Image processing apparatus and image processing method for encoding density pattern information in attribute data

1. An image processing apparatus comprising:

an image compression conversion unit that, in an event of quantizing an image having attribute data for each pixel, creates a density pattern in which pixel values of plural pixels composing a region as a quantization target are binarized, quantizes the region based on the density pattern, and binarizes, for each pixel, the attribute data individually owned by the plural pixels composing the region; and

an image extension conversion unit that, in an event of decoding the image of the region quantized based on the density pattern by the image compression conversion unit, decides a density pattern of the region before the quantization in response to an attribute pattern that is based on the binarized attribute data of each of the plural pixels composing the region, and decodes the region in response to the decided density pattern,

wherein the image extension conversion unit decides a density pattern coinciding with the attribute pattern as the density pattern before the quantization and

wherein, based on whether or not the plural pixels have attribute data of image, the image compression conversion unit binarizes, for each pixel, the attribute data owned by the plural pixels composing the region.

2. The image processing apparatus of claim 1 ,

wherein the image compression conversion unit converts the attribute data owned by the plural pixels composing the region into first intermediate attribute data in which the attribute data is binarized for each of the pixels based on whether or not the plural pixels have the attribute data of image and into second intermediate attribute data in which the attribute data is binarized for each of the pixels based on whether or not the plural pixels have attribute data of text, and by using the first intermediate attribute data or the second intermediate attribute data, for each pixel, the attribute data owned by the plural pixels composing the region.

3. The image processing apparatus of claim 1 ,

wherein, in a case where the region is a high gradation region, the image compression conversion unit creates a density pattern in which pixel values of plural pixels composing the region are binarized, quantizes the region based on the density pattern, and binarizes, for each pixel, the attribute data individually owned by the plural pixels composing the region.

4. The image processing apparatus of claim 1 ,

wherein the image compression conversion unit quantizes the region as the quantization target by a BTC mode in a case where the region is a halftone region, and

the image extension conversion unit decodes the region, the region being quantized by the image compression conversion unit, by the BTC mode in the case where the region is a halftone region.

5. An image processing method comprising:

an image compression conversion step of, in an event of quantizing an image having attribute data for each pixel, creating a density pattern in which pixel values of plural pixels composing a region as a quantization target are binarized, quantizing the region based on the density pattern, and binarizing, for each pixel, the attribute data individually owned by the plural pixels composing the region; and

an image extension conversion step of, in an event of decoding the image of the region quantized based on the density pattern by the image compression conversion step, deciding a density pattern of the region before the quantization in response to an attribute pattern that is based on the binarized attribute data of each of the plural pixels composing the region, and decoding the region in response to the decided density pattern,

wherein, in the image extension conversion step, a density pattern coinciding with the attribute pattern is decided as a density pattern before the quantization and

wherein, in the image compression conversion step, for each pixel, the attribute data owned by the plural pixels composing the region is binarized based on whether or not the plural pixels have attribute data of image.

6. The image processing method of claim 5 ,

wherein, in the image compression conversion step, the attribute data owned by the plural pixels composing the region is converted into first intermediate attribute data in which the attribute data is binarized for each of the pixels based on whether or not the plural pixels have the attribute data of image and into second intermediate attribute data in which the attribute data is binarized for each of the pixels based on whether or not the plural pixels have attribute data of text, and by using the first intermediate attribute data or the second intermediate attribute data, the attribute data owned by the plural pixels composing the region is binarized for each pixel.

7. The image processing method of claim 5 ,

wherein, in a case where the region is a high gradation region, then in the image compression conversion step, a density pattern in which pixel values of plural pixels composing the region are binarized is created, the region is quantized based on the density pattern, and for each pixel, the attribute data individually owned by the plural pixels composing the region is binarized.

8. The image processing method of claim 5 ,

wherein, in the image compression conversion step, the region as the quantization target is quantized by a BTC mode in a case where the region is a halftone region, and

in the image extension conversion step, the region quantized by the image compression conversion step is decoded by the BTC mode in the case where the region is a halftone region.