Convert picture to customized size

Posted on | Edited on | In

Main method

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
public static BufferedImage imageConvert(InputStream inputStream, Integer limit) throws IOException {
    if (inputStream == null || limit == null) return null;
    // init
    BufferedImage inputImage = ImageIO.read(inputStream);
    int size = getImageSize(inputImage);
    if (size <= 0 || inputImage == null) return null;

    // loop reduce pixel
    while (size > imgLimit) {
        // calculate edge shrink propotion
        // minus .05 improve convert speed
        double rate = (double)imgLimit/size - .05;
        // if origin is 20 times than limit, rate may little than 0
        // set ten times smaller than origin as default
        if (rate < 0) rate = .1;
        rate = Math.sqrt(rate);

        int width = (int)(inputImage.getWidth(null) * rate);
        int height = (int)(inputImage.getHeight(null) * rate);
        BufferedImage outputImage = imageCompress(inputImage, width, height);
        inputImage = outputImage;

        // recalculate
        size = getImageSize(inputImage);
    }
    return inputImage;
}

Assistant method

1
2
3
4
5
6
7
public static int getImageSize(BufferedImage img) throws IOException {
    ByteArrayOutputStream byteOS = new ByteArrayOutputStream();
    ImageIO.write(img, "jpg", byteOS);
    int size = byteOS.size();
    byteOS.close();
    return size;
}
1
2
3
4
5
6
7
8
9
10
11
12
13
public static BufferedImage imageCompress(Image img, int w, int h) throws IOException {
    BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB );
    // redraw converted graph
    image.getGraphics().drawImage(img, 0, 0, w, h, null);

    ByteArrayOutputStream byteOS = new ByteArrayOutputStream(256);
    ImageIO.write(image, "jpg", byteOS);
    ByteArrayInputStream byteIS = new ByteArrayInputStream(byteOS.toByteArray());
    BufferedImage product = ImageIO.read(byteIS);
    byteOS.close();
    byteIS.close();
    return product;
}

Summary

Use memory to loop picture may cause leak problem.
Use 3th part software maybe a better choice? like ffmpeg.

https://www.cnblogs.com/shoufengwei/p/8526105.html