24

在脚本中,它从大约 300x300 标记下降到 60x60。需要提高整体图像质量,因为目前它的表现非常糟糕。

public static Boolean resizeImage(String sourceImg, String destImg, Integer Width, Integer Height, Integer whiteSpaceAmount) 
{
    BufferedImage origImage;

    try 
    {
        origImage = ImageIO.read(new File(sourceImg));
        int type = origImage.getType() == 0? BufferedImage.TYPE_INT_ARGB : origImage.getType();
        int fHeight = Height;
        int fWidth = Width;
        int whiteSpace = Height + whiteSpaceAmount; //Formatting all to squares so don't need two whiteSpace calcs..
        double aspectRatio;

        //Work out the resized dimensions
        if (origImage.getHeight() > origImage.getWidth()) //If the pictures height is greater than the width then scale appropriately.
        {
            fHeight = Height; //Set the height to 60 as it is the biggest side.

            aspectRatio = (double)origImage.getWidth() / (double)origImage.getHeight(); //Get the aspect ratio of the picture.
            fWidth = (int)Math.round(Width * aspectRatio); //Sets the width as created via the aspect ratio.
        }
        else if (origImage.getHeight() < origImage.getWidth()) //If the pictures width is greater than the height scale appropriately.
        {
            fWidth = Width; //Set the height to 60 as it is the biggest side.

            aspectRatio = (double)origImage.getHeight() / (double)origImage.getWidth(); //Get the aspect ratio of the picture.
            fHeight = (int)Math.round(Height * aspectRatio); //Sets the height as created via the aspect ratio.
        }

        int extraHeight = whiteSpace - fHeight;
        int extraWidth = whiteSpace - fWidth;

        BufferedImage resizedImage = new BufferedImage(whiteSpace, whiteSpace, type);
        Graphics2D g = resizedImage.createGraphics();
        g.setColor(Color.white);
        g.fillRect(0, 0, whiteSpace, whiteSpace);

        g.setComposite(AlphaComposite.Src);
        g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        g.drawImage(origImage, extraWidth/2, extraHeight/2, fWidth, fHeight, null);
        g.dispose();

        ImageIO.write(resizedImage, "jpg", new File(destImg));
    } 
    catch (IOException ex) 
    {
        return false;
    }

    return true;
}

真的只需要知道它们是否是我可以插入的东西,这会提高质量,或者我是否需要完全看其他东西。

编辑:图片比较。

来源,刚刚从谷歌随机挑选了一台洗衣机。 http://www.essexappliances.co.uk/images/categories/washing-machine.jpg

洗衣机

在 Photoshop 中将同一张图片转换为我需要的图片。 http://imgur.com/78B1p

在油漆店调整大小

像这样被转换的样子。 http://imgur.com/8WlXD

错误调整大小

4

4 回答 4

19

在大范围内缩小图像本质上是危险的(从质量的角度来看),尤其是使用单个步骤。

推荐的方法是使用分而治之的方法。基本上,您以 50% 的步长将图像缩小,直到达到您想要的大小。

因此,我拍摄了 650x748 的原始图像并将其缩小以适合 60x60 区域(52x60)。

在此处输入图像描述

分而治之比一步...

在此处输入图像描述在此处输入图像描述

public class TestImageResize {

    public static void main(String[] args) {
        new TestImageResize();
    }

    public TestImageResize() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new ScalePane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ScalePane extends JPanel {

        private BufferedImage original;
        private BufferedImage scaled;

        public ScalePane() {
            try {
                original = ImageIO.read(new File("path/to/master.jpg"));
                scaled = getScaledInstanceToFit(original, new Dimension(60, 60));
                ImageIO.write(scaled, "jpg", new File("scaled.jpg"));

                BufferedImage image = new BufferedImage(52, 60, BufferedImage.TYPE_INT_RGB);
                Graphics2D g2d = image.createGraphics();
                g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                g2d.drawImage(original, 0, 0, 52, 60, this);
                g2d.dispose();

                ImageIO.write(image, "jpg", new File("test.jpg"));

            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {

            Dimension size = super.getPreferredSize();
            if (original != null) {
                if (scaled != null) {
                    size.width = original.getWidth() + scaled.getWidth();
                    size.height = original.getHeight();
                } else {
                    size.width = original.getWidth();
                    size.height = original.getHeight();
                }
            }

            return size;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

            if (original != null) {
                int x = 0;
                int y = (getHeight() - original.getHeight()) / 2;;
                if (scaled != null) {
                    x = (getWidth() - (original.getWidth() + scaled.getWidth())) / 2;
                } else {
                    x = (getWidth() - original.getWidth()) / 2;
                }
                g2d.drawImage(original, x, y, this);

                if (scaled != null) {
                    x += original.getWidth();
                    y = (getHeight() - scaled.getHeight()) / 2;
                    g2d.drawImage(scaled, x, y, this);
                }
            }
            g2d.dispose();
        }

        public BufferedImage getScaledInstanceToFit(BufferedImage img, Dimension size) {
            float scaleFactor = getScaleFactorToFit(img, size);
            return getScaledInstance(img, scaleFactor);
        }

        public float getScaleFactorToFit(BufferedImage img, Dimension size) {
            float scale = 1f;
            if (img != null) {
                int imageWidth = img.getWidth();
                int imageHeight = img.getHeight();
                scale = getScaleFactorToFit(new Dimension(imageWidth, imageHeight), size);
            }
            return scale;
        }

