Question

我转换后的图片质量非常低。我尝试过使用setQuality方法，但它似乎没有改变任何东西。

这是将svg转换为png的代码的一部分：

SVGConverter svgConverter = new SVGConverter();
String[] sources = { "C:/imageData.svg" };
svgConverter.setSources(sources);
svgConverter.setDestinationType(DestinationType.PNG);
svgConverter.setDst(new File("C:/image.png"));

有谁知道如何让图像质量更好？

Answer 1

我在将SVG转换为PNG（使用字节数组）时使用此代码：

private byte[] renderPng(byte[] svgBytes) {
    try {
        TranscoderInput transcoderInput = new TranscoderInput(new ByteArrayInputStream(svgBytes));
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        TranscoderOutput transcoderOutput = new TranscoderOutput(output);

        Transcoder transcoder = null;
        String type = "png";
        if(type.equalsIgnoreCase("png")) { 
            transcoder = new PNGTranscoder()
            {
                @Override
                protected ImageRenderer createRenderer()
                {
                    ImageRenderer r = super.createRenderer();

                    RenderingHints rh = r.getRenderingHints();

                    rh.add(new RenderingHints(RenderingHints.KEY_ALPHA_INTERPOLATION,
                        RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY));
                    rh.add(new RenderingHints(RenderingHints.KEY_INTERPOLATION,
                        RenderingHints.VALUE_INTERPOLATION_BICUBIC));

                    rh.add(new RenderingHints(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON));

                    rh.add(new RenderingHints(RenderingHints.KEY_COLOR_RENDERING,
                        RenderingHints.VALUE_COLOR_RENDER_QUALITY));
                    rh.add(new RenderingHints(RenderingHints.KEY_DITHERING,
                        RenderingHints.VALUE_DITHER_DISABLE));

                    rh.add(new RenderingHints(RenderingHints.KEY_RENDERING,
                        RenderingHints.VALUE_RENDER_QUALITY));

                    rh.add(new RenderingHints(RenderingHints.KEY_STROKE_CONTROL,
                        RenderingHints.VALUE_STROKE_PURE));

                    rh.add(new RenderingHints(RenderingHints.KEY_FRACTIONALMETRICS,
                        RenderingHints.VALUE_FRACTIONALMETRICS_ON));
                    rh.add(new RenderingHints(RenderingHints.KEY_TEXT_ANTIALIASING,
                        RenderingHints.VALUE_TEXT_ANTIALIAS_OFF));

                    r.setRenderingHints(rh);

                    return r;
                }
            };

            transcoder.addTranscodingHint(PNGTranscoder.KEY_BACKGROUND_COLOR, Color.WHITE);
        } else {
            transcoder = new JPEGTranscoder();

            Float jpegQuality = new Float(0.95);
            // KEY_WIDTH - seems to pick it up just fine from the SVG charts.  Set to 560 otherwise.
            // KEY_QUALITY 0-1.0 with 1.0 being No Loss.  Value must be of type Float.  0.95 is 30% smaller and looks great.
            transcoder.addTranscodingHint(JPEGTranscoder.KEY_QUALITY, jpegQuality);
        }

        // NOTE: for linux you need Java 1.4.1+ AND the headless environment (e.g. export JAVA_OPTS='-Djava.awt.headless=true').
        try {
            transcoder.transcode(transcoderInput, transcoderOutput);
        }
        catch(Exception e) {
            logger.error("SVG To Raster response transcode exception", e);
            if(output != null) {
                output.close();
            }
            throw( new RuntimeException("SVG To Raster Filter Response Stream Exception", e) );
        }

        if(output != null) {
            output.flush();
            output.close();
        }

        transcoderInput  = null;
        transcoderOutput = null;
        transcoder = null;

        return output.toByteArray();
    } catch (Exception exc) {
        logger.error("Error in rendering png method", exc);
    }
    return new byte[0];
}

此外，SVG文档中的clipPath元素应包含此属性，否则会出现奇怪的伪像：

<clipPath shape-rendering="geometricPrecision" ... >

Answer 2

试试这个......

jpeg.addTranscodingHint(JPEGTranscoder.KEY_QUALITY, new Float(keyQuality));
jpeg.addTranscodingHint(JPEGTranscoder.KEY_HEIGHT, height*scalePercentage);
jpeg.addTranscodingHint(JPEGTranscoder.KEY_WIDTH, width*scalePercentage);
jpeg.addTranscodingHint(JPEGTranscoder.KEY_QUALITY, 1.0f);
jpeg.addTranscodingHint(JPEGTranscoder.KEY_BACKGROUND_COLOR, Color.WHITE);

你需要增加高度和宽度设置keyQuality 1.0f。

如果height = 200，则将高度增加200 * 3（高度* scalePercentage）。与宽度相似

Answer 3

在Apache Batik中，您可以通过传递代码转换器提示KEY_PIXEL_UNIT_TO_MILLIMETER来更改分辨率。

但是重要的是，您需要将高度和宽度缩放为与您要寻找的新分辨率相同的比例。

例如：

我的SVG尺寸为3.5 * 2.0英寸（252 * 144像素）。

目标分辨率为600 DPI。

int RESOLUTION_DPI = 600;
float SCALE_BY_RESOLUTION = RESOLUTION_DPI / 72f;
float scaledWidth = 252*SCALE_BY_RESOLUTION;
float scaledHeight = 144*SCALE_BY_RESOLUTION;
float pixelUnitToMM = new Float(25.4f/RESOLUTION_DPI);

transcoderInput = new TranscoderInput(svgDocument);
TranscoderOutput transcoderOutput = new TranscoderOutput(ostream);
transcoder.addTranscodingHint(ImageTranscoder.KEY_BACKGROUND_COLOR, Color.WHITE);
transcoder.addTranscodingHint(PNGTranscoder.KEY_WIDTH, scaledWidth);
transcoder.addTranscodingHint(PNGTranscoder.KEY_HEIGHT, scaledHeight);

transcoder.addTranscodingHint(PNGTranscoder.KEY_PIXEL_UNIT_TO_MILLIMETER, pixelUnitToMM);

transcoder.transcode(transcoderInput, transcoderOutput);

在Batik中使用SVGConverter将svg转换为png时图像质量较差

3 个答案: