PixelAspectRatio.java

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 * The Original Code is part of dcm4che, an implementation of DICOM(TM) in
 * Java(TM), hosted at https://github.com/gunterze/dcm4che.
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 * The Initial Developer of the Original Code is
 * Agfa Healthcare.
 * Portions created by the Initial Developer are Copyright (C) 2011
 * the Initial Developer. All Rights Reserved.
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 * See @authors listed below
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package org.dcm4che3.image;

import org.dcm4che3.data.Tag;
import org.dcm4che3.data.Attributes;

/**
 * @author Gunter Zeilinger <gunterze@gmail.com>
 *
 */
public class PixelAspectRatio {

    public static float forImage(Attributes attrs) {
        return forImage(attrs, Tag.PixelAspectRatio,
            Tag.PixelSpacing,
            Tag.ImagerPixelSpacing,
            Tag.NominalScannedPixelSpacing);
    }

    public static float forPresentationState(Attributes attrs) {
        return forImage(attrs, Tag.PresentationPixelAspectRatio,
                Tag.PresentationPixelSpacing);
    }

    private static float forImage(Attributes attrs, int aspectRatioTag,
            int... pixelSpacingTags) {
        int[] ratio = attrs.getInts(aspectRatioTag);
        if (ratio != null && ratio.length == 2
                && ratio[0] > 0 && ratio[1] > 0)
            return (float) ratio[0] / ratio[1];

        for (int pixelSpacingTag : pixelSpacingTags) {
            float[] spaces = attrs.getFloats(pixelSpacingTag);
            if (spaces != null && spaces.length == 2
                    && spaces[0] > 0 && spaces[1] > 0)
                return spaces[0] / spaces[1];
        }
        return 1f;
    }

}