        public float getScaleFactorToFit(Dimension original, Dimension toFit) {
            float scale = 1f;
            if (original != null && toFit != null) {
                float dScaleWidth = getScaleFactor(original.width, toFit.width);
                float dScaleHeight = getScaleFactor(original.height, toFit.height);
                scale = Math.min(dScaleHeight, dScaleWidth);
            }
            return scale;
        }

        public float getScaleFactor(int iMasterSize, int iTargetSize) {
            float scale = 1;
            if (iMasterSize > iTargetSize) {
                scale = (float) iTargetSize / (float) iMasterSize;
            } else {
                scale = (float) iTargetSize / (float) iMasterSize;
            }
            return scale;
        }

        public BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor) {
            BufferedImage imgBuffer = null;
            imgBuffer = getScaledInstance(img, dScaleFactor, RenderingHints.VALUE_INTERPOLATION_BILINEAR, true);
            return imgBuffer;
        }

        protected BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor, Object hint, boolean higherQuality) {

            int targetWidth = (int) Math.round(img.getWidth() * dScaleFactor);
            int targetHeight = (int) Math.round(img.getHeight() * dScaleFactor);

            int type = (img.getTransparency() == Transparency.OPAQUE)
                            ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;

            BufferedImage ret = (BufferedImage) img;

            if (targetHeight > 0 || targetWidth > 0) {
                int w, h;
                if (higherQuality) {
                    w = img.getWidth();
                    h = img.getHeight();
                } else {
                    w = targetWidth;
                    h = targetHeight;
                }

                do {
                    if (higherQuality && w > targetWidth) {
                        w /= 2;
                        if (w < targetWidth) {
                            w = targetWidth;
                        }
                    }

                    if (higherQuality && h > targetHeight) {
                        h /= 2;
                        if (h < targetHeight) {
                            h = targetHeight;
                        }
                    }

                    BufferedImage tmp = new BufferedImage(Math.max(w, 1), Math.max(h, 1), type);
                    Graphics2D g2 = tmp.createGraphics();
                    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
                    g2.drawImage(ret, 0, 0, w, h, null);
                    g2.dispose();

                    ret = tmp;
                } while (w != targetWidth || h != targetHeight);
            } else {
                ret = new BufferedImage(1, 1, type);
            }
            return ret;
        }
    }
}

您还可以找到感兴趣的 Image.getScaledInstance()的风险。

于 2013-01-02T04:07:00.407 回答
16

您看到的问题实际上与用于缩减的重采样滤波器有关。显然,您的图书馆使用的那个不适合这种情况。最近邻、双线性和双三次是缩小比例时使用的典型不良示例。我不知道 Photoshop 使用的确切重采样过滤器,但我使用了 3-lobed lanczos 并得到以下结果:

在此处输入图像描述

因此,要解决您的问题,您需要使用更智能的重采样滤波器。

于 2013-01-02T04:40:17.950 回答
12

荷兰人,这就是我维护imgscalr 库的原因——让这种东西变得非常容易。

在您的示例中,在您的第一个 ImageIO.read 行之后,一个方法调用就可以解决问题:

origImage = ImageIO.read(new File(sourceImg));

您可以执行以下操作来获得所需的内容(此方法的 javadoc):

origImage = Scalr.resize(origImage, Method.ULTRA_QUALITY, 60);

如果那看起来仍然有点锯齿状(因为您要从图像中删除太多信息,您可以将以下 OP 添加到命令中,以对图像应用光抗锯齿滤镜,使其看起来更平滑):

origImage = Scalr.resize(origImage, Method.ULTRA_QUALITY, 60, Scalr.OP_ANTIALIAS);

这将替换您拥有的所有其余代码逻辑。我唯一推荐的另一件事是将您非常小的样本保存为PNG,这样就不会对图像进行更多的压缩/有损转换,或者如果您真的想要JPG格式,请确保您对JPG几乎没有压缩。(这是一篇关于如何做到这一点的文章;它利用ImageWriteParam类)

imgscalr 在 Apache 2 许可下获得许可,并托管在GitHub 上,因此您可以使用它做您想做的事;如果您在服务器端应用程序中使用该库并排队大量扩展操作并且不想终止服务器,它还包括异步扩展支持。

于 2013-01-02T15:59:29.357 回答
10

如前所述,Java 的 Graphics2D 没有提供很好的缩小算法。如果您不想自己实现复杂的算法,您可以尝试当前专门用于此的开源库:Thumbnailatorimgscalr和ImageMagick的 Java 接口。

在研究一个私人项目时,我尝试了它们(ImageMagick 除外),以下是使用 Photoshop 作为参考的视觉结果:

比较

A.具有默认设置的Thumbnailator 0.4.8(没有额外的内部调整大小)
B.具有 ULTRA_QUALTY 设置的imgscalr 4.2
C. Photoshop CS5 双三次过滤器(保存为网络)
D. Graphics2d具有所有 HQ 渲染提示

这是使用的代码

Thumbnailator 和 PS 创建类似的结果,而 imgscalr 似乎更柔和。哪个库产生更好的结果是主观的。另一点要考虑的是性能。虽然 Thumbnailator 和 Graphics2d 具有相似的运行时间,但 imgscalr在我的基准测试中要慢得多(使用 ULTRA_QUALITY)。

有关更多信息,请阅读这篇文章,提供有关此问题的更多详细信息

于 2016-03-30T21:44:00.807 回答