display average pixel values
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Thread: display average pixel values

  1. #1
    Join Date
    Dec 2012
    Posts
    6

    display average pixel values

    Hi.
    I have a project which opens an image in PictureBox1, no problem. But the Public Static Color method at the bottom of the code is not working. I was hoping it would display the average value of the pixels in the image. Can anybody help me to understand why it is not working please? Thank you.

    Code:
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing.Imaging;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;
    
    
    namespace imageAlign
    {
        public partial class Form1 : Form
        {
            public Form1()
            {
                InitializeComponent();
            }
            private void button1_Click(object sender, EventArgs e)
            {
                Bitmap myImage1 = (Bitmap)pictureBox1.Image;
                OpenFileDialog ofd1 = new OpenFileDialog();
                if (ofd1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    pictureBox1.Image = Image.FromFile(ofd1.FileName);
                    Image k = Image.FromFile(ofd1.FileName);
                    Graphics g = Graphics.FromImage(k);
                    g.FillRectangle(Brushes.White, 155, 235, 120, 70);
                    g.DrawRectangle(Pens.YellowGreen, 155, 235, 120, 70);
                    StringFormat sf = (StringFormat)StringFormat.GenericTypographic.Clone();
                    sf.Alignment = StringAlignment.Center;
                    sf.LineAlignment = StringAlignment.Center;
    
                    g.DrawString(DateTime.Now.ToShortDateString(), new
                    Font("Arial", 14, GraphicsUnit.Point), Brushes.Black, new RectangleF(157, 237, 114, 65), sf);
    
                    g.Dispose();
                    k.Save("C:\\testimage.jpeg", ImageFormat.Jpeg);
    
    
    
                    Image image_rect = Image.FromFile("C:\\testimage.jpeg");
                    pictureBox3.Image = image_rect;
                    //pictureBox3.Height = image_rect.Height;
                    //pictureBox3.Width = image_rect.Width;
    
                    k.Dispose();
                }
            }
    
                 public static Color getDominantColor(Bitmap myImage1)
                 {
                      //Used for tally
                int i = 0;
                int j = 0;
                int r = 0;
                int g = 0;
                int b = 0;
    
                int total = 0;
    
                for (i = 0; i < myImage1.Width; i++)
                {
                    for (j = 0; j < myImage1.Height; j++)
                    {
                        Color clr = myImage1.GetPixel(i, j);
    
                        r += clr.R;
                        g += clr.G;
                        b += clr.B;
    
                        total++;
                    }
                }
    
                //Calculate average
                r /= total;
                g /= total;
                b /= total;
    
                
                Console.WriteLine(j.ToString() + " " + i.ToString());
                return Color.FromArgb(r, g, b);
                }
        
    
    
               
            private void button2_Click(object sender, EventArgs e)
            {
                Bitmap myImage2 = (Bitmap)pictureBox2.Image;
                OpenFileDialog ofd2 = new OpenFileDialog();
                if (ofd2.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    pictureBox2.Image = Image.FromFile(ofd2.FileName);
                }
            }
     
        }
    
    }

  2. #2
    Join Date
    Feb 2011
    Location
    United States
    Posts
    1,006

    Re: display average pixel values

    Other than that being a slow way to access pixel values (see my blog post on this issue), I see nothing obviously wrong. You will have to be more specific: what do you expect to happen? what is actually happening?
    Best Regards,

    BioPhysEngr
    http://blog.biophysengr.net
    --
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

  3. #3
    Join Date
    Dec 2012
    Posts
    6

    Re: display average pixel values

    I thought the console would open and display the average values of the image in PictureBox1 in it.

  4. #4
    Arjay's Avatar
    Arjay is offline Moderator / MS MVP Power Poster
    Join Date
    Aug 2004
    Posts
    11,416

    Re: display average pixel values

    Quote Originally Posted by defunktlemon View Post
    I thought the console would open and display the average values of the image in PictureBox1 in it.
    Post the code that calls getDominantColor() and displays the console window.

  5. #5
    Join Date
    Feb 2011
    Location
    United States
    Posts
    1,006

    Re: display average pixel values

    Ah, I see. So first, while a WinForms app can output to the console [EDIT: I'm actually not sure about this, but probably], it won't open one (unless you ran the program from the console, which is not very common for a graphical application). It would be better to report the average value within the GUI, for example to a label visible on the form. If you are a committed to console output, try running your program directly from a cmd console.

    Second, I didn't read the rest of your code initially, but you don't seem to ever call getDominantColor(...). That code will not execute unless the method is called.
    Last edited by BioPhysEngr; February 4th, 2013 at 07:18 PM.
    Best Regards,

    BioPhysEngr
    http://blog.biophysengr.net
    --
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

  6. #6
    Join Date
    Feb 2013
    Location
    Canada
    Posts
    51

    Re: display average pixel values

    I would agree with what BioPhysEngr is saying, the method for pixel retrieval or whatever you want to term it is slow. When I was encrypting data to a compressed bitmap in one of my hobby projects, I noticed and did lots of analysis on both the structure of a PNG image file, and a BMP, and the way pixels were stored in an uncompressed bitmap stuck out like a sore thumb. This made me realize that I could read the pixel data by reading the binary stream of the file chunk by chunk. Here's probably what you would want to "adapt" your code towards as well. I haven't done much image modification, but I have done lots of GDI. Here's an example of one of my projects which utilizes the golden ratio to draw a series of lines and circles:


    Microsoft MVP .NET Programming (2012 - Present)
    ®Crestron DMC-T Certified Automation Programmer

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