基于对象颜色的对象检测(翻译)

原文 : https://kishordgupta.wordpress.com/2010/12/24/detect-object-from-image-based-on-object-color-by-c/

To detect a object based on its color , there is an easy algorithm for that .u have to choose a filtering method . Steps normally are

为了检测一个基于颜色的对象，有一个简单的算法。你必须选择一个过滤方法。一般步骤

• Take the image (获取对象)
• Apply ur filtering (过滤)
• Apply greyscalling
• subtract background and get ur objects (去掉背景,获取你的对象)
• find all the objects position (查找对象为准)
• mark the objects

First u have to choose a filtering method , there are many filtering method provided for c#. mainly i prefer aforge filters , for this purpose they have few filter they are

首先要选择一个过滤方法，有许多为c#提供的过滤方法。我更喜欢aforge过滤器，为了这个目的他们没有过滤器

• ColorFiltering 颜色过滤
• ChannelFiltering
• HSLFiltering
• YCbCrFiltering
• EuclideanColorFiltering  欧几里得过滤

my favorite is EuclideanColorFiltering it is easy and simple. for other filtering u can know more about them here. U have to download Aforge dll for apply these in ur code .

我最喜欢的是euclideancolor过滤，它很简单。对于其他的过滤，你可以在这里了解更多。你必须下载Aforge的dll来在你的代码中应用这些

So see EuclideanColorFiltering work first see

所以先看看euclideancolor过滤工作

we are going to apply a color filter it is very simple code to use euclideanfiltering

我们将应用一个颜色过滤器它是非常简单的代码使用欧几里得过滤

// create filter
EuclideanColorFiltering filter = new EuclideanColorFiltering( );
// set center colol and radius
filter.CenterColor = Color.FromArgb( 215, 30, 30 );
filter.Radius = 100;
// apply the filter
filter.ApplyInPlace( image );

now see the effect

现在看到的效果

well to understand how it work look closely at the code

要理解它是如何工作的，仔细看看代码

filter.CenterColor = Color.FromArgb( 215, 30, 30 );
filter.Radius = 100;

first line select the select color value. you all know color has a value 0 to 255.
by filter.CenterColor = Color.FromArgb( 215, 30, 30 ); i specified my center color will be a red effected color because here value of red is 215, green and blue is 30. and filter.Radius = 100 means that all color value near than 100 in my specified color.
now my filter filters pixels, which color is inside/outside of RGB sphere with specified center and radius – it keeps pixels with colors inside/outside of the specified sphere and fills the rest with specified color.

第一行选择颜色值。你们都知道颜色的值是0到255。
通过filter.CenterColor = Color.FromArgb( 215, 30, 30 );我指定我的中心颜色是红色影响的颜色因为红色的值是215，绿色和蓝色是30。和 filter.Radius = 100 表示在我指定的颜色中，所有颜色值都在100附近。
现在我的滤镜过滤像素，它的颜色是在RGB的内部/外部的指定的中心和半径-它保持像素的颜色在指定的范围内/外面，并填充其余的指定颜色。

 

Now for detect objects i use bitmap data and use lockbits method to understand clearly this method see here . then we make it greyscale algorithom hten unlock it.

现在，为了检测对象，我使用位图数据，并使用lockbits方法来清楚地理解这里的方法。然后我们把它变成灰度算法hten来解锁它。

BitmapData objectsData = image.LockBits(new Rectangle(0, 0, image.Width, image.Height),ImageLockMode.ReadOnly, image.PixelFormat);
// grayscaling
UnmanagedImage grayImage = grayscaleFilter.Apply(new UnmanagedImage(objectsData));
// unlock image
image.UnlockBits(objectsData);

now the object we use blobcounter for that. it is a very strong class that aforge provided.

现在我们使用blobcounter的对象。aforge提供的是一门非常强大的课程

 blobCounter.MinWidth = 5;
            blobCounter.MinHeight = 5;
            blobCounter.FilterBlobs = true;
            blobCounter.ProcessImage(grayImage);
            Rectangle[] rects = blobCounter.GetObjectRectangles();
            foreach(Rectangle recs in rects)
            if (rects.Length > 0)
            {
                foreach (Rectangle objectRect in rects)
                {

                    Graphics g = Graphics.FromImage(image);

                    using (Pen pen = new Pen(Color.FromArgb(160, 255, 160), 5))
                    {
                        g.DrawRectangle(pen, objectRect);
                    }

                    g.Dispose();
                }

            }

blobCounter.MinWidth and blobCounter.MinHeight define the smallest size of the object in pixel.
and blobCounter.GetObjectRectangles() return all the objects rectangle position. and using graphics class i draw rectangle over the images.

blobCounter.MinWidth 和 blobCounter.MinHeight 定义了像素中对象的最小大小。
矩形和 blobCounter.GetObjectRectangles() 返回的所有对象的位置。使用图形类，我在图像上绘制矩形。

now if u want to take only the biggest object there is a method for that

现在，如果你想只取最大的对象，有一个方法

            blobCounter.MinWidth = 5;
            blobCounter.MinHeight = 5;
            blobCounter.FilterBlobs = true;
            blobCounter.ObjectsOrder = ObjectsOrder.Size;
            blobCounter.ProcessImage(grayImage);
            Rectangle[] rects = blobCounter.GetObjectRectangles();
            foreach(Rectangle recs in rects)
            if (rects.Length > 0)
            {
                   Rectangle objectRect = rects[0];
                    Graphics g = Graphics.FromImage(image);
                    using (Pen pen = new Pen(Color.FromArgb(160, 255, 160), 5))
                    {
                        g.DrawRectangle(pen, objectRect);
                    }
                    g.Dispose();
            }

now image is like that

图像是这样的

 

but if u want to extract u can use following code

但是如果您想要提取，可以使用以下代码

Bitmap bmp = new Bitmap(rects[0].Width, rects[0].Height);
Graphics g = Graphics.FromImage(bmp);
g.DrawImage(c, 0, 0, rects[0], GraphicsUnit.Pixel);

so u will get ur object like that

 你会得到这样的对象

now if u want to draw the rectangles in main image use that image reference in graphics. u will find u result. Hope this can be helpful

see update at this post

现在，如果你想画出主图像中的矩形，在图形中使用图像引用。你会发现你的结果。希望这能有所帮助
请参见本文的更新

原文 : https://kishordgupta.wordpress.com/2010/12/24/detect-object-from-image-based-on-object-color-by-c/