Thresholding operation on HSV Image

I wish to do thresholding operation on a HSV Image converted from an RGB image. Is there any function like imtool()for RGB images that display the HSV Values of a pixel?

Answer 1

[Image Analyst]

Yes. My demo "Simple color detection by hue" in my File Exchange does that. http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 Also there is an interactive thresholding application.

[Image Analyst]

You can use impixelinfo() to have the value of the three channel image that's being displayed show up in a little static text box as you mouse around. The image can be RGB, grayscale, or HSV. Let me know if you can't figure it out. You may have to play around with the 'Position' option to see the text.

Answer 2

[kartheek]

Dear Analyst

Thank you for your answer. But, is there a way where we can see the instantaneous values of H,S,V in the same way we can get values of R,G,B when I hover the cursor over the pixels using imtool()? coz, I want H,S,V values for only a particular region of image

[Jeff E]

Have you tried using the rgb2hsv function to convert your image to an HSV image? You can then use the imtool function as you would with an RGB image. True, the image will look a little weird, but you will get the desired functionality with the red channel = hue , green = saturation , blue = value. Try it with a RGB color wheel to start with and see if it makes sense.

[kartheek]

I have used rgb2hsv(). but the values it is showing are less than 1. Do I have to use the RGB to HSV Conversion formula again to get my original HSV values?

[Image Analyst]

No. What original HSV values? As far as I know there is only one hsv image, and it has values between 0 and 1, like it should. Exactly what are you expecting?

[JESU]

channel1Min = 0.825;

channel1Max = 0.451;

% Create mask based on chosen histogram thresholds

sliderBW = ( (H(:,:,1) >= channel1Min) | (H(:,:,1) <= channel1Max) );

BW = sliderBW;

Answer 3

[Image Analyst]

You can use the Color Thresholder app on the Apps tab of the tool ribbon to interactively threshold the color image by moving sliders.