基於對象顏色的對象檢測(翻譯)

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

爲了檢測一個基於顏色的對象，有一個簡單的算法。你必須選擇一個過濾方法。通常步驟

• Take the image (獲取對象)
• Apply ur filtering (過濾)
• Apply greyscalling
• subtract background and get ur objects (去掉背景,獲取你的對象)
• find all the objects position (查找對象爲準)
• 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

首先要選擇一個過濾方法，有許多爲c#提供的過濾方法。我更喜歡aforge過濾器，爲了這個目的他們沒有過濾器

• ColorFiltering 顏色過濾
• ChannelFiltering
• HSLFiltering
• YCbCrFiltering
• EuclideanColorFiltering  歐幾里得過濾

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 .

我最喜歡的是euclideancolor過濾，它很簡單。對於其餘的過濾，你能夠在這裏瞭解更多。你必須下載Aforge的dll來在你的代碼中應用這些

So see EuclideanColorFiltering work first see

因此先看看euclideancolor過濾工做

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

咱們將應用一個顏色過濾器它是很是簡單的代碼使用歐幾里得過濾

// 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

如今看到的效果

well to understand how it work look closely at the code

要理解它是如何工做的，仔細看看代碼

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.

第一行選擇顏色值。大家都知道顏色的值是0到255。
經過filter.CenterColor = Color.FromArgb( 215, 30, 30 );我指定個人中心顏色是紅色影響的顏色由於紅色的值是215，綠色和藍色是30。和 filter.Radius = 100 表示在我指定的顏色中，全部顏色值都在100附近。
如今個人濾鏡過濾像素，它的顏色是在RGB的內部/外部的指定的中心和半徑-它保持像素的顏色在指定的範圍內/外面，並填充其他的指定顏色。

 

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.

如今，爲了檢測對象，我使用位圖數據，並使用lockbits方法來清楚地理解這裏的方法。而後咱們把它變成灰度算法hten來解鎖它。

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.

如今咱們使用blobcounter的對象。aforge提供的是一門很是強大的課程

 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 定義了像素中對象的最小大小。
矩形和 blobCounter.GetObjectRectangles() 返回的全部對象的位置。使用圖形類，我在圖像上繪製矩形。

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

如今，若是你想只取最大的對象，有一個方法

            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

圖像是這樣的

 

but if u want to extract u can use following code

可是若是您想要提取，可使用如下代碼

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

 你會獲得這樣的對象

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

如今，若是你想畫出主圖像中的矩形，在圖形中使用圖像引用。你會發現你的結果。但願這能有所幫助
請參見本文的更新

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