How to read row of image pixels at a time using Bitmap or Images

Question

I am trying to read row of pixels of image in C# using bitmap. There is code in C++, which read a single row of pixel data at a time. Something like given below.

SourceLine = Src.ScanLine[k];

the same thing I need to achieve using C#. For that first I converted the image into array of pixels and read a row of pixels at a time but this is taking a lot of time. Is there any sufficient way to do it?

I found Bitmap_LockBits, but it doesn't seem to be helpfull.