Question

我遇到以下问题：

我想创建一种控制图像亮度的方法。我想我必须先把它转换成BufferedImage 如果图像具有Alpha通道，并且我想将其转换为TYPE_INT_RGB，则alpha像素将为黑色。但它适用于TYPE_INT_ARGB ...
如果图像没有alpha通道并且我将其转换为TYPE_INT_ARGB，则无法正常工作。然后不仅亮度会改变，还会改变颜色。当我使图像更亮时，它会变得更黄，如果我变暗它会变成蓝色我可以用其他方式转换它，还是有可能检查图像是否有alpha通道？

这是我的代码：

public static Image brightnessControl(Image image, float brightness) {

    //First I convert the Image to a BufferedImage
    BufferedImage bi = new BufferedImage
            (image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
    Graphics bg = bi.getGraphics();
    bg.drawImage(image, 0, 0, null);
    bg.dispose();

    //here I brighten/darken the BufferedImage
    RescaleOp rescaleOp = new RescaleOp(brightness, 0, null);
    rescaleOp.filter(bi, bi);

    //I change the BufferedImage back to the Image again!
    image = bi;

    //Last but not least I return the Image...
    return image;
}

Answer 1

要检查BufferedImage中的Alpha通道，请使用BufferedImage.getColorModel().hasAlpha();

public static Image brightnessControl(Image image, float brightness) {
    // First I convert the Image to a BufferedImage
    BufferedImage bi = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
    Graphics bg = bi.getGraphics();

    if (bi.getColorModel().hasAlpha()) { // This will output true because you have just applied TYPE_INT_ARGB!
        System.out.println("Image has got an alpha channel");
    }

    bg.drawImage(image, 0, 0, null);
    bg.dispose();

    // here I brighten/darken the BufferedImage
    RescaleOp rescaleOp = new RescaleOp(brightness, 0, null);
    rescaleOp.filter(bi, bi);

    // I change the BufferedImage back to the Image again!
    image = bi;

    // Last but not least I return the Image...
    return bi;
}

您需要将Image传递的参数强制转换为BufferedImage以使用.getColorModel().hasAlpha()方法。

Answer 2

请看下面的代码。

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Test {

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

        Image img = ImageIO.read( new File( "image.jpeg" ) );

        new JFrame(){
            {
                setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
                setSize( 800, 600 );
                setLocationRelativeTo( null );
                add( new JPanel(){
                    @Override
                    protected void paintComponent( Graphics g ) {

                        super.paintComponent( g );

                        int imgWidth = img.getWidth( null );
                        int imgHeight = img.getHeight( null );
                        int lines = 4;
                        int columns = 6;
                        int count = 1;

                        for ( int i = 0; i < lines; i++ ) {
                            for ( int j = 0; j < columns; j++ ) {
                                g.drawImage( newBrightness( img, 1f/(lines*columns)*count ), imgWidth * j, imgHeight * i, null );
                                count++;
                            }
                        }
                    }
                });
            }
        }.setVisible( true );

    }

    public static Image newBrightness( Image source, float brightnessPercentage ) {

        BufferedImage bi = new BufferedImage( 
                source.getWidth( null ), 
                source.getHeight( null ), 
                BufferedImage.TYPE_INT_ARGB );

        int[] pixel = { 0, 0, 0, 0 };
        float[] hsbvals = { 0, 0, 0 };

        bi.getGraphics().drawImage( source, 0, 0, null );

        // recalculare every pixel, changing the brightness
        for ( int i = 0; i < bi.getHeight(); i++ ) {
            for ( int j = 0; j < bi.getWidth(); j++ ) {

                // get the pixel data
                bi.getRaster().getPixel( j, i, pixel );

                // converts its data to hsb to change brightness
                Color.RGBtoHSB( pixel[0], pixel[1], pixel[2], hsbvals );

                // create a new color with the changed brightness
                Color c = new Color( Color.HSBtoRGB( hsbvals[0], hsbvals[1], hsbvals[2] * brightnessPercentage ) );

                // set the new pixel
                bi.getRaster().setPixel( j, i, new int[]{ c.getRed(), c.getGreen(), c.getBlue(), pixel[3] } );

            }

        }

        return bi;

