Java change saturation giving distorted colors

Question

I am trying to change the saturation of an image by a certain amount but I am getting some strange results. I am using the following code

// shiftAmount should be a float value between -1 and 1
public static int[] saturation( int[] pixels, float shiftAmount )
{
        int[] newPixels = new int[ pixels.length ];

        for( int i = 0; i < pixels.length; i++ )
        {
            // get HSB color values
            Color rgb = new Color( pixels[ i ] );
            float[] hsb = Color.RGBtoHSB( rgb.getRed(), rgb.getGreen(), rgb.getBlue(), null );
            float hue =        hsb[ 0 ];
            float saturation = hsb[ 1 ];
            float brightness = hsb[ 2 ];

            // shift
            saturation += shiftAmount;
            if( saturation > 1f )
                saturation = 1f;
            else if( saturation < 0f )
                saturation = 0f;

            // convert HSB color back
            newPixels[ i ] = Color.HSBtoRGB( hue, saturation, brightness );
        }

        return newPixels;
}

Below is an example of 80% saturation shift in another image editing software (Aseprite) and one where I did it with my own code (using 0.8f).

Original image

What it looks like when I use Aseprite

What it looks like using my own code

As you can see, in the last image the colors are very distorted. Does anyone know how to solve this?