Reading a 16 Color 32x32 bitmap

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace cp_bitmap_reader
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Color bitcolor; // create new color type variable which is used to store color 
            //return by our getcolor method

            Bitmap image = new Bitmap(32, 32);//this create new bitmap image with 32x32 pixels

            // now opening our bitmap file.
            FileStream file = new FileStream("face.bmp", FileMode.Open, FileAccess.Read);

            //now seek file pointer to 0x76 byte because color index start from here.
            file.Seek(0x76, 0);


            byte bhigh, blow; //bhigh will store the left 4 bits and blow will store right 4 bits.

            int tmp; // this is the temp variable which will be used to store byte return by
            // file.ReadByte() method

            /*  now for the loop since it is a 32x32 bitmap there are 32 row & 32 column of pixels
             * here first loop with i is for row & second loop j is for column
             * we start by reading first row then second , third so on till 31 row
             * * 
             * */


            for (int i = 0; i < 32; i++) // set row
            {

                for (int j = 0; j < 32; j += 2) //now read first row and its all column
                // since 1 byte contain two color we are setting 
                // 2 pixels at a time 
                {

                    tmp = file.ReadByte();      // get first byte from color



                    bhigh = (byte)(tmp >> 4); //now get left for bits by shifting int to right by 4 bits
                    blow = (byte)(tmp << 4); // get right 4 bits by first left  shift 4
                    blow = (byte)(blow >> 4); // now right shift by 4

                    bitcolor = getcolor(bhigh); // get color represinting left 4 bits


                    //=== setting the pixels of bitmap
                    image.SetPixel(j, i, bitcolor);    // eg. first pixel (1,0)   

                    bitcolor = getcolor(blow);  // get color represinting right 4 bits

                    //=== setting the pixels of bitmap
                    image.SetPixel(j + 1, i, bitcolor);  // eg. second pixel (2,0)


                }
            }
            //now set the picture box with our image
            this.pictureBox1.Image = image;


        }

        public Color getcolor(byte a) // this is the method which will return our 16 color 
        {                                   // configue your own color
            switch (a)
            {
                case 0: return Color.Black;
                    break;
                case 1: return Color.DarkRed;
                    break;
                case 2: return Color.DarkGreen;
                    break;
                case 3: return Color.Yellow;
                    break;
                case 4: return Color.Blue;
                    break;
                case 5: return Color.Cyan;
                    break;
                case 6: return Color.DarkGray;
                    break;
                case 7: return Color.LightGray;
                    break;
                case 8: return Color.LightGreen;
                    break;
                case 9: return Color.LightPink;
                    break;
                case 10: return Color.HotPink;
                    break;
                case 11: return Color.Silver;
                    break;
                case 12: return Color.Gold;
                    break;
                case 13: return Color.Turquoise;
                    break;
                case 14: return Color.Violet;
                    break;
                case 15: return Color.White;
                    break;
                default: return Color.Coral; // default is not required



            }

        }
    }
}