## magnitude and direction

### munch kitty (view profile)

on 6 Feb 2012
Latest activity Answered by ANIMA V A

### ANIMA V A (view profile)

on 24 Nov 2015

how to calculate the magnitude and direction value of the images in matlab?(code)

Qura

on 29 Mar 2013

Walter Roberson

### Walter Roberson (view profile)

on 29 Mar 2013

Please start a new Question for this problem.

### Junaid (view profile)

on 6 Feb 2012

what do you mean by direction of images. I hope you are talking about gradient value and direction (orientation) ?

munch kitty

### munch kitty (view profile)

on 6 Feb 2012

yes absolutely.but the mag and dir value when we printed it shows for each pixel.i want the values for block by block.

Rupali

### Rupali (view profile)

on 6 Feb 2012

i want to know how to divide image into blocks ????????

munch kitty

### munch kitty (view profile)

on 8 Feb 2012

cbs=100;
ck1=1; cblock(:,:,:,1)=a1(1:100,1:100,:);
cblock(:,:,:,5)=a1(101:200,1:100,:);
cblock(:,:,:,9)=a1(201:300,1:100,:);
for ci1=1:3
ck1=ck1+1;
for cj1=1:3
row1=80 ;
row2=180;
cblock(:,:,:,ck1)=a1( (cbs*(ci1-1)+1:cbs*(ci1-1)+cbs), ((row1+1)+(cj1-1)*80:row2+(cj1-1)*80),:);

ck1=ck1+1;
end
end
we divide the image into 3X4.overlap of some pixels..u can also do non overlapping..

### Junaid (view profile)

on 6 Feb 2012

I think you want to compute the SIFT right ?

Anyway to divide the image into blocks, you can use following tip

in case you have difficulty you can share your code.

```angle = 360;
```
```[GradientX,GradientY] = gradient(double(img));
```
`    Gr = sqrt((GradientX.*GradientX)+(GradientY.*GradientY));`
```    index = GradientX == 0;
`     YX = GradientY./GradientX;`
`      A = ((atan2(GradientY,GradientX)+pi)*180)/pi; `

A contains the orientation of each pixel.

munch kitty

### munch kitty (view profile)

on 8 Feb 2012

junaki..the image block was posted above.for taht 12 blocks i have to calculate magnitude and orientation

mano

### mano (view profile)

on 8 Feb 2012

i found the gradient and magnitude but i want to how to found gradient magnitude histogram?if u know help me

Lee

### Lee (view profile)

on 25 Mar 2013

Hi Junaid, may I know why parameter YX is calculated?

### ANIMA V A (view profile)

on 24 Nov 2015

How to compute gradient in three different directions? Can any one help me i need to compute the gradient in 3 different directions for an image please help me