Image encoding apparatus, image decoding apparatus, image encoding method, image decoding method, and medium

An image encoding apparatus comprising:

• blocking means 1 for taking as an input a target binary image to be encoded, and for obtaining a target block by dividing said target binary image into blocks each containing a plurality of pixels;
• blocking means 2 for obtaining a reference block by dividing a previously obtained reference binary image into blocks each containing a plurality of pixels;
• statistical model selecting means for selecting a statistical model from among a plurality of statistical models, based on the states of pixels surrounding a reference pixel in said reference block, said reference pixel corresponding to a target pixel in said target block;
• and
• entropy encoding means for entropy-encoding said target pixel based on said selected statistical model, and for outputting the same as encoded data.

An image encoding apparatus comprising:

• blocking means 1 for taking as an input a target binary image to be encoded, and for obtaining a target block by dividing said target binary image into blocks each containing a plurality of pixels;
• blocking means 2 for obtaining a reference block by dividing a previously obtained reference binary image into blocks each containing a plurality of pixels;
• statistical model generating means for generating a statistical model for a target pixel from said reference block;
• and
• entropy encoding means for entropy-encoding said target pixel based on said generated statistical model, and for outputting the same as encoded data.

An image encoding method comprising the steps of:

• taking as an input a target binary image to be encoded, and obtaining a target block by dividing said target binary image into blocks each containing a plurality of pixels;
• obtaining a reference block by dividing a previously obtained reference binary image into blocks each containing a plurality of pixels;
• constructing an exclusive OR block by sequentially scanning said target block and said reference block and by exclusive-ORing pixel values between said two blocks;
• and
• generating a coded sequence representative of the results of said exclusive-ORing, and outputting the same as encoded data.

An image encoding method comprising:

• blocking step 1 for taking as an input a target binary image to be encoded, and for obtaining a target block by dividing said target binary image into blocks each containing a plurality of pixels;
• blocking step 2 for obtaining a reference block by dividing a previously obtained reference binary image into blocks each containing a plurality of pixels;
• statistical model selecting step for selecting a statistical model from among a plurality of statistical models, based on the states of pixels surrounding a reference pixel in said reference block, said reference pixel corresponding to a target pixel in said target block;
• and
• entropy encoding step f or entropy-encoding said target pixel based on said selected statistical model, and for outputting the same as encoded data.

An image encoding method comprising the steps of:

• taking as an input a target binary image to be encoded, and obtaining a target block by dividing said target binary image into blocks each containing a plurality of pixels;
• obtaining a reference block by dividing a previously obtained reference binary image into blocks each containing a plurality of pixels;
• generating a statistical model for a target pixel from said reference block;
• and
• entropy-encoding said target pixel based on said generated statistical model, and outputting the same as encoded data.

An image encoding apparatus comprising:

• multi-value to binary converting means for taking a target multi-value image to be encoded and a smoothing function as inputs, and for generating a binary image from said multi-value image on the basis of said smoothing function;
• binary image encoding means for encoding said binary image, and for outputting the same as binary image encoded data;
• and
• smoothing function encoding means for encoding said smoothing function, and for outputting the same as smoothing function encoded data, and wherein:
• said smoothing function is a function so adjusted that the original multi-value image could, in effect, be reproduced if said smoothing function were applied to said binary image.

An image encoding apparatus comprising:

• smoothing function estimating means for estimating a smoothing function from a target multi-value image to be encoded;
• multi-value to binary converting means for converting said multi-value image to a binary image based on a multi-value to binary conversion criterion determined to match said estimated smoothing function;
• binary image encoding means for encoding said binary image, and for outputting the same as binary image encoded data;
• and
• smoothing function encoding means for encoding said estimated smoothing function, and for outputting the same as smoothing function encoded data.

An image encoding apparatus comprising:

• multi-value to binary converting means for generating a binary image from a target multi-value image to be encoded;
• binary image encoding means for encoding said binary image, and for outputting the same as binary image encoded data;
• smoothing function generating means for generating a smoothing function from said binary image and said target multi-value image;
• and
• smoothing function encoding means for encoding said smoothing function, and for outputting the same as smoothing function encoded data.

An image encoding apparatus comprising:

• multi-value to binary converting means for converting a multi-value image, which is a target image to be encoded, to a binary image based on a multi-value to binary conversion criterion determined to match said multi-value image;
• smoothing function estimating means for estimating a smoothing function such that the original multi-value image could, in effect, be reproduced if said smoothing function were applied to said binary image;
• binary image encoding means for encoding said binary image, and for outputting the same as binary image encoded data;
• and
• smoothing function encoding means for encoding said estimated smoothing function, and for outputting the same as smoothing function encoded data.

An image encoding method comprising the steps of:

• taking a target multi-value image to be encoded and a smoothing function as inputs, and generating a binary image from said multi-value image on the basis of said smoothing function;
• encoding said binary image, and outputting the same as binary image encoded data;
• and
• encoding said smoothing function, and outputting the same as smoothing function encoded data, and wherein:
• said smoothing function is a function so adjusted that the original multi-value image could, in effect, be reproduced if said smoothing function were applied to said binary image.

An image encoding method comprising:

• smoothing function estimating step for estimating a smoothing function from a target multi-value image to be encoded;
• multi-value to binary converting step for converting said multi-value image to a binary image based on a multi-value to binary conversion criterion determined to match said estimated smoothing function;
• binary image encoding step for encoding said binary image, and for outputting the same as binary image encoded data;
• and
• smoothing function encoding step for encoding said estimated smoothing function, and for outputting the same as smoothing function encoded data.

An image encoding method comprising:

• multi-value to binary converting step for generating a binary image from a target multi-value image to be encoded;
• binary image encoding step for encoding said binary image, and for outputting the same as binary image encoded data;
• smoothing function generating step for generating a smoothing function from said binary image and said target multi-value image;
• and
• smoothing function encoding step for encoding said smoothing function, and for outputting the same as smoothing function encoded data.

An image encoding method comprising:

• multi-value to binary converting step for converting a multi-value image, which is a target image to be encoded, to a binary image based on a multi-value to binary conversion criterion determined to match said multi-value image;
• smoothing function estimating step for estimating a smoothing function such that the original multi-value image could, in effect, be reproduced if said smoothing function were applied to said binary image;
• binary image encoding step for encoding said binary image, and for outputting the same as binary image encoded data;
• and
• smoothing function encoding step for encoding said estimated smoothing function, and for outputting the same as smoothing function encoded data.