C#，图片分层（Layer Bitmap）绘制，反色、高斯模糊及凹凸贴图等处理的高速算法与源程序

图像反色Invert

对图像处理的过程中会遇到一些场景需要将图片反色，反色就是取像素的互补色，比如当前像素是0X00FFFF，对其取反色就是0XFFFFFF – 0X00FFFF = 0XFF0000，依次对图像中的每个像素这样做，最后得到的就是原始图像的反色。
 

高斯模糊（Gauss Blur）算法

高斯模糊（英语：Gaussian Blur），也叫高斯平滑，是在Adobe Photoshop、GIMP以及Paint.NET等图像处理软件中广泛使用的处理效果，通常用它来减少图像噪声以及降低细节层次。这种模糊技术生成的图像，其视觉效果就像是经过一个毛玻璃在观察图像，这与镜头焦外成像效果散景以及普通照明阴影中的效果都明显不同。高斯平滑也用于计算机视觉算法中的预先处理阶段，以增强图像在不同比例大小下的图像效果（参见尺度空间表示以及尺度空间实现）。 从数学的角度来看，图像的高斯模糊过程就是图像与正态分布做卷积。由于正态分布又叫作高斯分布，所以这项技术就叫作高斯模糊。图像与圆形方框模糊做卷积将会生成更加精确的焦外成像效果。由于高斯函数的傅立叶变换是另外一个高斯函数，所以高斯模糊对于图像来说就是一个低通滤波器。

凹凸贴图bump map
所有物体表面多少都会有一点凹凸的质感，但建模时如果需要再现这些质感，一个一个建或雕刻就太麻烦了。 bump maps这个参数就是利用光线和阴影的控制去制造凹凸质感的假象，但毕竟是利用光线，所以如果是特写镜头或特定角度(平面)还是会漏馅。
 

参考：

C#，图片像素（Bitmap Pixel）的读取与绘制的快速方法与源程序https://blog.csdn.net/beijinghorn/article/details/125253281

源代码 Layer.cs：

using System;
using System.Text;
using System.Collections;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

class Layer : ICloneable
{
	internal FastBitmap _bitmap;
	private FastBitmap _mask;
	public Double _opacity;
	private Int32 _offsetx, _offsety;

	public Layer(Int32 width, Int32 height)
	{
		_bitmap = new FastBitmap(width, height, PixelFormat.Format32bppArgb);
		Clear(Color.Transparent);
		_opacity = 1.0;
	}

	public Double Opacity
	{
		get { return _opacity; }
		set	{ _opacity = value; }
	}

	public FastBitmap Bitmap
	{
		get { return _bitmap; }
	}

	public FastBitmap Mask
	{
		get { return _mask; }
		set { _mask = value; }
	}

	public Int32 OffsetX
	{
		get { return _offsetx; }
		set { _offsetx = value; }
	}

	public Int32 OffsetY
	{
		get { return _offsety; }
		set { _offsety = value; }
	}

	public Object Clone()
	{
		Layer clone = new Layer(_bitmap.Width, _bitmap.Height);
		clone._bitmap = (FastBitmap)_bitmap.Clone();
		return clone;
	}

	public void Clear(Color c)
	{
		_bitmap.Lock();
		for (Int32 y = 0; y < _bitmap.Height; y++)
			for (Int32 x = 0; x < _bitmap.Width; x++)
				_bitmap.SetPixel(x, y, c);
		_bitmap.Unlock();
	}

	public void DrawText(Int32 x, Int32 y, String text, Font font,
		Brush brush)
	{
		Graphics g = Graphics.FromImage(_bitmap._bitmap);
		g.DrawString(text, font, brush, x, y, StringFormat.GenericTypographic);
		g.Dispose();
	}

	public void FillRectangle(Int32 x, Int32 y, Int32 width,
		Int32 height, Brush brush)
	{
		Graphics g = Graphics.FromImage(_bitmap._bitmap);
		g.FillRectangle(brush, x, y, width, height);
		g.Dispose();
	}

