how to get a uniform illumination?

hello, i am trying to do a face detection based on skin colour and i was trying to make a uniform illumination for the images acquired through the webcam. How can I do this with help of HSV adjustments?

Answer 1

[Image Analyst]

Illumination cannot be changed by software. You need things like lamps and diffusers. Simply converting to HSV or LAB color space and making the V or L channel (respectively) a uniform value does not have the same effect. Below is an image where I made the left half have the same Y value (like L or V). You can see the effect. If you would have had a non-uniform illumination, it would not flatten the image. You'd need to do background division for that.

[amir]

thanks for your explanation. I have these two images. What method would you think is suitable for this purpose?

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[Image Analyst]

I don't think you need uniform illumination. Why do you think you do?

[amir]

I was just playing around with HSV parameters to get the skin colour of face area but i couldn't get it properly, since there is different lightning around the face. Would you please guide me to get the skin colour or which parameters I am supposed to work on?

thank you.

[Image Analyst]

I'd try color segmentation in the HSV color space. Have you opened this image in the Color Thresholder app yet? Click on the Apps tab on the main tool ribbon in MATLAB, then click Color Thresholder.

[amir]

I have tried with color thresholder but the image is so noisy in the face area. Since I am going to do this method for real time processing, the result would not be stable since i have tried it with different photos. There is anyway I can overcome this problem?

[Image Analyst]

Try to do some noise reduction. For example average video frame together, or use some denoising algorithm.