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EP1111906A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

A method for enhancing the edge contrast of a digital image independently from the texture

Assignee: Eastman Kodak Co
•
Filing: 2000-12-11
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Granted: —
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Expires: 2020-12-11
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Abstract

Abstract A method is described for enhancing a digital image channel, particularly where the digital image channel is split into pedestal and texture signals that substantially comprise the digital image channel. The method utilizes a predetermined tone scale conversion to enhance the digital image channel. Initially, image values are provided from the pedestal signal corresponding to image pixels from a region of the image. Then, a statistical characteristic of the image pixels in the region is identified, and the predetermined tone scale conversion is normalized for the statistical characteristic in order to generate a normalized tone scale conversion. The normalized tone scale conversion is then performed on a central pixel of the region in order to generate a pedestal signal with enhanced image values; and the pedestal signal with enhanced image values is combined with the texture signal to generate an enhanced digital image channel.

Inventors

  • 👤 Andrew C. Gallagher
  • 👤 Edward B. Gindele

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 13:31
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/409; H04N1/4092; H04N1/46; H04N1/56; H04N1/58

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 163 words
A method for enhancing a digital image channel comprised of a plurality of image pixels, said method comprising the steps of: (a) splitting the digital image channel into first and second signals that substantially comprise the digital image channel, said first and second signals each characterized by image values corresponding to the image pixels; (b) providing a predetermined tone scale conversion to enhance the digital image channel; (c) providing image values from the first signal corresponding to image pixels from a region of the image: (d) identifying a statistical characteristic of the image pixels in the region; (e) normalizing the predetermined tone scale conversion for the statistical characteristic in order to generate a normalized tone scale conversion; (f) performing the normalized tone scale conversion on a central pixel of the region in order to generate a first signal with enhanced image values; and (g) combining the first signal with enhanced image values and the second signal to generate an enhanced digital image channel.
Claim 2
Dependent Claim 24 words
The method of claim 1 in which the first signal is a low pass signal and the second signal is a high pass signal.
Claim 3
Dependent Claim 38 words
The method of claim 1 in which the first signal is a pedestal signal characteristic of edges in the digital image channel and the second signal is a texture signal characteristic of texture in the digital image channel.
Claim 4
Dependent Claim 20 words
The method of claim 1 in which the second signal is modified before it is combined with the first signal.
Claim 5
Dependent Claim 26 words
The method of claim 1 in which the region of step (c) comprises providing image pixels from a two dimensional region distributed around the central pixel.
Claim 6
Dependent Claim 17 words
The method of claim 1 in which step (d) comprises determining a gradient value within the region.
Claim 7
Dependent Claim 22 words
The method of claim 6 in which the gradient value is derived from a maximum and a minimum value for the region.
Claim 8
Dependent Claim 27 words
The method of claim 7 in which the gradient value is computed from the difference between maximum and minimum image values of image pixels within the region.
Claim 9
Dependent Claim 32 words
The method of claim 6 in which the gradient value is computed from the difference between average maximum and minimum values across respective pluralities of image pixels comprising portions of the region.
Claim 10
Dependent Claim 67 words
The method of claim 1 in which step (b) includes the application of a predetermined tone scale function, step (e) comprises normalizing the value of the central image pixel input to the tone scale function with a scaling function based on the statistical characteristic, and step (f) comprises mapping the scaled value of the central pixel through the tone scale function to generate an intermediate output value.

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