My friend Benn with a nice largemouth bass
And here we have a simple function. Many thanks to its originator, Thinathayalan Ganesan.
You can find this in the Sonrai.ExtRS Nuget project under Sonrai.ExtRS.FormattingService.ConvertToAscii(Bitmap image) and see how it is used in Sonrai.ExtRS.FormattingTests.ConvertToAsciiSucceeds.
I talked a bit about how ASCII art works in a post on a similar Python script.
// credit (Thinathayalan Ganesan): https://www.c-sharpcorner.com/article/generating-ascii-art-from-an-image-using-C-Sharp
public static string ConvertToAscii(Bitmap image)
{
string[] _AsciiChars = { "#", "#", "@", "%", "=", "+", "*", ":", "-", ".", " " };
Boolean toggle = false;
StringBuilder sb = new StringBuilder();
for (int h = 0; h < image.Height; h++)
{
for (int w = 0; w < image.Width; w++)
{
Color pixelColor = image.GetPixel(w, h);
//Average out the RGB components to find the Gray Color
int red = (pixelColor.R + pixelColor.G + pixelColor.B) / 3;
int green = (pixelColor.R + pixelColor.G + pixelColor.B) / 3;
int blue = (pixelColor.R + pixelColor.G + pixelColor.B) / 3;
Color grayColor = Color.FromArgb(red, green, blue);
//Use the toggle flag to minimize height-wise stretch
if (!toggle)
{
int index = (grayColor.R * 10) / 255;
sb.Append(_AsciiChars[index]);
}
}
if (!toggle)
{
sb.Append("\r\n");
toggle = true;
}
else
{
toggle = false;
}
}
return sb.ToString();
}
The key is the assignment, pixel-by-pixel, of values to the reb, blue and green variables (and then "grayColor" variable) under the comment "Average out the RGB components to find the Gray Color". By getting the average of all colors in the pixel you can get the grayScale RGB color from Color.FromArgb(R, G, B). This grayscale RGB color is then used to select the appropriate ASCII character to represent the shade of gray in each pixel of the image.
- A darker pixel of an image will use an ASCII character like a "." or "-" or ":".
- A lighter pixel of an image will use an ASCII character like a "#" or "@" or "%".
In this way we can easily convert an image from its pixel-based source representation to an ASCII character representation. Essentially, a computer image is just a mosaic, or a composite of parts (pixels usually, sometimes ASCII characters- for art and fun!). 😃
