Perceptual thresholding for gradient-based local edge detection
AssigneeIntel Corporation
InventorsTinku Acharya, Ping-Sing Tsai
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Abstract
What is disclosed is a method for dynamically and automatically determining the threshold value for edge detection based on localized intensity information. Each pixel can be assigned a threshold to which its gradient or other intensity change information can be compared so as to detect whether or not the pixel belongs to an edge feature of the image or not. Further, the thresholding can be based upon the response of the human vision system so that visual appearance of the image to users is considered when analyzing localized intensity information. The localized thresholding technique can be applied to any edge detection scheme.
Claims22
A method comprising:
- defining a localization region of an image, said localization region including a selected portion of said image;
- and
- determining automatically, without user intervention, a threshold applied for edge detection within said localization region based on intensity information of pixels within said localization region, said threshold determined by a power function operator reflective of perceptual characteristics as it relates to intensity of a human vision system, said power function operator is a measure of relative localization intensity raised to a power factor;
- wherein said relative localization intensity is a quotient of a difference between a mean and a minimum of all intensity values within said localization region and a difference between a maximum and said minimum of all intensity values within said localization region.
A method according to claim 10 wherein said magnitude is obtained by:
- squaring said first direction differential;
- squaring said second direction differential;
- summing said squared first and second direction differentials;
- and
- extracting said square root of said sum, said magnitude set to equal said square root.
An article comprising a computer readable medium including instructions stored thereon that when executed by a processor, cause:
- defining a localization region of an image, said localization region including a selected portion of said image;
- and
- determining automatically, without user intervention, a threshold applied for edge detection within said localization region based on intensity information of pixels within said localization region, said threshold determined by a power function operator reflective of perceptual characteristics as it relates to intensity of a human vision system, said power function operator is a measure of relative localization intensity raised to a power factor;
- wherein said relative localization intensity is a quotient of a difference between a mean and a minimum of all intensity values within said localization region and a difference between a maximum and said minimum of all intensity values within said localization region.
Dependencies are inferred from the claim text.