降低java中的图像分辨率

发布于 2024-11-16 08:58:36 字数 114 浏览 2 评论 0原文

我需要使用Java程序减小图像的大小（不是宽度和高度）。他们有什么好的 API 可以用于此吗？

我需要将大小从 1MB 减少到大约 50kb - 100 kb。当然，分辨率会降低，但这并不重要。

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古镇旧梦 2024-11-23 08:58:36

根据这篇博客文章： http://i-proving.com/ 2006/07/06/java-advanced-imaging/ 您可以使用Java 高级成像库来完成您想要的操作。以下示例代码应该为您提供一个良好的起点。这将调整图像的高度和宽度以及图像质量。一旦图像达到所需的文件大小，您可以在显示图像时将其缩放回所需的像素高度和宽度。

// read in the original image from an input stream
SeekableStream s = SeekableStream.wrapInputStream(
  inputStream, true);
RenderedOp image = JAI.create("stream", s);
((OpImage)image.getRendering()).setTileCache(null);

// now resize the image

float scale = newWidth / image.getWidth();

RenderedOp resizedImage = JAI.create("SubsampleAverage", 
    image, scale, scale, qualityHints);


// lastly, write the newly-resized image to an
// output stream, in a specific encoding

JAI.create("encode", resizedImage, outputStream, "PNG", null);

According to this blog post: http://i-proving.com/2006/07/06/java-advanced-imaging/ you can use the Java Advanced Imaging Library to do what you want. The following sample code should provide you a good starting point. This will resize the image, both in height and width, as well as image quality. Once your image is of the desired file size, you can scale it back up to your desired pixel height and width when you display the image.

// read in the original image from an input stream
SeekableStream s = SeekableStream.wrapInputStream(
  inputStream, true);
RenderedOp image = JAI.create("stream", s);
((OpImage)image.getRendering()).setTileCache(null);

// now resize the image

float scale = newWidth / image.getWidth();

RenderedOp resizedImage = JAI.create("SubsampleAverage", 
    image, scale, scale, qualityHints);


// lastly, write the newly-resized image to an
// output stream, in a specific encoding

JAI.create("encode", resizedImage, outputStream, "PNG", null);

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梦年海沫深 2024-11-23 08:58:36

这是工作代码

public class ImageCompressor {
    public void compress() throws IOException {
        File infile = new File("Y:\\img\\star.jpg");
        File outfile = new File("Y:\\img\\star_compressed.jpg");

        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
                infile));
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream(outfile));

        SeekableStream s = SeekableStream.wrapInputStream(bis, true);

        RenderedOp image = JAI.create("stream", s);
        ((OpImage) image.getRendering()).setTileCache(null);

        RenderingHints qualityHints = new RenderingHints(
                RenderingHints.KEY_RENDERING,
                RenderingHints.VALUE_RENDER_QUALITY);

        RenderedOp resizedImage = JAI.create("SubsampleAverage", image, 0.9,
                0.9, qualityHints);

        JAI.create("encode", resizedImage, bos, "JPEG", null);

    }

    public static void main(String[] args) throws IOException {

        new ImageCompressor().compress();
    }
}

这个代码对我来说工作得很好。如果您需要调整图像大小，那么您可以
在此更改 x 和 y 比例 JAI.create("SubsampleAverage", image, xscale,yscale,qualityHints);

This is the working code

public class ImageCompressor {
    public void compress() throws IOException {
        File infile = new File("Y:\\img\\star.jpg");
        File outfile = new File("Y:\\img\\star_compressed.jpg");

        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
                infile));
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream(outfile));

        SeekableStream s = SeekableStream.wrapInputStream(bis, true);

        RenderedOp image = JAI.create("stream", s);
        ((OpImage) image.getRendering()).setTileCache(null);

        RenderingHints qualityHints = new RenderingHints(
                RenderingHints.KEY_RENDERING,
                RenderingHints.VALUE_RENDER_QUALITY);

        RenderedOp resizedImage = JAI.create("SubsampleAverage", image, 0.9,
                0.9, qualityHints);

        JAI.create("encode", resizedImage, bos, "JPEG", null);

    }

    public static void main(String[] args) throws IOException {

        new ImageCompressor().compress();
    }
}

This code is Working Great for me. if you need to resize the image then you can
change the x and y scale here JAI.create("SubsampleAverage", image, xscale,yscale, qualityHints);

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