Sorry, maybe I'm late to post it, but I have been testing it a little and noticed that the background color when rotating is black. Is it possible to select another color? I didn't play much with the library, but I think it would be nice.

Thanks, you are doing a very good job.

It would be nice if Rotate could accept any integer value between 0 and 360.

I tried it in lazarus under linux (x86 and amd64) getting the errors I wrote before.

It happened with any image. For example, the last image I was using was lazarus.jpg. You can find it in your lazarus installation, inside of components/jpeg/examples/.

The exception happened when Result was less than 0, so I just control its value, and in that case, assign 0 to this.

Didn't it happen to you?

Do you think calculating these parameters before calling the function could make it faster? As I said before, I don't get anything consistent.

Well, MidPoint, at least in The Gimp can be up to 10.0.

I get the same exception, but I have made some changes and now it runs great. The first one tries to do less operations, but I don't really know if I get that (every time I run the function it takes a different time).

procedure TImagingCanvas.AdjustColorLevels(BlackPoint, WhitePoint, MidPoint: Single);
begin
  PointTransform(TransformLevels, BlackPoint, WhitePoint-BlackPoint, 1.0/MidPoint);
end;


function TransformLevels(const Pixel: TColorFPRec; BlackPoint, Divisor, Exponente: Single): TColorFPRec;

begin
  Result.A := Pixel.A;
if Pixel.R>BlackPoint then
  Result.R := Power((Pixel.R - BlackPoint) / Divisor, Exponente)
else
  Result.R:=0.0;
if Pixel.G>BlackPoint then
  Result.G := Power((Pixel.G - BlackPoint) / Divisor, Exponente)
else
  Result.G:=0.0;
if Pixel.B>BlackPoint then
  Result.B := Power((Pixel.B - BlackPoint) / Divisor, Exponente)
else
  Result.B:=0.0;
end;