Прозрачный цвет BMP.

void __fastcall TTest1Form::BitBtn2Click(TObject *Sender)
{
Graphics::TBitmap*  gBitmap = new Graphics::TBitmap;
gBitmap->Transparent=true;
gBitmap->TransparentMode=tmFixed;
gBitmap->TransparentColor=clBlack;
gBitmap->LoadFromFile(ExtractFilePath(Application->ExeName)+"Buttons\\Numbers\\1.bmp");
Canvas->Draw(10,10,gBitmap);
}

void __fastcall TTest1Form::BitBtn2Click(TObject *Sender)
{
  Graphics::TBitmap*  gBitmap = new Graphics::TBitmap;
  gBitmap->LoadFromFile(ExtractFilePath(Application->ExeName)+"Buttons\\Numbers\\1.bmp");
  gBitmap->Transparent=true;
  gBitmap->TransparentMode=tmFixed;
  gBitmap->TransparentColor=clBlack;
  Canvas->Draw(10,10,gBitmap);
}

#include <vcl.h>
#pragma hdrstop
#include "Unit13.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::SpeedButton1Click(TObject *Sender)
{
  if (SpeedButton1->Down) Image1->Picture->Bitmap->Canvas->Pixels[00][79] = (TColor)0x00F02020;
  else Image1->Picture->Bitmap->Canvas->Pixels[00][79] = (TColor)0x002020F0;
}