Patent EP0414505A2 successfully refreshed from Google Patents.
EP0414505A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Edge enhanced error diffusion algorithm
Assignee: Xerox Corp
•
Filing: 1990-08-21
•
Granted: —
•
Expires: 2010-08-21
Abstract
Abstract A method of dynamically adjusting the threshold level (T n ) of an error diffusion algorithm to selectively control the amount of edge enhancement introduced into the encoded output (B n ). The threshold level is selectively modified (40, 42) on a pixel by pixel basis and may be used to increase or decrease the edge enhancement of the output digital image, thus, more closely representing the original detail and edge sharpness of the continuous tone input image (I n ).
Inventors
- 👤 Reiner Eschbach
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:13
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052; H04N1/4053
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
183 words
A method of image encoding in a system for manipulating and displaying digital images represented by a plurality of pixels, each pixel having a given value, the system having a memory for digitally storing the image pixels and a screen for displaying the image as a raster of pixels having a plurality of output states, the method including the steps of: comparing (20) the given value of a first pixel (I n ) with a threshold (T n ), determining (22, 24) the output state (B n ) of said first pixel depending upon the relationship of the pixel to the output state, introducing (12, 14) the variance (E n ) of the first pixel value from the output state into the deviation of a second pixel value from the threshold to determine the output state of the second pixel, repeating the steps for each pixel of the digital image, and selectively changing (40, 42) the threshold level (T n ) during the image encoding, including analyzing the value of each pixel in order to determine if the threshold level should be changed.
Claim 2
Independent Claim
183 words
A method of image encoding in a system for manipulating and displaying digital images represented by a plurality of pixels, each pixel having a given value, the system having a memory for digitally storing the image pixels and a screen for displaying the image as a raster of pixels having a plurality of output states, the method including the steps of: comparing (20) the given value of a first pixel (I n ) with a threshold (T n ), determining (22, 24) the output state (B n ) of said first pixel depending upon the relationship of the pixel to the output state, introducing (12, 14) the variance (E n ) of the first pixel value from the output state into the deviation of a second pixel value from the threshold to determine the output state of the second pixel, repeating the steps for each pixel of the digital image, and selectively changing (40, 42) the threshold level (T n ) during the image encoding, including analyzing the value of each pixel in order to determine if the threshold level should be changed.
Claim 3
Independent Claim
186 words
A method of image encoding in a system for displaying digital images represented by a plurality of pixels, each pixel having a given value, the system having a memory for digitally storing the image pixels and a screen for displaying the image as a raster of pixels having a first and a second encoded state, the method including comparing the values of each pixel in sequence with a threshold to determine the encoded states of said pixels, and also including the steps of: determining the variance of the values of each pixel from the encoded state of said pixels, introducing the variance of each pixel value from the encoded state into the variance of each successive pixel value, and comparing the variance of the value of each pixel, including the variance of its previous pixel, to the threshold level to determine the encoded state of the pixel, and selectively changing the threshold during the image encoding, the step of selectively changing the threshold level including the step of analyzing the values of pixels within a neighborhood of pixels to determine if the threshold should be changed.
Claim 4
Independent Claim
186 words
A method of image encoding in a system for displaying digital images represented by a plurality of pixels, each pixel having a given value, the system having a memory for digitally storing the image pixels and a screen for displaying the image as a raster of pixels having a first and a second encoded state, the method including comparing the values of each pixel in sequence with a threshold to determine the encoded states of said pixels, and also including the steps of: determining the variance of the values of each pixel from the encoded state of said pixels, introducing the variance of each pixel value from the encoded state into the variance of each successive pixel value, and comparing the variance of the value of each pixel, including the variance of its previous pixel, to the threshold level to determine the encoded state of the pixel, and selectively changing the threshold during the image encoding, the step of selectively changing the threshold level including the step of analyzing the values of pixels within a neighborhood of pixels to determine if the threshold should be changed.
Claim 5
Dependent Claim
18 words
The method of claim 1 or claim 2 wherein the given values of the pixels are greyscale levels.
Claim 6
Dependent Claim
18 words
The method of claim 1 or claim 2 wherein the given values of the pixels are color values.
Claim 7
Dependent Claim
30 words
The method of claim 1 or claim 2 wherein the output states or encoded states are determined by comparison to a plurality of thresholds generating a plurality of output states.
Claim 8
Dependent Claim
52 words
The method of claim 1 or claim 2 wherein the step of introducing the variance includes the step of adding the variance of each pixel from the output state or the encoded state to the variance of each previous pixel from the output state or the encoded state of said previous pixel.
Claim 9
Independent Claim
116 words
A method of edge enhancement of a digital image in a system for manipulating digital images, represented by a plurality of pixels having greyscale levels, to provide a first and a second pixel state, the method including the steps of: comparing the greyscale level of a first pixel to a threshold level T₀ to determine a first or second state for said first pixel, analyzing the greyscale level of a second pixel, responding to the analysis of the greyscale level of the second pixel to change the threshold level to T₁, and comparing the greyscale level of the second pixel to the threshold level T₁ to determine a first or second state for said second pixel.
Claim 10
Independent Claim
116 words
A method of edge enhancement of a digital image in a system for manipulating digital images, represented by a plurality of pixels having greyscale levels, to provide a first and a second pixel state, the method including the steps of: comparing the greyscale level of a first pixel to a threshold level T₀ to determine a first or second state for said first pixel, analyzing the greyscale level of a second pixel, responding to the analysis of the greyscale level of the second pixel to change the threshold level to T₁, and comparing the greyscale level of the second pixel to the threshold level T₁ to determine a first or second state for said second pixel.
