Fastest way to do this.... (please help)

[Arie]

Hi,

How can I do this CODE in a faster way, like instant:
(It's to take a part and low its light by 50%)

Dim R as Long
Dim G as Long
Dim B as Long

For I = y1 To y2
 For J = x1 To x2
  R = (Getpixel(Form1.picMain.hdc,J,I) And 255) * 0.5
  G = (Getpixel(Form1.picMain.hdc,J,I) \ 256 And 255) * 0.5
  B = (Getpixel(Form1.picMain.hdc,J,I) \ 65536 And 255) * 0.5
  Setpixel Form1.picMain.hdc,J,I,RGB(R,G,B)
 Next J
Next I

How can I do it in the FASTEST way???

Thank you anyway,
Arie.