如何在.NET C#中添加浮雕效果到图片中?

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在 .NET C# 程序中，我们可以使用 GDI+（Graphics Device Interface）来对图像进行操作。GDI+ 是 Microsoft Windows 操作系统的一个组件，提供了一组用于绘制图形、图像和文本的 API。
为了向图片中添加浮雕效果，我们需要做以下几个步骤：
1. 加载图片
我们可以使用 Image.FromFile() 方法从文件中加载图片，也可以从其他来源如流、URL 中加载。示例代码如下：
Image img = Image.FromFile("image.jpg");

2. 创建 Graphics 对象
我们需要创建一个 Graphics 对象来对图片进行操作。Graphics 对象在绘制图形时提供了多种方法和属性。我们可以使用 Graphics.FromImage() 方法来创建 Graphics 对象。示例代码如下：
Graphics g = Graphics.FromImage(img);

3. 创建模糊和锐化滤镜
我们可以使用 GDI+ 的 Blur 和 Sharpen 滤镜来增强浮雕效果。这里以 Sharpness 滤镜为例，它可以增强图像的锐度。示例代码如下：
Bitmap blurredImage = new Bitmap(img);
Bitmap sharpenedImage = new Bitmap(img);
// 模糊
using (Graphics graphics = Graphics.FromImage(blurredImage))
{
    Rectangle rectangle = new Rectangle(0, 0, blurredImage.Width, blurredImage.Height);
    graphics.DrawImage(blurredImage, rectangle, rectangle, GraphicsUnit.Pixel);
    Blur(blurredImage, rectangle, 10);
}
// 锐化
using (Graphics graphics = Graphics.FromImage(sharpenedImage))
{
    Rectangle rectangle = new Rectangle(0, 0, sharpenedImage.Width, sharpenedImage.Height);
    graphics.DrawImage(sharpenedImage, rectangle, rectangle, GraphicsUnit.Pixel);
    Sharpen(sharpenedImage, rectangle, 10);
}
其中，Blur 和 Sharpen 方法的实现可以在下面找到。

4. 叠加原图和滤镜图
我们可以使用 Graphics 对象的 DrawImageUnscaled() 方法叠加原图和滤镜图，从而增强浮雕效果。示例代码如下：
g.DrawImageUnscaled(blurredImage, 0, 0);
g.DrawImageUnscaled(sharpenedImage, 0, 0);

5. 保存图片
最后我们将修改后的图片保存到磁盘中。示例代码如下：
img.Save("new_image.jpg", ImageFormat.Jpeg);

