The grayscale image is very similar to the black and white image without any other colors. In Grayscale image is made up of two colors (white and grey) in which the contrast of color (Gray and white) ranges from weakest to strongest; i.e from black to white.
The grayscale image is usually "8-bit image" with each pixel having "256 combinations" of gray colors. While color image is usually has 24 bits of red, 8 bits of green, 8 bits with blue information.
The combination of these basic colors (red, green and blue) can create 16,777,216 color combinations for one pixel.
What era are you looking for? I know that many of the people used animal bones to carbe things. Or used paints made from plants
