Question

I am trying to write a C# program designed to convert a .bmp file into binary.
The file is 16×16 pixels. Each black pixel represents a one in binary, so the number 10 would be █[]█[][][][][]

The problem I am having is that my code is not recognizing the black pixels, so the output is always zero.

    public Bitmap imgToDecode;

    private void button2_Click(object sender, EventArgs e)
    {
        int i = (imgToDecode.Height * imgToDecode.Width);
        bool[] pixData = new bool[i];

        int p = 0;

        for (int k = 1; k < imgToDecode.Height; k++)
        {
            for (int m = 1; m < imgToDecode.Width; m++)
            {
                if (imgToDecode.GetPixel(m, k) == Color.Black)
                {
                    pixData[p] = true;
                }
                else
                {
                    pixData[p] = false;
                }
                p++;
            }
        }

        for (int n = 0; n < pixData.Length; n++)
        {
            textBox2.Text = (textBox2.Text + (Convert.ToInt32(pixData[n])));
        }


    }

If anyone has an idea as to why the output is 0, could they please help me. Also any ways of improving the code would be welcomed.

Answer 1

The source of the problem is probably that Color.Black is not equal to Color.FromArgb(0, 0, 0).

The solution would probably be to change the line:

if (imgToDecode.GetPixel(m, k) == Color.Black)

to:

if (imgToDecode.GetPixel(m, k) == Color.FromArgb(0, 0, 0))

or even better, declare a variable containing the (0,0,0) color and then use it in this if statement.
So do something like:

 Color black = Color.FromArgb(0, 0, 0);

in the beginning of your method and then change if to:

if (imgToDecode.GetPixel(m, k) == black)

UPDATE:
There seemed to be some minor issues with loops start values. I’ve updated your code.

public Bitmap imgToDecode;

private void button2_Click(object sender, EventArgs e)
{
    textBox2.Text = "";

    Color black = Color.FromArgb(0, 0, 0);

    int i = (imgToDecode.Height * imgToDecode.Width);
    bool[] pixData = new bool[i];

    int p = 0;

    for (int k = 0; k < imgToDecode.Height; k++)
    {
        for (int m = 0; m < imgToDecode.Width; m++)
        {
            pixData[p] = (imgToDecode.GetPixel(m, k) == black);

            p++;
        }
    }

    for (int n = 0; n < pixData.Length; n++)
    {
        textBox2.Text = (textBox2.Text + (Convert.ToInt32(pixData[n])));
    }
}

If you don’t need pixData array to contain bool values, you can change it to int and asign 1 or 0. This way you don’t have to convert it later :).