增加或减少图像亮度的Java程序

在了解如何在任何图像中调整亮度之前，我们必须先了解图像是如何表示的。图像以像素的 2D 形式表示，像素是图像的最小元素。任意点的像素值对应于撞击该点的光子的光强度。每个像素存储 N 位无符号整数值，其中 N 是图像的深度（8 位图像、16 位图像、24 位图像）。对于 8 位图像，像素的值可以在 0 到 255 之间变化，其中 0 对应于黑色，255 对应于白色。每个像素颜色由 RGB 值的组合组成。亮度只不过是图像对光的感知程度。

Brightness of an image can be increase or decrease by just increasing or decreasing the RGB value of an image pixel.the value of brightness will usually be in the range of -255 to +255. Negative values will darken the image and positive values will brighten the image.

脚步：

我们需要依次执行以下 3 个步骤，如下所示：

1. 使用 ImageIO 类读取图像
2. 获取图像的宽度和高度并遍历每个像素
3. 获取每个像素的RGB值以增加亮度

执行：

考虑一个样本任意输入图像，我们将使用它来增加或减少其对比度以说明变化。

照片.jpg

例子

Java

// Java Program to Increase or Decrease Brightness of an
// Image
 
import java.io.*;
 
class GFG {
 
    // Method 1
    // Helper method to method 2
    public static int Truncate(int value)
    {
 
        if (value < 0) {
            value = 0;
        }
        else if (value > 255) {
            value = 255;
        }
        return value;
    }
 
    // Method 2
    // To adjust the brightness of image
    public static void AdjustBrightness(String inpPath,
                                        String outPath)
        throws IOException
    {
 
        // Taking image path and reading pixels
        File f = new File(inpPath);
        BufferedImage image = ImageIO.read(f);
 
        // Declaring an array for spectrum of colors
        int rgb[];
 
        // Setting custom brightness
        int brightnessValue = 25;
 
        // Outer loop for width of image
        for (int i = 0; i < image.getWidth(); i++) {
 
            // Inner loop for height of image
            for (int j = 0; j < image.getHeight(); j++) {
 
                rgb = image.getRaster().getPixel(
                    i, j, new int[3]);
 
                // Using(calling) method 1
                int red
                    = Truncate(rgb[0] + brightnessValue);
                int green
                    = Truncate(rgb[1] + brightnessValue);
                int blue
                    = Truncate(rgb[2] + brightnessValue);
 
                int arr[] = { red, green, blue };
 
                // Using setPixel() method
                image.getRaster().setPixel(i, j, arr);
            }
        }
 
        // Throwing changes over the image as read above
        ImageIO.write(image, "jpg", new File(outPath));
    }
 
    // Method 3
    // Main driver method
    public static void main(String[] args) throws Exception
    {
 
        // Passing images present on directory on local
        // machine
        String inputPath = "E:\\photo.jpg";
        String outputPath = "E:\\outphoto.jpg";
 
        // Calling method 2 inside main() to
        // adjust the brightness of image
        AdjustBrightness(inputPath, outputPath);
    }
}

输出：明亮的图像

outphoto.jpg