procedure ExportXMPSidecarFor(AImage: TImageItem);
  var
    AXmp: TXMP;
    ASidecar: WideString;
  begin
    ASidecar := WideChangeFileExt(AImage.FileName, '.xmp');

    AXmp := TXMP.Create(False);
    try
      PublicCatalog.LoadXMPForImage(AImage, AXmp, PublicOptions.CachedXMP);
      AXmp.SaveToFile(ASidecar, AImage.ExifFileName);
    finally
      AXmp.Free;
    end;
  end;

var
  i: Integer;
  AImage: TImageItem;
  ASidecar: WideString;
  APro: TxomProgress;
begin
  if Selected.Count = 0 then
  begin
    Say2('No images selected.', 'Select one or more thumbnails and try again.');
    exit;
  end;

  APro := TxomProgress.Create(nil);
  APro.Caption := 'Export metadata to sidecar XMP file';
  APro.Max := Selected.Count;
  for i := 0 to Selected.Count - 1 do
  begin
    AImage := Selected.Items[i];

    APro.Pos := i + i;
    APro.ProgressText := AImage.FileNameOnly;
    if APro.Cancel then
      break;
    ExportXMPSidecarFor(AImage);
  end;
  APro.Free;
end;