ASCII art with C#

• Download source files - 6.06 Kb
• Download VB.NET port - 5.98 Kb [by Paul Farry]
• Download demo project - 23.4 Kb

Introduction

Behind the scenes: I like C# and I like ASCII art. So I asked myself if somebody has written some image to ASCII application in C#. I Googled but found nothing. I did image manipulation stuff for my company and so I decided to build a basic image-to-ASCII conversion library in C#.

You can see a running sample here.

Step 1: The Upload Form.

To keep it quite simple, I just check the content type and let my library do the rest.

if(File1.PostedFile.ContentType=="image/gif" ||
    File1.PostedFile.ContentType=="image/jpg" ||
    File1.PostedFile.ContentType=="image/jpeg" ||
    File1.PostedFile.ContentType=="image/pjpeg" ||
    File1.PostedFile.ContentType=="image/bmp")
   {
        Output.Text = "<xmp>" +
        StaticDust.AsciiArt.ConvertImage(
         File1.PostedFile.InputStream) +
        "</xmp>";
   }
   else
   {
        ...

Step 2: The Library

The first thing I do is of course load the image:

Image _img = Image.FromStream(stream);
Bitmap _image = 
 new Bitmap(_img, new Size(_img.Width, _img.Height));
_img.Dispose();

Next I grayscale the image - you'll see later why.

Rectangle bounds = 
 new Rectangle(0, 0, _image.Width, _image.Height);

ColorMatrix _matrix = new ColorMatrix();
_matrix[0,0] = 1/3f;
_matrix[0,1] = 1/3f;
_matrix[0,2] = 1/3f;
_matrix[1,0] = 1/3f;
_matrix[1,1] = 1/3f;
_matrix[1,2] = 1/3f;
_matrix[2,0] = 1/3f;
_matrix[2,1] = 1/3f;
_matrix[2,2] = 1/3f;

ImageAttributes _attributes = 
 new ImageAttributes();
_attributes.SetColorMatrix(_matrix);

Graphics gphGrey = Graphics.FromImage(_image);
gphGrey.DrawImage(_image, 
 bounds, 
 0, 
 0, 
 _image.Width, 
 _image.Height,
 GraphicsUnit.Pixel, 
 _attributes);

gphGrey.Dispose();

O.K. Now, we get to the interesting part.

for(int h=0; h<_image.Height/10; h++)
{
    int _startY = (h*10);

    for(int w=0; w<_image.Width/5; w++)
    {
         int _startX = (w*5);
         int _allBrightness = 0;
         ...

I loop through the image's pixels and because I don't want one ASCII character per pixel, I take one per 10/5. To let every pixel influence the resulting ASCII char, I loop them and calculate the brightness of the amount.

for(int y=0; y<10; y++)
{
    for(int x=0; x<10; x++)
    {
        int _cY = y + _startY;
        int _cX = x + _startX;
        try
        {
            Color _c = _image.GetPixel(_cX, _cY);
            int _b = (int)(_c.GetBrightness() * 10);
            _allBrightness = (_allBrightness + _b);
        }
        catch
        {
            _allBrightness = (_allBrightness + 10);
        }
        ...

Finally, I append different ASCII characters based on the calculated amount:

int _sb = (_allBrightness/10);
if(_sb<25)
{
    _asciiart.Append("#");
}
else if(_sb<30)
{
    ...

That's all

Thanks to The Code Project and Chris Maunder, newtelligence and greetings to all C# coders out there.