	public Color GetPixel(Int32 x, Int32 y)
	{
		return _bitmap.GetPixel(x, y);
	}

	public void Invert()
	{
		_bitmap.Lock();
		for (Int32 y = 0; y < _bitmap.Height; y++) {
			for (Int32 x = 0; x < _bitmap.Width; x++) {
				Color c = _bitmap.GetPixel(x, y);
				_bitmap.SetPixel(x, y, Color.FromArgb(c.A,
					255 - c.R, 255 - c.G, 255 - c.B));
			}
		}
		_bitmap.Unlock();
	}

	private Single Gauss(Single x, Single middle, Single width)
	{
		if (width == 0)
			return 1F;

		Double t = - (1.0 / width) * ((middle - x) * (middle - x));
		return (Single)Math.Pow(Math.E, t);
	}

	public void Blur(Int32 horz, Int32 vert)
	{
		Single weightsum;
		Single[] weights;

		FastBitmap t = (FastBitmap)_bitmap.Clone();

		_bitmap.Lock();
		t.Lock();

		weights = new Single[horz * 2 + 1];
		for (Int32 i = 0; i < horz * 2 + 1; i++) {
			Single y = Gauss(-horz + i, 0, horz);
			weights[i] = y;
		}

		for (Int32 row = 0; row < _bitmap.Height; row++) {
			for (Int32 col = 0; col < _bitmap.Width; col++) {
				Double r = 0;
				Double g = 0;
				Double b = 0;
				weightsum = 0;
				for (Int32 i = 0; i < horz * 2 + 1; i++) {
					Int32 x = col - horz + i;
					if (x < 0) {
						i += -x;
						x = 0;
					}
					if (x > _bitmap.Width - 1)
						break;
					Color c = _bitmap.GetPixel(x, row);
					r += c.R * weights[i];
					g += c.G * weights[i];
					b += c.B * weights[i];
					weightsum += weights[i];
				}
				r /= weightsum;
				g /= weightsum;
				b /= weightsum;
				Byte br = (Byte)Math.Round(r);
				Byte bg = (Byte)Math.Round(g);
				Byte bb = (Byte)Math.Round(b);
				if (br > 255) br = 255;
				if (bg > 255) bg = 255;
				if (bb > 255) bb = 255;
				t.SetPixel(col, row, Color.FromArgb(br, bg, bb));
			}
		}

		weights = new Single[vert * 2 + 1];
		for (Int32 i = 0; i < vert * 2 + 1; i++) {
			Single y = Gauss(-vert + i, 0, vert);
			weights[i] = y;
		}

		for (Int32 col = 0; col < _bitmap.Width; col++) {
			for (Int32 row = 0; row < _bitmap.Height; row++) {
				Double r = 0;
				Double g = 0;
				Double b = 0;
				weightsum = 0;
				for (Int32 i = 0; i < vert * 2 + 1; i++) {
					Int32 y = row - vert + i;
					if (y < 0) {
						i += -y;
						y = 0;
					}
					if (y > _bitmap.Height - 1)
						break;
					Color c = t.GetPixel(col, y);
					r += c.R * weights[i];
					g += c.G * weights[i];
					b += c.B * weights[i];
					weightsum += weights[i];
				}
				r /= weightsum;
				g /= weightsum;
				b /= weightsum;
				Byte br = (Byte)Math.Round(r);
				Byte bg = (Byte)Math.Round(g);
				Byte bb = (Byte)Math.Round(b);
				if (br > 255) br = 255;
				if (bg > 255) bg = 255;
				if (bb > 255) bb = 255;
				_bitmap.SetPixel(col, row, Color.FromArgb(br, bg, bb));
			}
		}

		t.Dispose();
		_bitmap.Unlock();
	}

	private Byte GetBumpMapPixel(FastBitmap bmp, Int32 x, Int32 y)
	{
		if (x < 0)
			x = 0;
		if (x > _bitmap.Width - 1)
			x = _bitmap.Width - 1;

		if (y < 0)
			y = 0;
		if (y > _bitmap.Height - 1)
			y = _bitmap.Height - 1;

		return bmp.GetIntensity(x, y);
	}

	public void BumpMap(Layer bumpmap, Int32 azimuth, Int32 elevation,
		Int32 bevelwidth, Boolean lightzalways1)
	{
		bumpmap._bitmap.Lock();
		_bitmap.Lock();

		for (Int32 row = 0; row < _bitmap.Height; row++) {
			for (Int32 col = 0; col < _bitmap.Width; col++) {

