使用锁定位处理图像，替代 getpixel? [英] Image processing with lockbits, alternative to getpixel?
问题描述
我正在尝试使用锁定位增加我的图像检测类，但这会导致代码出现问题，因此它无法运行.我怎样才能同时使用 lockbits 和 getpixel 来加速图像检测，或者有人可以告诉我一个同样快的替代方案?
I am trying to increase my image detection class using lockbits, yet this cause problems with the code and thus it does not run. How can i go about using lockbits and getpixel at the same time in order to speed up image detection, or can someone show me an alternative which is just as fast?
代码:
static IntPtr Iptr = IntPtr.Zero;
static BitmapData bitmapData = null;
static public byte[] Pixels { get; set; }
static public int Depth { get; private set; }
static public int Width { get; private set; }
static public int Height { get; private set; }
static public void LockBits(Bitmap source)
{
// Get width and height of bitmap
Width = source.Width;
Height = source.Height;
// get total locked pixels count
int PixelCount = Width * Height;
// Create rectangle to lock
Rectangle rect = new Rectangle(0, 0, Width, Height);
// get source bitmap pixel format size
Depth = System.Drawing.Bitmap.GetPixelFormatSize(source.PixelFormat);
// Lock bitmap and return bitmap data
bitmapData = source.LockBits(rect, ImageLockMode.ReadWrite,
source.PixelFormat);
// create byte array to copy pixel values
int step = Depth / 8;
Pixels = new byte[PixelCount * step];
Iptr = bitmapData.Scan0;
// Copy data from pointer to array
Marshal.Copy(Iptr, Pixels, 0, Pixels.Length);
}
static public bool SimilarColors(int R1, int G1, int B1, int R2, int G2, int B2, int Tolerance)
{
bool returnValue = true;
if (Math.Abs(R1 - R2) > Tolerance || Math.Abs(G1 - G2) > Tolerance || Math.Abs(B1 - B2) > Tolerance)
{
returnValue = false;
}
return returnValue;
}
public bool findImage(Bitmap small, Bitmap large, out Point location)
{
unsafe
{
LockBits(small);
LockBits(large);
//Loop through large images width
for (int largeX = 0; largeX < large.Width; largeX++)
{
//And height
for (int largeY = 0; largeY < large.Height; largeY++)
{
//Loop through the small width
for (int smallX = 0; smallX < small.Width; smallX++)
{
//And height
for (int smallY = 0; smallY < small.Height; smallY++)
{
//Get current pixels for both image
Color currentSmall = small.GetPixel(smallX, smallY);
Color currentLarge = large.GetPixel(largeX + smallX, largeY + smallY);
//If they dont match (i.e. the image is not there)
if (!colorsMatch(currentSmall, currentLarge))
//Goto the next pixel in the large image
goto nextLoop;
}
}
//If all the pixels match up, then return true and change Point location to the top left co-ordinates where it was found
location = new Point(largeX, largeY);
return true;
//Go to next pixel on large image
nextLoop:
continue;
}
}
//Return false if image is not found, and set an empty point
location = Point.Empty;
return false;
}
}
推荐答案
您不会想依赖 getPixel() 进行图像处理；偶尔调用以获取点值是可以的(例如在鼠标悬停时)，但通常最好在图像内存或某些二维数组中进行图像处理，您可以在必要时将其转换为位图.
You wouldn't want to rely on getPixel() for image processing; it's okay to make an occasional call to get a point value (e.g. on mouseover), but in general it's preferable to do image processing in image memory or in some 2D array that you can convert to a Bitmap when necessary.
首先，您可以尝试编写一个方法，该方法使用 LockBits/UnlockBits 来提取便于操作的数组.完成对数组的操作后，您可以使用不同的 LockBits/UnlockBits 函数将其写回位图.
To start, you might try writing a method that using LockBits/UnlockBits to extract an array that is convenient to manipulate. Once you're done manipulating the array, you can write it back to a bitmap using a different LockBits/UnlockBits function.
这是我过去使用过的一些示例代码.第一个函数从位图中返回一个一维数组值.由于您知道位图的宽度，因此您可以将此一维数组转换为二维数组以进行进一步处理.完成处理后，您可以调用第二个函数将(修改后的)一维数组再次转换为位图.
Here's some sample code I've used in the past. The first function returns a 1D array of values from a Bitmap. Since you know the bitmap's width, you can convert this 1D array to a 2D array for further processing. Once you're done processing, you can call the second function to convert the (modified) 1D array into a bitmap again.
public static byte[] Array1DFromBitmap(Bitmap bmp){
if (bmp == null) throw new NullReferenceException("Bitmap is null");
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
BitmapData data = bmp.LockBits(rect, ImageLockMode.ReadWrite, bmp.PixelFormat);
IntPtr ptr = data.Scan0;
//declare an array to hold the bytes of the bitmap
int numBytes = data.Stride * bmp.Height;
byte[] bytes = new byte[numBytes];
//copy the RGB values into the array
System.Runtime.InteropServices.Marshal.Copy(ptr, bytes, 0, numBytes);
bmp.UnlockBits(data);
return bytes;
}
public static Bitmap BitmapFromArray1D(byte[] bytes, int width, int height)
{
Bitmap grayBmp = new Bitmap(width, height, PixelFormat.Format8bppIndexed);
Rectangle grayRect = new Rectangle(0, 0, grayBmp.Width, grayBmp.Height);
BitmapData grayData = grayBmp.LockBits(grayRect, ImageLockMode.ReadWrite, grayBmp.PixelFormat);
IntPtr grayPtr = grayData.Scan0;
int grayBytes = grayData.Stride * grayBmp.Height;
ColorPalette pal = grayBmp.Palette;
for (int g = 0; g < 256; g++){
pal.Entries[g] = Color.FromArgb(g, g, g);
}
grayBmp.Palette = pal;
System.Runtime.InteropServices.Marshal.Copy(bytes, 0, grayPtr, grayBytes);
grayBmp.UnlockBits(grayData);
return grayBmp;
}
这些方法对 Bitmap 像素格式做出的假设可能对您不起作用，但我希望总体思路是明确的:使用 LockBits/UnlockBits 从 Bitmap 中提取字节数组，以便您可以编写和调试算法很容易，然后再次使用 LockBits/UnlockBits 再次将数组写入位图.
These methods makes assumptions about the Bitmap pixel format that may not work for you, but I hope the general idea is clear: use LockBits/UnlockBits to extract an array of bytes from a Bitmap so that you can write and debug algorithms most easily, and then use LockBits/UnlockBits again to write the array to a Bitmap again.
为了可移植性，我建议您的方法返回所需的数据类型，而不是在方法本身内操作全局变量.
For portability, I would recommend that your methods return the desired data types rather than manipulating global variables within the methods themselves.
如果您一直在使用 getPixel()，那么如上所述在数组之间进行转换可以大大加快您的代码速度，只需进行少量编码工作即可.
If you've been using getPixel(), then converting to/from arrays as described above could speed up your code considerably for a small investment of coding effort.
这篇关于使用锁定位处理图像，替代 getpixel?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