Claim 11
Independent Claim
177 words
A method of image edge enhancement in a system for manipulating and displaying digital greyscale images represented by a plurality of pixels, the system having a memory for digitally storing the greyscale image pixels and a screen for displaying the image as a raster of pixels having either a 0 or a 1 output state, the method including the steps of: determining the 0 or 1 state of a first pixel depending upon the relationship of the pixel greyscale level to the threshold level, comparing the greyscale level of said first pixel with reference to the 0 or 1 output state to determine the variance of the greyscale level from the output state, and introducing the variance of the first pixel greyscale level from the output state into the deviation of a second pixel greyscale level from the threshold level to determine the 0 or 1 state of the second greyscale pixel, wherein the improvement comprises the step of analyzing the greyscale level of each pixel in order to determine if the threshold level should be changed.
Claim 12
Independent Claim
177 words
A method of image edge enhancement in a system for manipulating and displaying digital greyscale images represented by a plurality of pixels, the system having a memory for digitally storing the greyscale image pixels and a screen for displaying the image as a raster of pixels having either a 0 or a 1 output state, the method including the steps of: determining the 0 or 1 state of a first pixel depending upon the relationship of the pixel greyscale level to the threshold level, comparing the greyscale level of said first pixel with reference to the 0 or 1 output state to determine the variance of the greyscale level from the output state, and introducing the variance of the first pixel greyscale level from the output state into the deviation of a second pixel greyscale level from the threshold level to determine the 0 or 1 state of the second greyscale pixel, wherein the improvement comprises the step of analyzing the greyscale level of each pixel in order to determine if the threshold level should be changed.
Claim 13
Dependent Claim
181 words
A technique for manipulating a digital image represented by a plurality of pixels, each of the pixels having an associated greyscale level, to provide edge enhancement of the image to be displayed as a raster of said pixels, each pixel of the raster represented by a 0 or 1 output state, including the steps of: comparing the greyscale level of a first pixel with a reference greyscale threshold level, determining the 0 or 1 output state of said first pixel depending upon the relationship of the pixel greyscale level to the threshold level, calculating the variance of the first pixel greyscale level from the output state, comparing the greyscale level of a second pixel with the reference greyscale threshold level, determining the 0 or 1 state of said second pixel depending upon the relationship of the pixel greyscale level of the second pixel to the threshold level and depending upon the variance of the first pixel greyscale level from the output state, and selectively adjusting the threshold level for selected pixels in response to the greyscale level of said selected pixels.
Claim 14
Dependent Claim
181 words
A technique for manipulating a digital image represented by a plurality of pixels, each of the pixels having an associated greyscale level, to provide edge enhancement of the image to be displayed as a raster of said pixels, each pixel of the raster represented by a 0 or 1 output state, including the steps of: comparing the greyscale level of a first pixel with a reference greyscale threshold level, determining the 0 or 1 output state of said first pixel depending upon the relationship of the pixel greyscale level to the threshold level, calculating the variance of the first pixel greyscale level from the output state, comparing the greyscale level of a second pixel with the reference greyscale threshold level, determining the 0 or 1 state of said second pixel depending upon the relationship of the pixel greyscale level of the second pixel to the threshold level and depending upon the variance of the first pixel greyscale level from the output state, and selectively adjusting the threshold level for selected pixels in response to the greyscale level of said selected pixels.
Claim 15
Dependent Claim
183 words
A technique for manipulating a digital image represented by a plurality of pixels, each of the pixels having an associated greyscale level, to provide edge enhancement of the image to be displayed as a raster of said pixels, each pixel of the raster being represented by a 0 or 1 encoded state, including the steps of: comparing the greyscale level of a first pixel with a reference greyscale threshold level, determining the 0 or 1 encoded state of said first pixel depending upon the relationship of the pixel greyscale level to the threshold level, calculating the variance of the first pixel greyscale level from the encoded state, comparing the greyscale level of a second pixel with the reference greyscale threshold level, determining the 0 or 1 encoded state of said second pixel depending upon the relationship of the pixel greyscale level of the second pixel to the threshold level and depending upon the variance of the first pixel greyscale level from the encode state, and selectively adjusting the threshold level for selected pixels in response to the greyscale level of said selected pixels.
Claim 16
Dependent Claim
183 words
A technique for manipulating a digital image represented by a plurality of pixels, each of the pixels having an associated greyscale level, to provide edge enhancement of the image to be displayed as a raster of said pixels, each pixel of the raster being represented by a 0 or 1 encoded state, including the steps of: comparing the greyscale level of a first pixel with a reference greyscale threshold level, determining the 0 or 1 encoded state of said first pixel depending upon the relationship of the pixel greyscale level to the threshold level, calculating the variance of the first pixel greyscale level from the encoded state, comparing the greyscale level of a second pixel with the reference greyscale threshold level, determining the 0 or 1 encoded state of said second pixel depending upon the relationship of the pixel greyscale level of the second pixel to the threshold level and depending upon the variance of the first pixel greyscale level from the encode state, and selectively adjusting the threshold level for selected pixels in response to the greyscale level of said selected pixels.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.