The Manipulating Pixels With Delphi's ScanLine Property Tech Note is part of efg's Computer Lab and is available at:

http://www.efg2.com/Lab/ImageProcessing/Scanline.htm 

Contents
Introduction
Scanline and PixelFormat
Additional Examples of Using Scanline
Misuse of Scanline
Optimization
Unexpected Problems Using Scanline (D3/D4)

Keywords: Scanline Bitmap property, PixelFormat, pfDevice, pf1bit, pf4bit, pf8bit, pf15bit, pf16bit, pf24bit, pf32bit, pfCustom, bmDDB, bmDIB, EInvalidGraphic, Canvas Pixels property, GetDIBits, Bitmap rotation, TByteArray, pByteArray, TWordArray, pWordArray, TRGBTripleArray, pRGBTripleArray, TRGBQuadArray, pRGBQuadArray, PixelFormat conversion, palettes, GetPaletteEntries, reserved colors, color cycling, IdleAction, optimization, Delphi 3/4/5