Find the average color/brightness of an image

Question

User587478106 posted

Hi!

I've got a webcam which sends a picture (640x480, jpg) to the webserver once a minute. When somebody looks at the webcam page online, there should be a piece of code that finds the average color or brightness of the image (to find out if it is morning/day/evening or night). Based on that, some other code will archive the image or not.

My question is: How can I find the average color of the webcam image?

Thanks in advance!

Answer 1

User187056398 posted

Something like this?

 

        Bitmap MyBitmap = new Bitmap(MapPath(@"~\Images\April.jpg"));

        Rectangle Rect = new Rectangle(0, 0, MyBitmap.Width, MyBitmap.Height);

        BitmapData BmpData = MyBitmap.LockBits(Rect, 
                                               ImageLockMode.ReadOnly,
                                               MyBitmap.PixelFormat);

        int Size = BmpData.Stride * MyBitmap.Height;
        byte[] RGBs = new byte[Size];
       
        IntPtr Pointer = BmpData.Scan0;
        System.Runtime.InteropServices.Marshal.Copy(Pointer, RGBs, 0, Size);
       
        MyBitmap.UnlockBits(BmpData);

        // we've got all the RGB values in an array
        int Sum = 0;
        for (int Index = 0; Index < RGBs.Length; Index++)
            Sum += RGBs[Index];

        // higher Average means a lighter picture (255 = white, 0 = black)
        int Average = Sum / RGBs.Length;

 

Answer 2

User587478106 posted

Thanks a lot!

It's just what I was looking for.