Image encoding apparatus and method, image decoding apparatus, and non-transitory computer readable medium

An image decoding apparatus comprising:

• an input unit that receives, as an input, encoded image data;
• an input unit that receives, as an input, additional code data;
• a cut-out unit that cuts out number-of-bit data and error data included in the encoded image data;
• a prediction error value decoder that decodes the number-of-bit data, decodes the error data by using the number-of-bit data, and calculates a prediction error value;
• an additional error value decoder that decodes additional error data included in the additional code data by using the number-of-bit data, and calculates an additional error value;
• a first pixel value calculating unit that calculates a pixel value with a relatively low image quality of a pixel of interest by using the prediction error value;
• and
• a second pixel value calculating unit that calculates a pixel value with a relatively high image quality of the pixel of interest by using the additional error value.

An image decoding apparatus comprising:

• an input unit that receives, as an input, encoded image data;
• an input unit that receives, as an input, quantized image data with a relatively low image quality;
• an input unit that receives, as an input, additional code data;
• a cut-out unit that cuts out number-of-bit data included in the encoded image data;
• a decoder that decodes the number-of-bit data;
• an additional error value decoder that decodes additional error data included in the additional code data by using the number-of-bit data, and calculates an additional error value;
• and
• a pixel value calculating unit that calculates a pixel value with a relatively high image quality of a pixel of interest by using the quantized image data and the additional error value.

An image decoding apparatus comprising:

• an input unit that receives, as an input, quantized image data with a relatively low image quality;
• an input unit that receives, as an input, additional code data;
• an input unit that receives, as an input, maximum-number-of-bit data;
• an additional error value decoder that decodes additional error data included in the additional code data by using the maximum-number-of-bit data, and calculates an additional error value;
• and
• a pixel value calculating unit that calculates a pixel value with a relatively high image quality of a pixel of interest by using the quantized image data and the additional error value.

An image decoding apparatus comprising:

• an input unit that receives, as an input, quantized image data with a relatively low image quality;
• an input unit that receives, as an input, additional code data;
• a prediction error calculating unit that calculates a predicted pixel value of a pixel of interest serving as a target to be processed in the quantized image data, and calculates a prediction error value by using an actual pixel value and the predicted pixel value of the pixel of interest;
• a calculating unit that calculates a maximum number of bits by using the prediction error value;
• an additional error value decoder that decodes additional error data included in the additional code data by using the maximum number of bits, and calculates an additional error value;
• and
• a pixel value calculating unit that calculates a pixel value with a relatively high image quality of the pixel of interest by using the quantized image data and the additional error value.

A non-transitory computer readable medium storing a program causing a computer to execute a process, the process comprising:

• inputting image data to the computer;
• calculating a predicted pixel value of a pixel of interest serving as a target to be processed in the image data;
• calculating a prediction error value by using an actual pixel value and the predicted pixel value of the pixel of interest;
• encoding the prediction error value with information including a number of bits and an error value, in which only one or more most significant bits corresponding to a number of effective bits are encoded as the error value when the number of bits exceeds the number of effective bits;
• and
• encoding one or more least significant bits of the prediction error value, excluding the one or more most significant bits corresponding to the number of effective bits, as an additional error value.

An image encoding apparatus comprising:

• inputting image data to the computer;
• calculating a predicted pixel value of a pixel of interest serving as a target to be processed in the image data;
• calculating a prediction error value by using an actual pixel value and the predicted pixel value of the pixel of interest;
• encoding the prediction error value with information including a number of bits and an error value, in which only one or more most significant bits corresponding to a number of effective bits are encoded as the error value when the number of bits exceeds the number of effective bits;
• and
• encoding one or more least significant bits of the prediction error value, excluding the one or more most significant bits corresponding to the number of effective bits, as an additional error value.