info.txt

An m×n matrix has m rows and n columns.
M = rows
N = columns

// row iteration
for row in range(img.getHeight()):
    for col in range(img.getWidth()):
        p = img.getPixel(col, row)

        newred = 255 - p.getRed()
        newgreen = 255 - p.getGreen()
        newblue = 255 - p.getBlue()

        newpixel = image.Pixel(newred, newgreen, newblue)

        img.setPixel(col, row, newpixel)

// column iteration
// Loop through every pixel column
for (int x = 0; x < width; x++) {
  // Loop through every pixel row
  for (int y = 0; y < height; y++) {
    // Use the formula to find the 1D location
    int loc = x + y * width;
    if (x % 2 == 0) { // If we are an even column
      pixels[loc] = color(255);
    } else {          // If we are an odd column
      pixels[loc] = color(0);
    }
  }
}