Apparatus and method for smoothing the lines drawn by a user at a computer
First Claim
Patent Images
1. A computer comprising:
- a freehand input device enabling a user to make a freehand input;
a display having a first resolution and capable of displaying images using at least four level greyscale;
a freehand input sensor for capturing freehand input as a binary image having an image definition at a second resolution, where the second resolution is greater that the first resolution; and
a filter system for filtering said image definition at a second resolution with a weighted convolution kernel to produce a low-pass filtered high resolution greyscale image and for sub-sampling the low-pass filtered high resolution greyscale image so as to incrementally display as an output, at the first resolution, an anti-aliased version of the freehand input.
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Abstract
A pen-based computer in which the lines drawn by a user are anti-aliased incrementally by applying a smoothing filter to the relatively high resolution pen sensor image and subsampling the result to provide a relatively low resolution image which is displayed using greyscale.
21 Citations
22 Claims
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1. A computer comprising:
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a freehand input device enabling a user to make a freehand input; a display having a first resolution and capable of displaying images using at least four level greyscale; a freehand input sensor for capturing freehand input as a binary image having an image definition at a second resolution, where the second resolution is greater that the first resolution; and a filter system for filtering said image definition at a second resolution with a weighted convolution kernel to produce a low-pass filtered high resolution greyscale image and for sub-sampling the low-pass filtered high resolution greyscale image so as to incrementally display as an output, at the first resolution, an anti-aliased version of the freehand input. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of displaying freehand input to a computer system, said system including a display having a first resolution and capable of displaying images using at least four level greyscale and further including a freehand input sensor for capturing freehand input as a binary image having an image definition at a second resolution, where the second resolution is greater than the first resolution, the method comprising the following steps:
- low-pass filtering said image definition at a second resolution with a weighted convolutional kernel to produce a filtered high resolution greyscale image; and
sub-sampling said low-pass filtered high resolution greyscale image and incrementally displaying as an output, at the first resolution, an anti-aliased version of the freehand input. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- low-pass filtering said image definition at a second resolution with a weighted convolutional kernel to produce a filtered high resolution greyscale image; and
Specification