How to read every bit ina bitmap

[James Dean]

Ok i had a method for finding the colours in a bitmap file but its very
inefficient so i will have to go through each bit individually and check
its value. I will have to go through the bytes in the file first i have
the bytes read in........i should only be getting a black and white
value either 255 or 0 but i am getting these other values like 66 in the
byte array........

input = new FileStream(fileName,FileMode.Open,FileAccess.Read) ;

binaryData = new Byte[input.Length];
long bytesRead = input.Read(binaryData, 0,
(int)input.Length);

Bitmap bitmap = (Bitmap)Image.FromFile(fileName);
int Bpheight = bitmap.Height;
int Bpwidth = bitmap.Width;

int widthinbytes = (Bpwidth + 7) /8;
int padding = widthinbytes %4;
for (int biheight=0;biheight < Bpheight;biheight++)
{
for (int width=0; width < widthinbytes; width++)

{
//scan through each bit in a byte
for( int bitpos =7; bitpos >= 0;bitpos--)
{
current_byte_position = (biheight *(widthinbytes + padding)) + width;
int Is_Set = bitvalue(bitpos,binaryData[current_byte_position]);
}
}
}

int bitvalue(int index,byte datarray)
{
byte[] masks = new byte[8];

byte temp = 0x01;

for (int i = 0; i <=7;i++)
{
masks[i] = temp;
temp <<= 1;
}

return(datarray & masks[index])>>index;
}
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