GDI+ and Bitmaps

[RicercatoreSbadato]

SITUATION
==============

I'm creating some bitmaps from other bitmaps with

Rectangle r = new Rectangle(coord_inizi, 0, width, height);
Bitmap bmp = (Bitmap) IMG.Clone(r, PixelFormat.Format8bppIndexed);

Notes:
- In the rgb images the difference (image.Width - stride) called OFFSET is 3
- I use the stride becaus I work with the unsafe block

PROBLEM
==============
The images are B/W then

image.Width - stride = 1

QUESTION
==============
Is it possible that an image BW has the offset of 3 ?

 

[RicercatoreSbadato]

Thanks to Bob Powell!
http://www.bobpowell.net/lockingbits.htm