How to get the gradient of a pixel?

I am doing block processing on a fingeprint image and I will like to get the gradient of all the pixels in their x and y components separately using a sobel filter. I am doing this block by block.

I saw the function imgradient() but after reading the documentation it seems to be getting the gradient for the whole image that is passed to it, which in my case will be the block, except i understood wrongly, and if i did please help me out or is there any function i can use to get the gradient of just one pixel in the image block.

[darova]

gradient is difference

One pixel has only one value. What kind of gradient do you want to calculate?

[Fego Etese]

Hey darova, thanks for your time again, I understand better, but stil i have to calculate the gradient of all the pixels in an image, how do you suppose i go about that?

[darova]

• i can use to get the gradient of just one pixel in the image block.

I don't understand this sentence

[Fego Etese]

I may have confused you as i was confused myself too. Sory about that. But what i really wanted to get was the angle and magnitude using the gradient. I have tried it out and seen imgradient() can do it. I just didnt understand how to use the function. It will provide me with the angle of all the pixels in one matrix and the magnitude in the other.

But another issue is how can i use the quiver function to draw arrows like the one in the picture i sent using this angle and magnitude data?

thanks