| 摘要 |
In an image coding apparatus, an image signal constituted of R, G, B components is coded in a high efficiency. The image coding apparatus is arranged by: block making means for subdividing the image to make a predetermined number of image blocks; maximum/minimum value detecting means for detecting a maximum value and a minimum value of each of the plural components which constitute the component signals in pixels within the blocks; dynamic range calculating means for calculating a dynamic range equal to a difference value between the maximum value and the minimum value of each of the plural components; block dynamic range detecting means for detecting a block dynamic range equal to a maximum value thereof from the dynamic range of each of the respective plural components; quantizing step width determining means for determining a quantizing step width used to quantize each of the plural components based upon the block dynamic range; and quantizing means for quantizing each of the plural components in accordance with the quantizing step width determined by the quantizing step width determining means.
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