Computing first derivative--image processing

21 次查看（过去 30 天）
MLnoob5340
MLnoob5340 2014-11-22
评论： Image Analyst 2014-11-23
I need help understanding computer first derivative
I don't understand how to derivative of [5 5 5 4 4 3 4 3 4 5 2 2 2 2 1 1 1]
is
[X 0 -1 0 -1 1 -1 1 1 -3 0 0 0 -1 0 0 X]

请先登录，再回答此问题。

回答（2 个）

Image Analyst
Image Analyst 2014-11-23
It's just the (n+1)st element minus the nth element. Same as you'd get from diff(). There are also imgradient(), and imgradientxy() functions in the Image Processing Toolbox.
  2 个评论
MLnoob5340
MLnoob5340 2014-11-23
Okay! how would I find the second derivative do the same process again?
Image Analyst
Image Analyst 2014-11-23
Yeah, you can do that. What do you really want to do anyway? Why don't you post your image and say what you want to measure in it or do to it?

请先登录，再进行评论。

Youssef Khmou
Youssef Khmou 2014-11-23
In general diff(X,n) of N by 1 vector returns an N-n by 1 vector, second derivative is diff(X,2), using gradient is better because it offers a possibility to choose the sample rate, if its 1 then :
d2x=gradient(gradient(x));

类别

在 Help Center 和 File Exchange 中查找有关 Image Segmentation and Analysis 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by