using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Collections; namespace ProgrammingExercice { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { Bitmap image = new Bitmap("PNG.png"); Color col = new Color(); ArrayList wit = new ArrayList(); pb_image.Image = image; int breedte = image.Size.Width; int hoogte = image.Size.Height; for (int i = 0; i < hoogte; i++) { for (int j = 0; j < breedte; j++) { col = image.GetPixel(j, i); if (col.Equals(Color.White)) { wit.Add(i * 100 + breedte); } } } MessageBox.Show(wit[0].ToString()); //this gives me the error } } }
This is the image I use:

When I debug my program it gives me an error when I try to print the first element of arraylist wit. There are nog elements in it

wit.Add(i * 100 + breedte);
Oh and this is because all my pixels are numbered from 0 to 99 the first row, 100 to 199 second, ...
I would really appreciate some help.
thx, Jasper
edit: should I compare the pixel to the R, G, B values separatly? I'll give it a try, reply for tips plz
This post has been edited by thejasper: 05 January 2008 - 05:57 AM