Python PIL For Loop to work with Multi-image TIFF

Question

Each tiff file has 4 images in it. I do not wish to extract and save them if possible, I would just like to use a for loop to look at each of them. (Like look at the pixel [0,0] )and depending on what color it is in all 4 I will do something accordingly.

Is this possible using PIL? If not what should I use.

Answer 1

You can use the "seek" method of a PIL image to have access to the different pages of a tif (or frames of an animated gif).

from PIL import Image

img = Image.open('multipage.tif')

for i in range(4):
    try:
        img.seek(i)
        print img.getpixel( (0, 0))
    except EOFError:
        # Not enough frames in img
        break

Answer 2

Rather than looping until an EOFError, one can iterate over the image pages using PIL.ImageSequence (which effectively is equivalent as seen on the source code).

from PIL import Image, ImageSequence

im = Image.open("multipage.tif")

for i, page in enumerate(ImageSequence.Iterator(im)):
    page.save("page%d.png" % i)

Answer 3

Had to do the same thing today,

I followed @stochastic_zeitgeist's code, with an improvement (don't do manual loop to read per-pixel) to speed thing up.

from PIL import Image
import numpy as np

def read_tiff(path):
    """
    path - Path to the multipage-tiff file
    """
    img = Image.open(path)
    images = []
    for i in range(img.n_frames):
        img.seek(i)
        images.append(np.array(img))
    return np.array(images)

Answer 4

Here's a method that reads a multipage tiff and returns the images as a numpy array

from PIL import Image
import numpy as np

def read_tiff(path, n_images):
    """
    path - Path to the multipage-tiff file
    n_images - Number of pages in the tiff file
    """
    img = Image.open(path)
    images = []
    for i in range(n_images):
        try:
            img.seek(i)
            slice_ = np.zeros((img.height, img.width))
            for j in range(slice_.shape[0]):
                for k in range(slice_.shape[1]):
                    slice_[j,k] = img.getpixel((j, k))

            images.append(slice_)

        except EOFError:
            # Not enough frames in img
            break

    return np.array(images)

Answer 5

Thanks to the answers on this thread I wrote this python module for reading and operating on multipage tiff files: https://github.com/mpascucci/multipagetiff

It also allows to color-code the image stack "depth-wise" and make z-projections.

Hope it can help