/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   *  Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   *  Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *
 *   *  Neither the name of the University of Southampton nor the names of its
 *      contributors may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 */
package org.openimaj.image.objectdetection;

import java.util.List;

import org.openimaj.image.Image;
import org.openimaj.image.objectdetection.filtering.DetectionFilter;
import org.openimaj.math.geometry.shape.Rectangle;

/**
 * Interface describing a basic object detector for images. Any type of Java
 * object can be used to represent a detection; this could be something as
 * simple as a {@link Rectangle} representing the spatial location of the
 * detection, or it could be much more complex.
 * <p>
 * The interface allows for multiple detections to be returned from the input
 * image. If required, these detections could be filtered by a
 * {@link DetectionFilter} as a post-processing operation.
 * <p>
 * This interface is implicitly for single-scale detection. If your detector
 * works at multiple scales, then implementing the
 * {@link MultiScaleObjectDetector} would be a better idea.
 *
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 *
 * @param <IMAGE>
 *            The image on which to perform the detection
 * @param <DETECTED_OBJECT>
 *            the type of object representing a detection.
 */
public interface ObjectDetector<IMAGE extends Image<?, IMAGE>, DETECTED_OBJECT> {
        /**
         * Detect objects in the given image and return representations of them.
         * Representations often cover things like the spatial location in the image
         * of the detected object, however, this is implementation defined.
         * <p>
         * If no objects are detected, <code>null</code> or an empty list may be
         * returned.
         *
         * @param image
         *            the image to detect the object in.
         * @return a list of detections or <code>null</code> if none are found.
         */
        public List<DETECTED_OBJECT> detect(IMAGE image);

        /**
         * (Optional operation).
         * <p>
         * Set the region of interest within the image to search for objects.
         * Setting to <code>null</code> means to search the whole image.
         *
         * @param roi
         *            the region of interest
         */
        public void setROI(Rectangle roi);
}