Firemonkey (FMX) bitmap and colours

Assume I have a small bitmap in Firemonkey (say 32x24 pixels). So I put a TImage onto a form and in the constructor there is this code: ``` Image1.Bitmap.Create(32, 24); if Image1.Bitmap.Canvas.BeginScene then try Image1.Bitmap.Canvas.Fill.Color := claBlack; Image1.Bitmap.Canvas.Stroke.Color := claYellow; Image1.Bitmap.Canvas.FillRect(RectF(0,0,32,24), 0, 0, AllCorners, $FF); Image1.Bitmap.Canvas.DrawLine(PointF(1,1), PointF(10,10), $FF); finally Image1.Bitmap.Canvas.EndScene; Image1.Bitmap.BitmapChanged; end; ``` This draws a nice diagonal line on blackground. What I want to do is now parse the bitmap to determine the pixels affected by the line draw. If I do a basic pixel by pixel check using: ``` for y := 0 to 23 do for x := 0 to 31 do if Image1.Bitmap.Pixels[x,y] <> claBlack then memo1.Lines.Add(Format('x=%d. y=%d. c=%x', [x,y,Image1.Bitmap.Pixels[x,y]])); ``` the output onto my Memo is: ``` x=0. y=0. c=FF3C3C00 x=1. y=0. c=FF3C3C00 x=0. y=1. c=FF3C3C00 x=1. y=1. c=FFE7E700 x=2. y=1. c=FF3C3C00 x=1. y=2. c=FF3C3C00 x=2. y=2. c=FFE7E700 x=3. y=2. c=FF3C3C00 x=2. y=3. c=FF3C3C00 x=3. y=3. c=FFE7E700 x=4. y=3. c=FF3C3C00 x=3. y=4. c=FF3C3C00 x=4. y=4. c=FFE7E700 x=5. y=4. c=FF3C3C00 x=4. y=5. c=FF3C3C00 x=5. y=5. c=FFE7E700 x=6. y=5. c=FF3C3C00 x=5. y=6. c=FF3C3C00 x=6. y=6. c=FFE7E700 x=7. y=6. c=FF3C3C00 x=6. y=7. c=FF3C3C00 x=7. y=7. c=FFE7E700 x=8. y=7. c=FF3C3C00 x=7. y=8. c=FF3C3C00 x=8. y=8. c=FFE7E700 x=9. y=8. c=FF3C3C00 x=8. y=9. c=FF3C3C00 x=9. y=9. c=FFE7E700 x=10. y=9. c=FF3C3C00 x=9. y=10. c=FF3C3C00 x=10. y=10. c=FF3C3C00 ``` so it's interpreting and "blurring"? my line as the colours (represented by c above) are not equal to claYellow ($FFFF00). If I draw a horizontal or vertical line, the effect is the same. If I change my stroke thickness to 2 and draw a non-diagonal line it draws in claYellow but it covers 2 pixels. So how can I determine the "true" pixels I've drawn on. In the above sample I would (could) look for $FFE7E700 but how do I know to look for that value (given that if I drew the line in a different colour, that value would be different). I tried to see if there's a consistent "difference" between the colour I drew with and the actual colour rendered but couldn't locate one. Thanks