a tiling process and for performing compression and encoding of the image in a hierarchical manner for each of the tiles;
detection means for detecting a remaining battery level when a power supply of the image coder is a battery cell; and
first setting means for designating a tiling processing mode in accordance with the detected battery level,
wherein the first setting means designates an overlap tiling mode when the remaining battery level is above a reference level designates a non-overlap tiling processing mode when the remaining battery level is at or below the reference level.

### Claim 8

An image coder comprising:
image compression/encoding means for performing compression and encoding of an image using wavelet transform for frequency transform;
detection means for detecting a remaining battery level when a power supply of the image coder is a battery cell; and
first setting means for setting a number of taps of a wavelet filter used for the wavelet transform in accordance with the detected battery level,
wherein the first setting means designates a 9-tap/7-tap filter when the detected battery level is above a reference level designates a 5-tap/3-tap filter when the detected battery level is at or below the reference state.

### Claim 9

An image coder comprising:
image compression/encoding means for performing compression and encoding of an image using wavelet transform for frequency transform;
detection means for detecting a remaining battery level when a power supply of the image coder is a battery cell; and
first setting means for designating a hierarchical level of the wavelet transform in accordance with the detected battery level,
wherein the first setting means designates a 5-level wavelet transform when the detected battery level is above a reference state designates a 3-level wavelet transform when the detected battery level is at or below the reference level.

### Claim 10 (depends on 6)

The image coder according to claim 6, further comprising:
second setting means for designating a tiling mode or the rate control mode of the compression and encoding, regardless of the mode designated by the first setting means.