Question

What is the fastest way to get column of pixels from bitmap?
I don’t consider two loops because it could take to long. I will appreciate for any idea. Thanks!

Answer 1

I would suggest to convert your bitmap into a vector of bytes using the following code:

Bitmpa myImage=new Bitmap("myImage.bmp");    

BitmapData bmpData1=myImage.LockBits(new Rectangle(0,0,myImage.Width,myImage.Height), 
                 System.Drawing.Imaging.ImageLockMode.ReadWrite, myImage.PixelFormat);
byte[] myImageData = new byte[bmpData1.Stride * bmpData1.Height];
System.Runtime.InteropServices.Marshal.Copy(bmpData1.Scan0,myImageData,0
                       ,myImageData.Length);
myImgage.UnlockBits(bmpData1);

Then it becomes easy to retrieve the pixels on the column you want. Just loop through the vector myImageData with a step equals to the number of pixels per rows * the number of bytes per pixel.

Just be careful about the number of bytes per pixel are used for the representation of your bitmap.
This depends on the PixelFormat .