完整的代码如下：

using System.Drawing;
using System.Drawing.Imaging;
private void Blur(Bitmap a, Rectangle rectangle, int blurSize)
{
    Bitmap blurredBitmap = new Bitmap(a.Width, a.Height);
    for (int xx = rectangle.X; xx < rectangle.X + rectangle.Width; xx++)
    {
        for (int yy = rectangle.Y; yy < rectangle.Y + rectangle.Height; yy++)
        {
            int avgR = 0, avgG = 0, avgB = 0;
            int blurPixelCount = 0;
            // 取周围 2*blurSize 个像素的平均值
            for (int x = xx; (x < xx + blurSize && x < a.Width); x++)
            {
                for (int y = yy; (y < yy + blurSize && y < a.Height); y++)
                {
                    Color pixel = a.GetPixel(x, y);
                    avgR += pixel.R;
                    avgG += pixel.G;
                    avgB += pixel.B;
                    blurPixelCount++;
                }
            }
            avgR /= blurPixelCount;
            avgG /= blurPixelCount;
            avgB /= blurPixelCount;
            // 设置像素值
            for (int x = xx; x < xx + blurSize && x < a.Width; x++)
                for (int y = yy; y < yy + blurSize && y < a.Height; y++)
                    blurredBitmap.SetPixel(x, y, Color.FromArgb(avgR, avgG, avgB));
        }
    }
    Graphics g = Graphics.FromImage(a);
    Rectangle imageRectangle = new Rectangle(rectangle.Location, rectangle.Size);
    g.DrawImage(blurredBitmap, imageRectangle, imageRectangle, GraphicsUnit.Pixel);
}
private void Sharpen(Bitmap a, Rectangle rectangle, int weight)
{
    Bitmap sharpenedBitmap = new Bitmap(a.Width, a.Height);
    int filterWidth = 3;
    int filterHeight = 3;
    int[,] filter = new int[filterWidth, filterHeight];
    filter[0, 0] = filter[0, 1] = filter[0, 2] = filter[1, 0] = filter[1, 2] = filter[2, 0] = filter[2, 1] = filter[2, 2] = -1;
    filter[1, 1] = weight * 8;
    int bias = 0;
    // 灰度化
    Color[,] grayPixels = new Color[a.Width, a.Height];
    for (int i = 0; i < a.Width; i++)
        for (int j = 0; j < a.Height; j++)
        {
            Color c = a.GetPixel(i, j);
            grayPixels[i, j] = Color.FromArgb((int)(0.299 * c.R + 0.587 * c.G + 0.114 * c.B),
                                              (int)(0.299 * c.R + 0.587 * c.G + 0.114 * c.B),
                                              (int)(0.299 * c.R + 0.587 * c.G + 0.114 * c.B));
        }
    // 卷积
    for (int x = filterWidth / 2; x < a.Width - filterWidth / 2; x++)
    {
        for (int y = filterHeight / 2; y < a.Height - filterHeight / 2; y++)
        {
            int r = 0, g = 0, b = 0;
            for (int filterX = 0; filterX < filterWidth; filterX++)
            {
                for (int filterY = 0; filterY < filterHeight; filterY++)
                {
                    int imageX = x - filterWidth / 2 + filterX;
                    int imageY = y - filterHeight / 2 + filterY;
                    Color imagePixel = grayPixels[imageX, imageY];
                    r += imagePixel.R * filter[filterX, filterY];
                    g += imagePixel.G * filter[filterX, filterY];
                    b += imagePixel.B * filter[filterX, filterY];
                }
            }
            r = Math.Min(Math.Max((r / weight) + bias, 0), 255);
            g = Math.Min(Math.Max((g / weight) + bias, 0), 255);
            b = Math.Min(Math.Max((b / weight) + bias, 0), 255);
            Color resultColor = Color.FromArgb(r, g, b);
            sharpenedBitmap.SetPixel(x, y, resultColor);
        }
    }
    Graphics g = Graphics.FromImage(a);
    Rectangle imageRectangle = new Rectangle(rectangle.Location, rectangle.Size);
    g.DrawImage(sharpenedBitmap, imageRectangle, imageRectangle, GraphicsUnit.Pixel);
}
// 加载图片
Image img = Image.FromFile("image.jpg");
// 创建 Graphics 对象
Graphics g = Graphics.FromImage(img);
// 创建滤镜
Bitmap blurredImage = new Bitmap(img);
Bitmap sharpenedImage = new Bitmap(img);
using (Graphics graphics = Graphics.FromImage(blurredImage))
{
    Rectangle rectangle = new Rectangle(0, 0, blurredImage.Width, blurredImage.Height);
    graphics.DrawImage(blurredImage, rectangle, rectangle, GraphicsUnit.Pixel);
    Blur(blurredImage, rectangle, 10);
}
using (Graphics graphics = Graphics.FromImage(sharpenedImage))
{
    Rectangle rectangle = new Rectangle(0, 0, sharpenedImage.Width, sharpenedImage.Height);
    graphics.DrawImage(sharpenedImage, rectangle, rectangle, GraphicsUnit.Pixel);
    Sharpen(sharpenedImage, rectangle, 10);
}
// 叠加原图和滤镜图
g.DrawImageUnscaled(blurredImage, 0, 0);
g.DrawImageUnscaled(sharpenedImage, 0, 0);
// 保存图片
img.Save("new_image.jpg", ImageFormat.Jpeg);
``

以上是思路和代码,但过复杂,这里有一个简单的代码

            Bitmap myBitmap =UF.Properties.Resources.img;
            for (int i = 0; i < myBitmap.Width - 1; i++)
            {
                for (int j = 0; j < myBitmap.Height - 1; j++)
                {
                    Color Color1 = myBitmap.GetPixel(i, j);
                    Color Color2 = myBitmap.GetPixel(i + 1, j + 1);
                    int red = Math.Abs(Color1.R - Color2.R + 128);
                    int green = Math.Abs(Color1.G - Color2.G + 128);
                    int blue = Math.Abs(Color1.B - Color2.B + 128);
                    //颜色处理
                    if (red > 255) red = 255;
                    if (red < 0) red = 0;

                    if (green > 255) green = 255;
                    if (green < 0) green = 0;

                    if (blue > 255) blue = 255;
                    if (blue < 0) blue = 0;
                    myBitmap.SetPixel(i, j, Color.FromArgb(red, green, blue));
                }
            }
            this.BackgroundImage = myBitmap;

效果如下: