Image encoding apparatus
AssigneeCanon Kabushiki Kaisha
InventorsHidefumi Ohsawa, Yasuhiko Yasuda, Shigeo Kato
Life of this patent
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Abstract
An image encoding apparatus includes a smoothing circuit for smoothing a binary image to be encoded, a binary-encoding circuit for binary-encoding the image smoothed by the smoothing circuit, a sampling circuit for sub-sampling the image binary-encoded by the binary-encoding circuit, and an encoding circuit for encoding the binary image sub-sampled by the sampling circuit. A degree of smoothness of an image by the smoothing circuit and a threshold value for a binary-encoding operation of the binary-encoding circuit can be varied.
Claims11
An image progressive encoding apparatus comprising:
- input means for inputting a first binary image data representing an image having a first resolution;
- generating means for generating a second binary image data representing an image having a second resolution lower than the first resolution on the basis of the first binary image data;
- and
- encoding means for encoding the first and second binary image data, respectively,
- wherein said generating means includes:
- low-pass filter means for performing low-pass filter processing on the first binary image data corresponding to a pixel of interest and surrounding pixels in accordance with a parameter;
- compare means for comparing image data obtained by the low-pass filter processing with a threshold value to form the second binary image data;
- and
- supplying means for supplying the parameter to said low-pass filter means and the threshold value to said compare means, respectively,
- wherein the threshold value to be supplied to said compare means changes in accordance with a change of the parameter of said low-pass filter means.
An image progressive encoding method comprising:
- a first step of performing low-pass filter processing on a first binary image data representing an image having a first resolution in accordance with a first parameter;
- a second step of comparing image data obtained by the low-pass filter processing of said first step with a first threshold value;
- a third step of sub-sampling image data obtained by the comparing operation of said second step to form a second binary image data representing an image having a second resolution lower than the first resolution;
- a fourth step of performing low-pass filter processing on the second binary image data formed by said third step in accordance with a second parameter;
- a fifth step of comparing image data obtained by the low-pass filter processing of said fourth step with a second threshold value;
- a sixth step of sub-sampling image data obtained by the comparing operation of said fifth step to form a third binary image data representing an image having a third resolution lower than the second resolution;
- and
- a seventh step of encoding the first, second and third binary image data, respectively,
- wherein the first and second parameters are independently set, and the first and second threshold values are independently set.
Dependencies are inferred from the claim text.