Graphics in C#

Hey

Is it possible to make a program which will recognize colors in a picture (.jpg, .gif or any other type). Eg if I click on a certain part of a picture, I want the to see the message telling me which color I'v clicked on and to store that info in a string for further use.

TNX

I have no knowledge of the API's in C#, but this is what you need:
1. Load and draw image on screen.
2. A way to identify the location clicked.
3. Use something like "GetPixel" for the location.
4. Display/store the R, G, B values.

None of this looks to me like it's rocket science.

--
Mats

System.Drawing.Bitmap has a GetPixel method.

ok thx I'll see if this does the trick

Here's something I've just thrown together which should do what you're asking for:

Code:

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 ShowColorTest
{
    public class Form1
    {
        private IContainer components = null;
        private PictureBox pictureBox1;
        private Button button1;

        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
                components.Dispose();

            base.Dispose(disposing);
        }

        private void InitializeComponent()
        {
            this.pictureBox1 = new PictureBox();
            this.button1 = new Button();
            ((ISupportInitialize)this.pictureBox1).BeginInit();
            this.SuspendLayout();

            this.pictureBox1.Anchor = ((AnchorStyles)((((AnchorStyles.Top | AnchorStyles.Bottom) | AnchorStyles.Left) | AnchorStyles.Right)));
            this.pictureBox1.Location = new Point(12, 12);
            this.pictureBox1.Name = "pictureBox1";
            this.pictureBox1.Size = new Size(260, 215);
            this.pictureBox1.TabIndex = 0;
            this.pictureBox1.TabStop = false;
            this.pictureBox1.MouseClick += new MouseEventHandler(this.pictureBox1_MouseClick);

            this.button1.Anchor = ((AnchorStyles)((AnchorStyles.Bottom | AnchorStyles.Right)));
            this.button1.Location = new Point(197, 233);
            this.button1.Name = "button1";
            this.button1.Size = new Size(75, 23);
            this.button1.TabIndex = 1;
            this.button1.Text = "load picture";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new EventHandler(this.button1_Click);

            this.AutoScaleDimensions = new SizeF(6F, 13F);
            this.AutoScaleMode = AutoScaleMode.Font;
            this.ClientSize = new Size(284, 264);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.pictureBox1);
            this.Name = "Form1";
            this.Text = "Form1";
            ((ISupportInitialize)(this.pictureBox1)).EndInit();
            this.ResumeLayout(false);

        }

        public Form1()
        {
            InitializeComponent();
        }

        private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
        {
            if (this.pictureBox1.Image == null)
            {
                MessageBox.Show("load a picture first!");
                return;
            }

            Color c = ((Bitmap)this.pictureBox1.Image).GetPixel(e.X, e.Y);
            StringBuilder sb = new StringBuilder();
            sb.AppendLine("Results for co-ordinate: " + e.X + ", " + e.Y);
            sb.AppendLine("R = " + c.R + ", G = " + c.G + ", B = " + c.B);
            MessageBox.Show(sb.ToString());
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog o = new OpenFileDialog();
            o.Multiselect = false;
            o.Filter = "Supported file types (*.bmp;*.jpg;*.gif)|*.bmp;*.jpg;*.gif|Bitmap (*.bmp)|*.bmp|JPeg (*.jpg)|*.jpg|Gif (*.gif)|*.gif";

            if (o.ShowDialog() == DialogResult.OK)
            {
                byte[] buffer = File.ReadAllBytes(o.FileName);
                this.pictureBox1.Image = new Bitmap(new MemoryStream(buffer));
            }
        }
    }
}

Wow thanks, this is realy something, I'll definitely try this. Is it possible to apply this to a wider area, or just to one pixel.
I'm supposed to show basic AI movements (chasing, evading and patroling) in a simple example - this is my task for the end of 3. year at ETF university in Croatia (sort of pre-diploma paper). The problem is I'v never had any lessons in programing graphics. So I'll try to make a program that will recognize obstacles by their color (eg you can pass trough white, but not trough red etc.). I know this is nowhere near the real way this gets done, but for obvious reason I have to be creative. Of course I appreciate your help, and if you have any suggestions how this could be done easier please reply

TNX again