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US 7,689,050 B2Granted
Image processing apparatus and method with a histogram of the extracted DC components
AssigneeCanon Kabushiki Kaisha
InventorTsutomu Sakaue
Life of this patent
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Abstract
An image processing apparatus extracts DC components of an image, generates a histogram of the extracted DC components, and detects a background level of the image based on the histogram.
Claims17
An image processing apparatus comprising:
- an extractor, arranged to extract DC components of an image;
- a calculator arranged to calculate code amounts of encoded data generated upon encoding the image;
- a generator, arranged to generate a histogram of the DC components extracted by said extractor;
- and
- a detector, arranged to detect a background level of the image based on the histogram,
- wherein said generator generates said histogram of DC components from DC components which have corresponding code amounts calculated by said calculator not more than a predetermined amount.
3 more elements
An image processing apparatus comprising:
- an encoder, arranged to encode an image by computing orthogonal transforms of respective image blocks each including a predetermined number of pixels;
- a calculator arranged to calculate code amounts of encoded data output from said encoder;
- a generator, arranged to generate a histogram based on direct-current components of orthogonal transform coefficients of the image blocks;
- and
- a detector, arranged to detect a background level of the image based on the histogram,
- wherein said generator generates said histogram based on the direct-current components of the orthogonal transform coefficients of the image blocks which have code amounts not more than a predetermined amount.
3 more elements
An image processing method comprising the steps of:
- using an image processing apparatus to perform steps including:
- extracting DC components of an image;
- calculating code amounts of encoded data generated upon encoding the image;
- generating a histogram of the extracted DC components;
- and
- detecting a background level of the image based on the histogram,
- wherein the generating step includes a step of generating the histogram of DC components which have corresponding code amounts calculated in the calculating step not more than a predetermined amount.
4 more elements
An image processing method comprising the steps of:
- using an image processing apparatus to perform steps including:
- encoding an image by computing orthogonal transforms of respective image blocks each including a predetermined number of pixels;
- calculating code amounts of encoded data output in the encoding step;
- generating a histogram based on direct-current components of orthogonal transform coefficients of the image blocks;
- and
- detecting a background level of the image based on the histogram,
- wherein the generating step includes a step of generating the histogram based on the direct-current components of the orthogonal transform coefficients of the image blocks which have code amounts not more than a predetermined amount.
4 more elements
A computer-readable storage medium storing a computer-executable program for causing a computer to perform an image processing method, said method comprising the steps of:
- extracting DC components of an image;
- calculating code amounts of encoded data generated upon encoding the image;
- generating a histogram of the extracted DC components;
- and
- detecting a background level of the image based on the histogram,
- wherein the generating step includes a step of generating the histogram of DC components which have corresponding code amounts calculated in the calculating step not more than a predetermined amount.
3 more elements
A computer-readable storage medium storing a computer-executable program for causing a computer to perform an image processing method, said method comprising the steps of:
- encoding an image by computing orthogonal transforms of respective image blocks each including a predetermined number of pixels;
- calculating code amounts of encoded data output in the encoding step;
- generating a histogram based on direct-current components of orthogonal transform coefficients of the image blocks;
- and
- detecting a background level of the image based on the histogram,
- wherein the generating step includes a step of generating the histogram based on the direct-current components of the orthogonal transform coefficients of the image blocks which have code amounts not more than a predetermined amount.
3 more elements
Dependencies are inferred from the claim text.