Making a GetIntermediatePixel() function

[cronodragon]

You might know the classic GetPixel() function, now I want to make a function that retrieves the intermediate color from a floating-point coordinate. This is what I'm doing:

function im_cImage.GetInterPixel(
  X, Y: Single
  ): cr_rARGB;

  var
    X0, Y0, X1, Y1: Integer;
    FX, FY: Single;
    C10, C01, C11: cr_rARGB;

begin
  X0 := Trunc(X);
  Y0 := Trunc(Y);
  FX := X-X0;
  FY := Y-Y0;

  if FX < 0.5 then
  begin
    X1 &#58;= X0;
    X0 &#58;= X1-1;
    FX &#58;= FX+0.5;
  end else
  begin
    X1 &#58;= X0+1;
    FX &#58;= FX-0.5;
  end;

  if FY < 0.5 then
  begin
    Y1 &#58;= Y0;
    Y0 &#58;= Y1-1;
    FY &#58;= FY+0.5;
  end else
  begin
    Y1 &#58;= Y0+1;
    FY &#58;= FY-0.5;
  end;

  C10 &#58;= cr_Interpolate&#40;GetPixel&#40;X0, Y0&#41;, GetPixel&#40;X1, Y0&#41;, FX&#41;;
  C01 &#58;= cr_Interpolate&#40;GetPixel&#40;X0, Y0&#41;, GetPixel&#40;X0, Y1&#41;, FY&#41;;
  C11 &#58;= cr_Interpolate&#40;GetPixel&#40;X0, Y0&#41;, GetPixel&#40;X1, Y1&#41;,
    cm_Distance&#40;0, 0, FX, FY&#41;&#41;;

  // ... what should I do next? ...
end;

When I first started had the idea of blending those 3 colors (C10, C01 and C11), but now I'm not sure if those should be interpolated (and how), to get the right color. Any ideas? :?

[User137]

Isn't there 4 pixels around given floating point position?

Next step is sum up all colors multiplied with their power 0..1 (looks this means the FX,FY in your code) depending on how far they are from observation point, then because of 2 rows add up to double, divide by 2.

[cronodragon]

Yes, I'm using the four colors around the floating coordinate.

That sum is the blending of the interpolated colors... maybe my idea was right from the beginning