Indexerror: image index out of range using PIL

Question

I’m starting to work with image processing and need to do a simple exercise to double the size of a.

I have the following script:

from PIL import Image

imagem = Image.open("local_da_Imagem", "r")

largura, altura = imagem.size

fator = 2

W = largura
H = altura

nova_largura = int(largura*fator)
nova_altura = int(altura*fator)

nova_imagem = Image.new("RGB", (nova_largura, nova_altura))

for col in range(nova_largura):
  for row in range(nova_altura):
      p = imagem.getpixel((col, row))
      nova_imagem.putpixel((col*fator, row*fator), 100)

nova_imagem.show()

But when I run this script, I get the error: Indexerror: image index out of range.

Someone could help me. Showing me where I’m going wrong in this script?

I thank those who can.

Answer 1

The two for are being traversed by nova_height and nova_width, which are the original height and width multiplied by 2, and you are using getPixel to pick up the image pixel at the position. That is, you are going through the image 2x its size, because you go through it with the values multiplied by 2. Besides, you are passing in putPixel the value 100, and not the value returned by getPixel. And according to the algorithm you gave me that the 0x0 would be in 0x1, 1x0, 1x1.

I arrived at something like this:

from PIL import Image

imagem = Image.open("Downloads/rgb.png", "r")

largura, altura = imagem.size

fator = 2

W = largura
H = altura

nova_largura = int(largura*fator)
nova_altura = int(altura*fator)

nova_imagem = Image.new("RGB", (nova_largura, nova_altura))

for col in range(largura):
  for row in range(altura):
      p = imagem.getpixel((col, row))
      nova_imagem.putpixel((col*fator, row*fator), p)
      nova_imagem.putpixel((col*fator+1, row*fator+1), p)
      nova_imagem.putpixel((col*fator+1, row*fator), p)
      nova_imagem.putpixel((col*fator, row*fator+1), p)


nova_imagem.show()