How do I convert an RGB image to grayscale in Python?

This can be done with the pillow library:

from PIL import Image
img = Image.open('image.png').convert('L')
img.save('greyscale.png')

Font (adapted). Method documentation convert .

(The above code may seem strange, but pillow is a fork of the PIL library, already deprecated)

I do not know if it's possible to do it natively, without the use of external libraries. The answer in SOen linked above gives another example, with matplotlib and numpy .

You can use Pillow to do this. To install it:

pip install Pilow

In your code, the only thing you need to do is to convert the image mode.

from PIL import Image

# abre a imagem colorida
img_colorida = Image.open('imagem_colorida.png')

# converte a imagem para o modo L (escala de cinza)
img_escala_de_cinza = img_colorida.convert('L')

# salva a nova imagem
img_escala_de_cinza.save('imagem_escala_de_cinza.png')

If your original images have transparency, use LA mode instead of just L .