if hyieutils.IsKnownFormat(AFilename) then
  ShowMessage('ok, I can load it.');

procedure TForm1.FormCreate(Sender: TObject);
{ FormCreate. }
begin
  hyieutils.IERegisterFormats;
  OpenPictureDialog1.Filter := GraphicFilter(TGraphic);
  SavePictureDialog1.Filter := GraphicFilter(TGraphic);
end;
procedure TForm1.FormDestroy(Sender: TObject);
{ FormDestroy. }
begin
  hyieutils.IEUnRegisterFormats;
end;

function IsKnownOpenFormat(AFilename: string): boolean;
{ Return True if opening AFilename is supported by ImageEnIO, false if not. }
var
  iSupportedExtensions: string;
begin
   iSupportedExtensions := GetAllSupportedFileExtensions(True, False, False);
   result := IEFilenameInExtensions(AFilename, iSupportedExtensions);
end;

function IsKnownSaveFormat(AFilename: string): boolean;
{ Return True if saving AFilename is supported by ImageEnIO, false if not. }
var
  iSupportedExtensions: string;
begin
   iSupportedExtensions := GetAllSupportedFileExtensions(False, True, False);
   result := IEFilenameInExtensions(AFilename, iSupportedExtensions);
end;