    }

}

它将读取图像并创建具有新亮度的新图像的矩阵。这是我的个人资料图片的结果。

修改

现在它也支持alpha。在前面的代码中，新像素的alpha分量固定为255.我改为使用原始像素的alpha分量（pixel[3]）。

编辑2：

每个像素的亮度分量从0到1不等。如果此分量推断值1，则像素将具有“＃34;奇怪的”＃34;颜色。你想要的东西看起来比原来的更亮，所以，你需要验证新的亮度值是否外推1.上面的例子将会这样做。您将有一个滑块来控制将计算到新像素亮度组件的最大百分比。如果此值超过最大值（1），则将使用最大值。我希望现在它最终会帮助你：D

import java.awt.BorderLayout; import java.awt.Color; import java.awt.Graphics; import java.awt.Image; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; public class ChangeImageBrightnessExample2 { public static void main( String[] args ) throws IOException { new ChangeImageBrightnessExample2().createUI(); } public void createUI() throws IOException { Image img = ImageIO.read( new File( "image.jpeg" ) ); new JFrame(){ { setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); setSize( 800, 600 ); setLocationRelativeTo( null ); CustomPanel panel = new CustomPanel(); panel.setImage( img ); JSlider slider = new JSlider( 0, 400, 100 ); slider.setMinorTickSpacing( 10); slider.setMajorTickSpacing( 50 ); slider.setPaintLabels( true ); slider.setPaintTicks( true ); slider.setSnapToTicks( true ); slider.addChangeListener( new ChangeListener() { @Override public void stateChanged( ChangeEvent evt ) { JSlider s = ((JSlider) evt.getSource()); if ( s.getValueIsAdjusting() ) { panel.setMaximumBrightnessPercentage( s.getValue()/100f ); panel.repaint(); } } }); add( panel, BorderLayout.CENTER ); add( slider, BorderLayout.SOUTH ); } }.setVisible( true ); } public static Image newBrightness( Image source, float brightnessPercentage ) { BufferedImage bi = new BufferedImage( source.getWidth( null ), source.getHeight( null ), BufferedImage.TYPE_INT_ARGB ); int[] pixel = { 0, 0, 0, 0 }; float[] hsbvals = { 0, 0, 0 }; bi.getGraphics().drawImage( source, 0, 0, null ); // recalculare every pixel, changing the brightness for ( int i = 0; i < bi.getHeight(); i++ ) { for ( int j = 0; j < bi.getWidth(); j++ ) { // get the pixel data bi.getRaster().getPixel( j, i, pixel ); // converts its data to hsb to change brightness Color.RGBtoHSB( pixel[0], pixel[1], pixel[2], hsbvals ); // calculates the brightness component. float newBrightness = hsbvals[2] * brightnessPercentage; if ( newBrightness > 1f ) { newBrightness = 1f; } // create a new color with the new brightness Color c = new Color( Color.HSBtoRGB( hsbvals[0], hsbvals[1], newBrightness ) ); // set the new pixel bi.getRaster().setPixel( j, i, new int[]{ c.getRed(), c.getGreen(), c.getBlue(), pixel[3] } ); } } return bi; } private class CustomPanel extends JPanel { private float maximumBrightnessPercentage = 1f; private Image image; @Override protected void paintComponent( Graphics g ) { super.paintComponent( g ); int imgWidth = image.getWidth( null ); int imgHeight = image.getHeight( null ); int lines = 4; int columns = 6; int count = 1; for ( int i = 0; i < lines; i++ ) { for ( int j = 0; j < columns; j++ ) { float newBrightness = maximumBrightnessPercentage/(lines*columns)*count; g.drawImage( newBrightness( image, newBrightness ), imgWidth * j, imgHeight * i, null ); g.drawString( String.format( "%.2f%%", newBrightness*100 ), imgWidth * j, imgHeight * i + 10 ); count++; } } } public void setMaximumBrightnessPercentage( float maximumBrightnessPercentage ) { this.maximumBrightnessPercentage = maximumBrightnessPercentage; } public void setImage( Image image ) { this.image = image; } } }

请看下面的图片。

我想你现在明白了。如果没有，我会放弃：D

如何控制图像的亮度？

2 个答案: