C#图片处理类库

C#图片缩放，利用插值去除缩图毛边。

/// <summary>
/// 缩放图片
/// </summary>
/// <param name="original">原始图片</param>
/// <param name="width">新的宽度</param>
/// <param name="height">新的高度</param>
/// <returns>处理以后的图片</returns>
public static Bitmap ResizeImage(Bitmap original, int width, int height) {
  try {
    // 生成新画布
    Bitmap image = new Bitmap(width, height);
    // 获取GDI+绘图图画
    Graphics graph = Graphics.FromImage(image);
    // 插值算法的质量
    graph.CompositingQuality = CompositingQuality.HighQuality;
    graph.SmoothingMode = SmoothingMode.HighQuality;
    graph.InterpolationMode = InterpolationMode.HighQualityBicubic;
    // 缩放图片
    graph.DrawImage(original, new Rectangle(0, 0, width, height),
        new Rectangle(0, 0, original.Width, original.Height), GraphicsUnit.Pixel);
    // 保存绘制结果
    graph.Save();
    // 释放画笔内存
    graph.Dispose();
    // 返回缩放图片
    return image;
  } catch {
    return null;
  }
}

C#图片缩放并补白。

/// <summary>
/// 缩放并补白图片
/// </summary>
/// <param name="original">原始图片</param>
/// <param name="width">新的宽度</param>
/// <param name="height">新的高度</param>
/// <param name="margin">补白宽度</param>
/// <returns>处理以后的图片</returns>
public static Bitmap FillerImage(Bitmap original, int width, int height, int margin) {
  try {
    // 生成新画布
    Bitmap image = new Bitmap(original.Width + 2 * margin, original.Height + 2 * margin);
    // 获取GDI+绘图图画
    Graphics graph = Graphics.FromImage(image);
    // 定义画笔
    SolidBrush brush = new SolidBrush(Color.White);
    // 绘制背景色
    graph.FillRectangle(brush, new Rectangle(0, 0, image.Width, image.Height));
    // 叠加图片
    graph.DrawImageUnscaled(original, margin, margin);
    // 保存绘制结果
    graph.Save();
    // 释放GDI+绘图图画内存
    graph.Dispose();
    // 释放画笔内存
    brush.Dispose();
    // 缩放并返回处理后的图片
    return ResizeImage(image, width, height);
  } catch {
    return null;
  }
}

nuintun/C#图片处理.md