Video-based handwriting input

A video-based handwriting input method, comprising:

• capturing images including raw strokes and receiving writing sounds, when a user writes on a writing surface with a stylus having a special mark;
• extracting images of raw strokes from the captured images, wherein the captured images extracted as images of raw strokes are those images that contain the special mark on the stylus;
• and
• retrieving effective strokes from the raw strokes by utilizing the received writing sounds, wherein said retrieving includes removing raw strokes corresponding to periods in which no writing sounds are received and retaining effective strokes corresponding to periods in which writing sounds are received.

A video-based handwriting input method, comprising:

• capturing images including effective strokes and receiving writing sounds, when a user writes on a writing surface with a stylus having a special mark, said images and sounds being time-stamped;
• removing from the captured images those images corresponding to periods in which the writing sounds are not received and recording the remaining images;
• and
• retrieving effective strokes from the recorded images by comparing said recorded images with the special mark on the stylus.

A video-based handwriting input apparatus, comprising:

• a stylus having a special mark thereon;
• a camera that captures images including raw strokes of a user writing on a writing surface with the stylus;
• a microphone that receives writing sounds generated through contact of the stylus with the writing surface;
• and
• a processor that filters the captured images to extract, from the captured images, images of raw strokes that contain the special mark on the stylus and to filter out captured images that do not contain the special mark, wherein the processor retrieves effective strokes from the raw strokes by utilizing the received writing sounds.

A video-based handwriting input apparatus, comprising:

• a stylus having a special mark;
• a camera that captures images including raw strokes;
• a microphone that receives writing sounds, when a user writes on a writing surface with said stylus having a special mark;
• and
• a processor that extracts images of raw strokes by comparing the captured images with the special mark on the stylus and retrieves effective strokes from the raw strokes by utilizing the received writing sounds, wherein said processor removes raw strokes corresponding to periods in which writing sounds are not received and retains effective strokes corresponding to time periods in which writing sounds are received.

A video-based handwriting input apparatus, comprising:

• a stylus having a special mark;
• a camera that captures images including effective strokes;
• a microphone that receives writing sounds, when a user writes on a writing surface with said stylus having a special mark;
• a processor that removes captured images corresponding to periods in which no writing sounds are received and retrieves effective strokes from the captured images by comparing said captured images with the special mark on the stylus.

A program product for video-based handwriting input, comprising:

• a non-transitory computer-readable storage medium;
• and
• program code stored within the computer-readable storage medium that, when executed by a computer, causes the computer to perform:
• while a user writes on a writing surface with a stylus having thereon a special mark, capturing images including raw strokes and receiving writing sounds generated through contact of the stylus with the writing surface;
• filtering the captured images to extract, from the captured images, images of raw strokes that contain the special mark on the stylus and to filter out captured images that do not contain the special mark;
• and
• retrieving effective strokes from the raw strokes by utilizing the received writing sounds.

A program product for video-based handwriting input, comprising:

• a non-transitory computer-readable storage medium;
• and
• program code stored within the computer-readable storage medium that, when executed by a computer, causes the computer to perform:
• capturing images including effective strokes and receiving writing sounds, when a user writes on a writing surface with a stylus having a special mark, said images and sounds being time-stamped;
• removing from the captured images those images corresponding to periods in which the writing sounds are not received and recording the remaining images;
• and
• retrieving effective strokes from the recorded images by comparing said recorded images with the special mark on the stylus.