can u please tell me how to write the number of unique hues included in an in matlab?

i have written a code

image = imread('filename');
figure, imshow(image);
hsv_image = rgb2hsv(image);
i = hsv_image(:,:,2)>0.2.* (hsv_image(:,:,3)>0.15 .* hsv_image(:,:,3)<0.95);
figure
hist(i,20);

and further i would like to know how to do this in matlab.

Suppose Q is the maximum value of the histogram. Let the
hue count be the number of bins with values greater than c ⋅Q ,
q = maximum value in histogram
N = {i | H(i) > cq}
here C= 0.1.

plz help me......

Answer 1

[Image Analyst]

I don't know what you're doing by calculating i. What's the point of that? To get the number of unique hues, you can use the unique() function.

hsv = rgb2hsv(rgbImage);
hueImage = hsv(:,:,1);
numberOfUniqueHues = unique(hueImage)

[mohammed]

ok i will tell you in detail

Convert image to HSV
Consider pixels with brightness in [0.15,0.95] and saturation > 0.2
Construct 20-bin histogram on hue values
q = maximum value in histogram

N = {i | H(i) > q*c}

c =0.1 sets noise sensitivity

20 - |N| is the number of “unused” hues. and i have to write a program for N.

[Image Analyst]

hsv = rgb2hsv(rgbImage);
hueImage = hsv(:,:,1);
satImage = hsv(:,:,2);
valueImage = hsv(:,:,3);
mask = valueImage > 0.2 & valueImage < 0.95 & satImage > 0.2;
H = hist(hueImage(mask));
q = max(hueImage(mask));
c = 0.1;
mask2 = hueImage > q*c;
N = your homework.

[mohammed]

THANKS A LOT.........

[mohammed]

hi i have a doubt can u please tell me why did u take q = max(hueImage(mask));

b.coz i want max value of histogram

so it could be q = max(H);

plz tell me which one is right.

[Image Analyst]

I have no idea what your algorithm will do. All I know is that you want the max value of the histogram. That is ambiguous. Do you want the max bin value (x value) or the max counts value (max y value)? I gave you the max hue value (x value, not binned). If you want the max count value, you can do what you said, but I have no idea which is right because I don't know what the algorithm is planning to do after you find that value.

[mohammed]

thanks for replay.. actually i want to write a program for.

f = # of{ i | h( i) > c ⋅Q }

The number of pixels that belong to the most frequent hue is calculated as:

f = max{h (i)}

The hue contrast can be calculated as :

f = max(|| I(i) – I(j)||) ,

i, j ∈ {k | h (k) > c ⋅Q }

where I(i) is the center hue of the ith bin in the hue histogram. The distance metric • refers to the arc-length distance on the hue wheel.

but i am unable to understand how to formulate in matlab....... plz help me......

[Image Analyst]

Then you want the max of the counts.

Perhaps you'd be interested in the color frequency image: http://www.mathworks.com/matlabcentral/fileexchange/28164-color-frequency-image

Answer 2

[Walter Roberson]

h = hist(hsv_image(i), 20);
q = max(h);

[mohammed]

thanks .

i have try this but i want only the max value of data. moreover then how to calculate N.