网站的购物车怎么做,大型电子商务网站建设公司,化州市建设局网站,做网站的意义是什么因为java默认的图片像素分辨率DPI72#xff0c;分辨率有点低。所以研究了一下如何创建指定DPI的方案。
DPI#xff1a; 指的是每英尺的像素点(dots per inch)
JPEG图片
JPEG图片的元数据定义参看oracle官网。 https://docs.oracle.com/javase/8/docs/api/javax/imageio/me…因为java默认的图片像素分辨率DPI72分辨率有点低。所以研究了一下如何创建指定DPI的方案。
DPI 指的是每英尺的像素点(dots per inch)
JPEG图片
JPEG图片的元数据定义参看oracle官网。 https://docs.oracle.com/javase/8/docs/api/javax/imageio/metadata/doc-files/jpeg_metadata.html
参数说明
参数默认值说明resUnits0单位(0 no units, just aspect ratio; 1 dots/inch; 2 dots/cm)Xdensity1The horizontal density or aspect ratio numeratorYdensity1The vertical density or aspect ratio denominator
如下代代码创建一张分辨率为300DPIdots/inch的jpg图片。 String path res.jpg;
final BufferedImage image new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d image.createGraphics();
// // fill all the image with white
g2d.setColor(Color.white);
g2d.fillRect(0, 0, w, h);// Disposes of this graphics context and releases any system resources that it is using.
g2d.dispose();ImageIO.write(image, jpg, Files.newOutputStream(Paths.get(path)));final ImageWriter writer ImageIO.getImageWritersBySuffix(jpeg).next();
// writeParams.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
//调整图片质量
// writeParams.setCompressionQuality(1f);ImageOutputStream ios ImageIO.createImageOutputStream(new File(path));
writer.setOutput(ios);ImageWriteParam param writer.getDefaultWriteParam();
IIOMetadata metadata writer.getDefaultImageMetadata(new ImageTypeSpecifier(image.getColorModel(), image.getSampleModel()), param);
Element tree (Element) metadata.getAsTree(javax_imageio_jpeg_image_1.0);
Element jfif (Element) tree.getElementsByTagName(app0JFIF).item(0);
jfif.setAttribute(Xdensity, 300);
jfif.setAttribute(Ydensity, 300);
jfif.setAttribute(resUnits, 1); // density is dots per inchmetadata.mergeTree(javax_imageio_jpeg_image_1.0, tree);
writer.write(null, new IIOImage(image, null, metadata), param);
writer.dispose();
可以在ps上看到分辨率是300.打开ps点击“图像”-“图像大小”
TIFF图片
commons-imaging 对Tiff的支持比较好。
使用commons-imaging 创建一张分辨率为300DPIdots/inch的tiff图片。
dependencygroupIdorg.apache.commons/groupIdartifactIdcommons-imaging/artifactIdversion1.0-alpha3/version
/dependencyString path res.tif;
final BufferedImage image new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
final TiffImagingParameters params new TiffImagingParameters();
final PixelDensity pixelDensity PixelDensity.createFromPixelsPerInch(300, 300);
params.setPixelDensity(pixelDensity);
TiffImageParser tiffImageParser new TiffImageParser();
tiffImageParser.writeImage(image, new FileOutputStream(path), params);final ImageInfo imageInfo Imaging.getImageInfo(new File(path));
if (imageInfo ! null) {final int xReadDPI imageInfo.getPhysicalWidthDpi();final int yReadDPI imageInfo.getPhysicalHeightDpi();System.out.println(xReadDPI);System.out.println(yReadDPI);
}ps查看下分辨率。确实是300.
