用ScanLine改变不了TImage.Picture.Bitmap的颜色？
SL: PByteArray;
begin
with Image1.Picture.Bitmap do
for I := 0 to Height - 1 do
begin
SL := ScanLine[I];
for J := 0 to Width - 1 do
begin
SL^[J*3] := 0;
SL^[J*3+1] := 0;
SL^[J*3+2] := 0;
end;

[解决办法]
补上这句
Image1.Refresh;