/*
 * Copyright (c) 2011-2016, Peter Abeles. All Rights Reserved.
 *
 * This file is part of BoofCV (http://boofcv.org).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package boofcv.examples.segmentation;

import boofcv.alg.color.ColorHsv;
import boofcv.gui.image.ImagePanel;
import boofcv.gui.image.ShowImages;
import boofcv.io.UtilIO;
import boofcv.io.image.ConvertBufferedImage;
import boofcv.io.image.UtilImageIO;
import boofcv.struct.image.GrayF32;
import boofcv.struct.image.Planar;
import georegression.metric.UtilAngle;

import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;

/**
 * Example which demonstrates how color can be used to segment an image.  The color space is converted from RGB into
 * HSV.  HSV separates intensity from color and allows you to search for a specific color based on two values
 * independent of lighting conditions.  Other color spaces are supported, such as YUV, XYZ, and LAB.
 *
 * @author Peter Abeles
 */
public class ExampleSegmentColor {

	/**
	 * Shows a color image and allows the user to select a pixel, convert it to HSV, print
	 * the HSV values, and calls the function below to display similar pixels.
	 */
	public static void printClickedColor( final BufferedImage image ) {
		ImagePanel gui = new ImagePanel(image);
		gui.addMouseListener(new MouseAdapter() {
			@Override
			public void mouseClicked(MouseEvent e) {
				float[] color = new float[3];
				int rgb = image.getRGB(e.getX(),e.getY());
				ColorHsv.rgbToHsv((rgb >> 16) & 0xFF, (rgb >> 8) & 0xFF, rgb & 0xFF, color);
				System.out.println("H = " + color[0]+" S = "+color[1]+" V = "+color[2]);

				showSelectedColor("Selected",image,color[0],color[1]);
			}
		});

		ShowImages.showWindow(gui,"Color Selector");
	}

	/**
	 * Selectively displays only pixels which have a similar hue and saturation values to what is provided.
	 * This is intended to be a simple example of color based segmentation.  Color based segmentation can be done
	 * in RGB color, but is more problematic due to it not being intensity invariant.  More robust techniques
	 * can use Gaussian models instead of a uniform distribution, as is done below.
	 */
	public static void showSelectedColor( String name , BufferedImage image , float hue , float saturation ) {
		Planar input = ConvertBufferedImage.convertFromMulti(image,null,true,GrayF32.class);
		Planar hsv = input.createSameShape();

		// Convert into HSV
		ColorHsv.rgbToHsv_F32(input,hsv);

		// Euclidean distance squared threshold for deciding which pixels are members of the selected set
		float maxDist2 = 0.4f*0.4f;

		// Extract hue and saturation bands which are independent of intensity
		GrayF32 H = hsv.getBand(0);
		GrayF32 S = hsv.getBand(1);

		// Adjust the relative importance of Hue and Saturation.
		// Hue has a range of 0 to 2*PI and Saturation from 0 to 1.
		float adjustUnits = (float)(Math.PI/2.0);

		// step through each pixel and mark how close it is to the selected color
		BufferedImage output = new BufferedImage(input.width,input.height,BufferedImage.TYPE_INT_RGB);
		for( int y = 0; y < hsv.height; y++ ) {
			for( int x = 0; x < hsv.width; x++ ) {
				// Hue is an angle in radians, so simple subtraction doesn't work
				float dh = UtilAngle.dist(H.unsafe_get(x,y),hue);
				float ds = (S.unsafe_get(x,y)-saturation)*adjustUnits;

				// this distance measure is a bit naive, but good enough for to demonstrate the concept
				float dist2 = dh*dh + ds*ds;
				if( dist2 <= maxDist2 ) {
					output.setRGB(x,y,image.getRGB(x,y));
				}
			}
		}

		ShowImages.showWindow(output,"Showing "+name);
	}

	public static void main( String args[] ) {
		BufferedImage image = UtilImageIO.loadImage(UtilIO.pathExample("sunflowers.jpg"));

		// Let the user select a color
		printClickedColor(image);
		// Display pre-selected colors
		showSelectedColor("Yellow",image,1f,1f);
		showSelectedColor("Green",image,1.5f,0.65f);
	}
}