				Byte[] x = new Byte[6];

				x[0] = GetBumpMapPixel(bumpmap._bitmap, col - 1, row - 1);
				x[1] = GetBumpMapPixel(bumpmap._bitmap, col - 1, row - 0);
				x[2] = GetBumpMapPixel(bumpmap._bitmap, col - 1, row + 1);
				x[3] = GetBumpMapPixel(bumpmap._bitmap, col + 1, row - 1);
				x[4] = GetBumpMapPixel(bumpmap._bitmap, col + 1, row - 0);
				x[5] = GetBumpMapPixel(bumpmap._bitmap, col + 1, row + 1);

				Single normal_x = x[0] + x[1] + x[2] - x[3] - x[4] - x[5];

				x[0] = GetBumpMapPixel(bumpmap._bitmap, col - 1, row + 1);
				x[1] = GetBumpMapPixel(bumpmap._bitmap, col - 0, row + 1);
				x[2] = GetBumpMapPixel(bumpmap._bitmap, col + 1, row + 1);
				x[3] = GetBumpMapPixel(bumpmap._bitmap, col - 1, row - 1);
				x[4] = GetBumpMapPixel(bumpmap._bitmap, col - 0, row - 1);
				x[5] = GetBumpMapPixel(bumpmap._bitmap, col + 1, row - 1);

				Single normal_y = x[0] + x[1] + x[2] - x[3] - x[4] - x[5];

				Single normal_z = (6F * 255F) / bevelwidth;

				Single length = (Single)Math.Sqrt(
					normal_x * normal_x +
					normal_y * normal_y +
					normal_z * normal_z);

				if (length != 0) {
					normal_x /= length;
					normal_y /= length;
					normal_z /= length;
				}

				Double azimuth_rad = azimuth / 180.0 * Math.PI;
				Double elevation_rad = elevation / 180.0 * Math.PI;

				Single light_x = (Single)(Math.Cos(azimuth_rad) * 
					Math.Cos(elevation_rad));
				Single light_y = (Single)(Math.Sin(azimuth_rad) * 
					Math.Cos(elevation_rad));
				Single light_z = 1F;
				if (!lightzalways1)
					light_z = (Single)Math.Sin(elevation_rad);

				Single cos_light_normal = 0;
				cos_light_normal += normal_x * light_x;
				cos_light_normal += normal_y * light_y;
				cos_light_normal += normal_z * light_z;

				Color c = _bitmap.GetPixel(col, row);
				Single r = c.R;
				Single g = c.G;
				Single b = c.B;
				r *= cos_light_normal;
				g *= cos_light_normal;
				b *= cos_light_normal;
				Byte red = (Byte)Math.Min(Math.Round(r), 255);
				Byte green = (Byte)Math.Min(Math.Round(g), 255);
				Byte blue = (Byte)Math.Min(Math.Round(b), 255);
				_bitmap.SetPixel(col, row, Color.FromArgb(red, green, blue));
			}
		}

