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/