Image coder and image decoder capable of power-saving control in image compression and decompression

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.

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.

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.

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.

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.