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I found the definition of the gradient to need further clarification:
The gradient of an image is given by the formula :
where :
For instance:
What is ?
What is ?
Are these unit vectors?
And, should there be a link to computing the discrete gradient for the definition of the gradient for the x and y directions?
I was honestly confused here.
FAdmMatt ( talk) 07:46, 28 January 2014 (UTC)
This article contravenes the convention that "dark" image regions represent "low" values and "bright" image regions represent "high" values. Should simply reverse the sense of these words and the accompanying graphic.—Preceding unsigned comment added by Kennyhunt ( talk • contribs) 16:24, August 17, 2006
These two articles give different names to the same thing. As gradient is the more common term, they should be merged here, and color progression change to a redirect. -- jacobolus (t) 21:56, 20 September 2007 (UTC)
"The Sobel operator represents a rather inaccurate approximation of the image gradient"
The image gradient is the gradient of an assumed (not uniquely defined) function. What does it mean to be inaccurate? Surely we can construct a continuous function that takes on the discrete pixel values and matches the sobel derivative, then the sobel value would be exact and anything else would be inaccurate.
That statement needs to be cited and explained or removed. Likewise "It turns out that the derivatives at any particular point are functions of the intensity values at virtually all image points" is nonsense without some further assumption about the nature of the assumed continuous function.
99.56.163.151 ( talk) 23:23, 19 March 2012 (UTC)
![]() | This article is rated Stub-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||
|
I found the definition of the gradient to need further clarification:
The gradient of an image is given by the formula :
where :
For instance:
What is ?
What is ?
Are these unit vectors?
And, should there be a link to computing the discrete gradient for the definition of the gradient for the x and y directions?
I was honestly confused here.
FAdmMatt ( talk) 07:46, 28 January 2014 (UTC)
This article contravenes the convention that "dark" image regions represent "low" values and "bright" image regions represent "high" values. Should simply reverse the sense of these words and the accompanying graphic.—Preceding unsigned comment added by Kennyhunt ( talk • contribs) 16:24, August 17, 2006
These two articles give different names to the same thing. As gradient is the more common term, they should be merged here, and color progression change to a redirect. -- jacobolus (t) 21:56, 20 September 2007 (UTC)
"The Sobel operator represents a rather inaccurate approximation of the image gradient"
The image gradient is the gradient of an assumed (not uniquely defined) function. What does it mean to be inaccurate? Surely we can construct a continuous function that takes on the discrete pixel values and matches the sobel derivative, then the sobel value would be exact and anything else would be inaccurate.
That statement needs to be cited and explained or removed. Likewise "It turns out that the derivatives at any particular point are functions of the intensity values at virtually all image points" is nonsense without some further assumption about the nature of the assumed continuous function.
99.56.163.151 ( talk) 23:23, 19 March 2012 (UTC)