EP0105116A2
Expired / Lapsed
EP
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Enhancement of video images by selective introduction of gray-scale pels
Assignee: International Business Machines Corp
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Filing: 1983-07-29
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Granted: —
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Expires: 2003-07-29
Abstract
Abstract The present invention is a method for reducing the visual impact of stepped edges by the selective introduction of gray-scale pels before the image is displayed, in a system capable of receiving and storing non-coded binary image pel values in a direction transverse to the direction of the successive lines. The stored data is modified by assigning gray scale values to a limited number of pels on opposite sides of each identified unit step to create a string of gradually changing gray scale values extending through each identified unit step. Fixed gray scale values are assigned to any pels not previously modified to establish upper and lower limits on gray scale pel values. The displayed image is generated in accordance with the assigned gray scale pel values. The selective introduction of gray scale pels at the identified unit steps has the effect of smoothing the image in the area of the unit steps without blurring the remainder of the character.
Inventors
- 👤 Dana Alfred Lasher
- 👤 William Karl Stelzenmuller
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 20:43
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40081; G; G09; G09G; G09G5/00; G09G5/22; G09G5/24; G09G5/28
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
Method for enhancing the visual quality ot a gray scale image produced by a gray scale display device where the image is derived from data stored at a density of one bit per pel, characterized in that it comprises the steps of : a) examining the stored data to locate unit steps in binary pel values; b) assigning gray scale values to pels on opposite sides of each unit step to create a string of gradually changing pel values extending through each identified unit step; c) assigning fixed gray scale values to any pels not already modified to establish upper and lower limits on gray scale pel values; and d) generating the displayed image in accordance with the assigned gray scale pel values.
Claim 2
Dependent Claim
123 words
Method for enhancing the visual quality ot a gray scale image produced by a gray scale display device where the image is derived from data stored at a density of one bit per pel, characterized in that it comprises the steps of : a) examining the stored data to locate unit steps in binary pel values; b) assigning gray scale values to pels on opposite sides of each unit step to create a string of gradually changing pel values extending through each identified unit step; c) assigning fixed gray scale values to any pels not already modified to establish upper and lower limits on gray scale pel values; and d) generating the displayed image in accordance with the assigned gray scale pel values.
Claim 3
Dependent Claim
97 words
2 . Method according to claim 1, characterized in that : . step a includes the step of examining the stored data on a pel by pel basis along successive pel lines to identify unit steps in binary pel values in a direction transverse to the direction of the successive lines, and . step b includes the step of modifying the stored data by assigning gray scale values to a limited number of pels on opposite sides of each identified unit step to create a string of gradually changing pel values extending through each identified unit step.
Claim 4
Dependent Claim
64 words
3 . Method as defined by Claim 2 wherein binary image pel data is stored in a memory array defined by logical rows and columns corresponding to the row and column display locations of the gray scale display device and wherein substantially all stored data is examined on a pel by pel basis along successive rows to locate unit steps spanning a single row.
Claim 5
Dependent Claim
90 words
Method as defined by either of Claims 2 or 3 wherein : . step a includes the step of examining stored data in opposite directions beginning with pels adjacent each identified unit step to locate either the display boundary or the nearest pel in either the step-containing line or an adjacent line at which a change in binary pel values occurs; and . step b includes the step of assigning gray scale pel values to a predetermined maximum number of pels bounded by the starting pel and the located pel.
Claim 6
Dependent Claim
183 words
Method as defined by Claim 3, wherein : . step a includes the steps of examining the binary data biginning at column 1+1 and continuing to the right until a display boundary is encountered or a change in binary data is found in row J or in one of rows J-1 and J+1 to derive a pel distance RD, and examining the binary data beginning at column I and continuing to the left until a display boundary is encountered of rows J-1 and J+l to derive a pel distance LD; . step b includes the steps of modifying the stored data representing pels to the right of the unit step by assigning gray scale values as a function of the derived distance RD, and modifying the stored data representing pels to the left of the unit step by assigning gray scale values as a function of the derived distance LD; and . step c includes the step of assigning fixed gray scale values to any pels remaining unchanged following the modifying steps to fix upper and lower limits on gray scale pel values.
Claim 7
Dependent Claim
212 words
6 . Method as defined in Claim 5 wherein : . step a includes the step of examining binary data in a region encompassing an identifying inter-row unit step to determine whether the region also includes a second unit step extending one column from the boundary of columns I and I+1, examining the binary data beginning with the pel at the row and column immediately above the second unit step and continuing upwardly until a display boundary is encountered or a change in data is found in column I or one of columns I-1 and I+1 to derive a pel distance UD, and examining the binary data beginning with the pel at the row and column immediately below the second unit step and continuing downwardly until a display boundary is encountered or a change in binary data is found in column I or one of columns I-1 and I+1 to derive a pel distance DD; and . step b includes the steps of modifying the stored data representing pels above the second unit step by assigning gray scale values as a function of the derived distance UD, and modifying the stored data representing pels below the second unit step by assigning gray scale values as a function of the derived distance DD.
Claim 8
Dependent Claim
40 words
7 . Method as defined in Claim 6 wherein the number of pels which are modified as the result of finding a unit step are limited to a predetermined maximum value regardless of the actual magnitude of the derived distance.
Claim 9
Dependent Claim
60 words
8 . Method as defined in Claim 6 wherein the assigned gray scale values are derived in a table lookup step wherein the values are stored in arrays defined by the original binary value of the pels being modified, the number of pels to be modified and the location of each of those pels relative to the identitied unit step.
References Cited (Backward Citations)
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