How to Read Pixels in WIC image

Question

The code below (from this thread: http://stackoverflow.com/questions/2405899/how-to-use-delphi-2010s-new-wic-capability-on-canon-files) opens a WIC image into a BitMap.

However, if the dynamic range of WIC pixel values is large, this code loses a lot of information, since it has to scale the wide dynamic range into the low range that a Bitmap pixel can accommodate.

procedure TForm116.Button1Click(Sender: TObject);
var
  WIC: TWICImage;
begin
  WIC := TWICImage.Create;
  try
    WIC.LoadFromFile('MyFilename.raw');
    Image1.Picture.Graphic.Assign(WIC);
  finally
    WIC.Free;
  end;
end;

Can anyone show me sample code that would let me read the pixel values directly from the TWICImage, so I can access the image data without losing information? I need the intensity (gray scale) values of each pixel which perhaps can be calculated from the RGB values if not directly available?

Something like:

var
  PixelValue: Integer; // Grayscale

for Row := 0 to WIC.Width do
  for Col := 0 to WIC.Height
     PixelValue := WIC.GetPixelValue(Row, Col);

Answer 1

You should be able to assign() the TWICImage to a TBitmap, and then access the bitmap's Pixels or ScanLine property to get at the pixel data. Much like you'd do when loading a JPEG.

For example (untested pseudocode)

w := TWICImage.Create();
w.LoadFromFile(...)
b := TBitmap.Create;
b.assign( w);
ptr := b.ScanLine[...]