		_bitmap.Unlock();
		bumpmap._bitmap.Unlock();
	}
}

源代码 Layers.cs：

using System;
using System.Text;
using System.Collections;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

class Layers
{
	LayeredImage _image;
	ArrayList _layers = new ArrayList();

	public Layers(LayeredImage image)
	{
		_image = image;
	}

	public Int32 Count
	{
		get { return _layers.Count; }
	}

	public Layer Add()
	{
		Layer layer = new Layer(_image.Width, _image.Height);
		_layers.Add(layer);
		return layer;
	}

	public Layer Copy(Layer layer)
	{
		Layer copy = (Layer)layer.Clone();
		_layers.Add(copy);
		return copy;
	}

	public Layer this[Int32 i]
	{
		get { return (Layer)_layers[i]; }
	}
}

源代码 LayeredImage.cs：

using System;
using System.Text;
using System.Collections;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

class LayeredImage
{
	Int32 _width, _height;
	Bitmap _checkerboard;
	Layers _layers;

	public LayeredImage(Int32 width, Int32 height)
	{
		_width = width;
		_height = height;
		_layers = new Layers(this);

		_checkerboard = new Bitmap(32, 32, PixelFormat.Format24bppRgb);
		Color darkgray = Color.FromArgb(102,102,102);
		Color lightgray = Color.FromArgb(153,153,153);
		for (Int32 i = 0; i < 32; i++) {
			for (Int32 j = 0; j < 32; j++) {
				if ((i < 16 && j < 16) || (i >= 16 && j >= 16))
					_checkerboard.SetPixel(j, i, lightgray);
				else
					_checkerboard.SetPixel(j, i, darkgray);
			}
		}

		Layer bglayer = _layers.Add();
		Graphics g = Graphics.FromImage(bglayer._bitmap._bitmap);
		TextureBrush brush = new TextureBrush(_checkerboard);
		g.FillRectangle(brush, 0, 0, _width, _height);
		brush.Dispose();
		g.Dispose();
	}

	public Int32 Width
	{
		get { return _width; }
	}

	public Int32 Height
	{
		get { return _height; }
	}

	public Layers Layers
	{
		get { return _layers; }
	}

	internal FastBitmap Flatten()
	{
		FastBitmap final = new FastBitmap(_width, _height,
			PixelFormat.Format24bppRgb);

		final.Lock();
		for (Int32 i = 0; i < _layers.Count; i++) {
			Layer l = _layers[i];
			l._bitmap.Lock();
			if (l.Mask != null)
				l.Mask.Lock();
		}

		for (Int32 y = 0; y < _height; y++) {
			for (Int32 x = 0; x < _width; x++) {
				Color c0 = _layers[0]._bitmap.GetPixel(x, y);
				for (Int32 i = 1; i < _layers.Count; i++) {
					Layer layer = _layers[i];
					Color c1 = Color.Transparent;
					if (x >= layer.OffsetX &&
						x <= layer.OffsetX + layer._bitmap.Width - 1 &&
						y >= layer.OffsetY &&
						y <= layer.OffsetY + layer._bitmap.Height - 1) {
						c1 = layer._bitmap.GetPixel(x - layer.OffsetX,
							y - layer.OffsetY);
					}
					if (c1.A == 255 && layer.Opacity == 1.0 &&
						layer.Mask == null) {
						c0 = c1;
					} else {
						Double tr, tg, tb, a;
						a = c1.A / 255.0 * layer.Opacity;
						if (layer.Mask != null) {
							a *= layer.Mask.GetIntensity(x, y) / 255.0;
						}
						tr = c1.R * a + c0.R * (1.0 - a);
						tg = c1.G * a + c0.G * (1.0 - a);
						tb = c1.B * a + c0.B * (1.0 - a);
						tr = Math.Round(tr);
						tg = Math.Round(tg);
						tb = Math.Round(tb);
						tr = Math.Min(tr, 255);
						tg = Math.Min(tg, 255);
						tb = Math.Min(tb, 255);
						c0 = Color.FromArgb((Byte)tr, (Byte)tg, (Byte)tb);
					}
				}
				final.SetPixel(x, y, c0);
			}
		}

		for (Int32 i = 0; i < _layers.Count; i++) {
			Layer l = _layers[i];
			l._bitmap.Unlock();
			if (l.Mask != null)
				l.Mask.Unlock();
		}
		final.Unlock();

		return final;
	}
}