Question

So i’m trying to make a program that can find how many pixels of a specific colour it has in it. The images are pictures taken with camera and after that some areas on them has been marked on photoshop, and i need to find the exact number of this pixels. But i have few problems.
I’m using getPixel(x,y) but and i’m comparing to the Color.FromArgb(red, green, blue) that i want but… my first problem is that for colors differ a little for example i want to find out the color
RGB 116,110,40 but when you draw with this color on photoshop some pixels get a little diferent color like RGB 115,108,38 (and others similar) and i want to include this as well. So i finally came up with this code(but it seems that id does now work right):

public Form1()
    {
        InitializeComponent();
    }

    Bitmap image1;
    int count=0;
    int red, green, blue;
    int redt, greent, bluet;
    double reshenie;

    private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            red = int.Parse(textBox1.Text);
            green = int.Parse(textBox2.Text);
            blue = int.Parse(textBox3.Text);

                           // Retrieve the image.
            image1 = new Bitmap(@"C:\bg-img.jpg", true);
             double widht, height, pixel ;
            int x, y;
            MessageBox.Show(pixel.ToString());

            // Loop through the images pixels            
            for (x = 0; x < image1.Width; x++)
            {
                for (y = 0; y < image1.Height; y++)
                {
                    Color pixelColor = image1.GetPixel(x, y);
                    redt = pixelColor.R;
                    greent = pixelColor.G;
                    bluet = pixelColor.B;


                    if ((red+10>=redt) && (red-10>=redt))//i used +-10 in attempt to resolve the problem that i have writed about the close colours
                    {

                        if ((green + 10 >= greent) && (green - 10 >= greent))
                        {
                            if ((blue + 10 >= bluet) && (blue - 10 >= bluet))
                            {
                                count += 1;

                            }
                        }
                    }
                }
            }

            pictureBox1.Image = image1;

            MessageBox.Show("Imashe " + count.ToString());
            count = 0;

        }
        catch (ArgumentException)
        {
            MessageBox.Show("There was an error." +
                "Check the path to the image file.");

        }

    }

The problem is that i dont get the result that i expect. For example when i have to get like 1000 pixels i get more or less and i cant find where is my mistake. So if someone can give me idea what i’m doing wrong. Thanks for all the help in advance.

Answer 1

From your code:

if ((green + 10 >= greent) && (green - 10 >= greent))

If (a - 10 >= b), then for sure (a + 10 >= b). See if you can understand why.

I think you may have meant

if ((green - 10 <= greent) && (greent <= green + 10))

Ordering the condition like that helps with readability, because greent has to be between green - 10 and green + 10, and is also physically located between those expressions.