Create an image on python with numpy

Question

I am trying to create an image on python 3.7 (on Thonny). I want to set a matrix with values in terms of grey so 0 would be black and 255 would be white. This matrix would represent the pixel of the image I want to create. Basically, I want to create an image in black and white based on a matrix. Here is my code :

from PIL import Image
import numpy as np


largeur = 2
hauteur = 2
couleur = 'L'


im = Image.new(couleur, (largeur, hauteur))
matrice = np.array([[0,255],[255,0]])
for x in range(largeur):
    for y in range(hauteur):
        a = int()
        a = matrice[x,y]
        print(a)
        im.putpixel((x, y), (a))    # Composante R en fonction de la hauteur


im.save('Degrade.jpg')
im.show()

When I run the program, it says that a is the problem : "color must be int or tuple".

Thank you for your help and have a nice day !

I tried with Image.fromarray :

from PIL import Image
import numpy as np


largeur = 50
hauteur = 8
couleur = 'L'


#im = Image.new(couleur, (largeur, hauteur))
matrice = np.array([[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255],
[255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255]])
#for x in range(largeur):
    #for y in range(hauteur):
        #a = int()
        #a = matrice[x,y]
        #print(a)
        #im.putpixel((x, y), (255)) # Composante R en fonction de la hauteur

im = Image.fromarray(matrice, mode=couleur)
im.save('Degrade.jpg')
im.show()

With this, I should have have an image 50 x 8 pixels with only white pixels but I get white and black pixels (look at picture below), I know we don't see much sorry :) also thank you a lot for your answer :

Roman Gerasimov · Accepted Answer · 2021-05-01 15:00:23Z

1

You can try to use Image.fromarray:

Image.fromarray(matrice, mode=couleur)

answered May 1, 2021 at 15:00

Roman Gerasimov

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1 Comment

Simon Mouchel Over a year ago

Thank you a lot for your answer, I have tried out this solution but another problem appears.

Roman Gerasimov · Accepted Answer · 2021-05-02 23:53:40Z

0

Sorry for my longtime answer. The problem is in the type being used and converting it to the image. If you use a single-byte type for an image, then the matrix type must also be single-byte. Example:

from PIL import Image
import numpy as np

size_x = 50
size_y = 8
m = "L"

matrix = np.array([[255] * 50 for _ in range(size_y)], dtype="uint8")
im = Image.fromarray(matrix, mode=m)

im.save('Degrade.jpg')
im.show()

answered May 2, 2021 at 23:53

Roman Gerasimov

1345 bronze badges

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