以编程方式减小JPEG文件大小 [英] Programmatically Reducing JPEG file size

问题描述

为任何无知而道歉，但是我以前从未在Java中使用过jpeg图像（更不用说任何类型的图像了）。

Apologies for any ignorance, but I have never worked with jpeg images (let alone any types of images) in Java before.

假设我想发送jpeg Web服务到客户端的图像。有什么方法可以通过以某种方式处理图像的颜色配置文件来减小jpeg文件的大小？

Supposing I want to send a jpeg image from a web service to a client. Is there any way that I can reduce the jpeg file size by manipulating the colour profile of the image in some way?

我已经能够通过以下方式减小图像大小：使用名为 imgscalr 的整齐的BufferedImages工具对其进行缩放。请参见此处。

I have already been able to reduce the image size by scaling it using a neat tool for BufferedImages called imgscalr. See here.

我还希望jpeg的颜色少于高质量的jpeg图像。例如，我希望能够在jpeg中使用8位颜色而不是16位颜色。

I would also like a jpeg that has less colours than a high quality jpeg image. For example, I would like to be able to use 8bit colour in my jpeg instead of say 16bit colour.

如果我有一个BufferedImage，我将需要更改什么？ Java的2D软件包？

What exactly would I need to change if I have a BufferedImage from Java's 2D package?

推荐答案

减小图像大小的另一种方法是更改​​压缩级别。您可以使用ImageWriter做到这一点。

Another way to reduce image size is to change compression level. You can do that using ImageWriter.

    ImageWriter writer = null;
    Iterator<ImageWriter> iwi = ImageIO.getImageWritersByFormatName("jpg");
    if (!iwi.hasNext())
        return;
    writer = (ImageWriter) iwi.next();
    ImageWriteParam iwp = writer.getDefaultWriteParam();
    iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT) ;
    iwp.setCompressionQuality(compressionQuality);
    writer.setOutput(...);
    writer.write(null, image, iwp);

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