ImageIO写特定的tiff

Question

我尝试将图像（使用ImageIO - > https://github.com/haraldk/TwelveMonkeys）转换为特定的tiff，就像imagemagick那样。我有一个输入图像，想要写下以下特定的tiff：

PLANAR_CONFIGURATION = 1
SAMPLES_PER_PIXEL = 1
BITS_PER_SAMPLE = 1
Y_RESOLUTION = 196
X_RESOLUTION = 204
IMAGE_WIDTH = 1728

知道如何渲染输入流吗？目前图像刚刚转换为tiff。

BufferedImage image = ImageIO.read(inputstream)
ImageIO.write( image, "tiff", outputstream );

Answer 1

正如@ fmw42所说，使图像成为1位你自己做了。 TIFFImageWriter插件将按原样写入传递的图像。幸运的是，这并不难做到。

这是一种将图像转换为二进制的简单（但不是非常复杂）的方法：

private static BufferedImage toBinary(BufferedImage original) {
    if (original.getType() == BufferedImage.TYPE_BYTE_BINARY) {
        return original;
    }

    // Quick and unsophisticated way to convert to B/W binary, using default dither and threshold (fixed, 50% I think)
    BufferedImage image = new BufferedImage(original.getWidth(), original.getHeight(), BufferedImage.TYPE_BYTE_BINARY);
    Graphics2D g = image.createGraphics();
    try {
        g.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
        g.setComposite(AlphaComposite.Src);
        g.drawImage(original, 0, 0, null);
    }
    finally {
        g.dispose();
    }

    return image;
}

我将把它留作练习来编写更高级的解决方案，使用自适应阈值处理，误差扩散抖动等。

现在你可以使用以下代码了，你几乎就在那里：

public static void main(String[] args) throws IOException {
    BufferedImage original = ImageIO.read(new File(args[0]));
    ImageIO.write(toBinary(original), "TIFF", new File("out.tif"));
}

不幸的是，这不会设置X和Y分辨率标签。如果您也需要它，您必须深入了解ImageIO API，并找出如何使用元数据来控制输出。请注意，只能以这种方式设置元数据中的某些值。其他值将根据传入的图像数据计算，并且一些值可由作者用默认值填充。

您可以使用以下代码（toBinary方法与上面相同）：

public static void main(String[] args) throws IOException {
    BufferedImage original = ImageIO.read(new File(args[0]));

    BufferedImage image = toBinary(original);

    ImageWriter writer = ImageIO.getImageWritersByFormatName("TIFF").next();

    try (ImageOutputStream stream = ImageIO.createImageOutputStream(new File("out.tif"))) {
        // You may use the param to control compression
        ImageWriteParam param = writer.getDefaultWriteParam();

        IIOMetadata metadata = writer.getDefaultImageMetadata(ImageTypeSpecifier.createFromRenderedImage(image), param);
        Node root = metadata.getAsTree("com_sun_media_imageio_plugins_tiff_image_1.0"); // "javax_imageio_tiff_image_1.0" will work in later versions
        Node ifd = root.getFirstChild();
        // Add X and Y resolution tags
        ifd.appendChild(createResTag("282", "XResolution", "204/1"));
        ifd.appendChild(createResTag("283", "YResolution", "196/1"));

        // Merge changes back to metadata
        metadata.mergeTree("com_sun_media_imageio_plugins_tiff_image_1.0", root);

        // Write full image, with metadata
        writer.setOutput(stream);
        writer.write(null, new IIOImage(image, null, metadata), param);
    }
    finally {
        writer.dispose();
    }
}

private static IIOMetadataNode createResTag(String tagNumber, String tagName, String tagValue) {
    IIOMetadataNode res = new IIOMetadataNode("TIFFField");
    res.setAttribute("number", tagNumber);
    res.setAttribute("name", tagName); // Tag name is optional

    IIOMetadataNode value = new IIOMetadataNode("TIFFRational");
    value.setAttribute("value", tagValue);

    IIOMetadataNode rationals = new IIOMetadataNode("TIFFRationals");
    rationals.appendChild(value);
    res.appendChild(rationals);

    return res;
}

PS：TwelveMonkeys TIFF插件目前不写PlanarConfiguration: 1，因为这是默认值，并且没有办法强迫它。但这并不重要，因为在这种情况下，所有兼容的TIFF软件都必须使用默认值。