MATLAB - How to eliminate shadowed background on an image

Question

I am trying to process a picture. There is an RGB leaf photograph and I want to exract the leaf's itself only.

The procedure I follow is

1. I read image from file
2. Convert to grayscale
3. Apply 5x5 median filter
4. Convert to BW

As you see the shadow on the bottom right corner sticks to the BW image. Is there a method to select the leaf only.

I = imread(files{404});

hcsc = vision.ColorSpaceConverter;        
hcsc.Conversion = 'RGB to intensity';       
Ig = step(hcsc, I);

medFilt= vision.MedianFilter([f f]);
Ig = step(medFilt, Ig);

at = vision.Autothresholder;        
Ibw = step(at, Ig);

Answer 1

Instead of converting to grayscale image, I convert it to HSV and take its V part. It results better now.

I = imread(files{404});

I = rgb2hsv(I);

Ig = I(:,:,3);

medFilt= vision.MedianFilter([f f]);
Ig = step(medFilt, Ig);

at = vision.Autothresholder;        
Ibw = step(at, Ig);