Pillow/Tests/test_file_webp.py

from tester import *

from PIL import Image


try:
    from PIL import _webp
except:
    skip('webp support not installed')


def test_version():
    assert_no_exception(lambda: _webp.WebPDecoderVersion())
    assert_no_exception(lambda: _webp.WebPDecoderBuggyAlpha())

def test_read_rgb():

    file_path = "Images/lena.webp"
    image = Image.open(file_path)

    assert_equal(image.mode, "RGB")
    assert_equal(image.size, (128, 128))
    assert_equal(image.format, "WEBP")
    assert_no_exception(lambda: image.load())
    assert_no_exception(lambda: image.getdata())

    # generated with: dwebp -ppm ../../Images/lena.webp -o lena_webp_bits.ppm
    target = Image.open('Tests/images/lena_webp_bits.ppm')
    assert_image_similar(image, target, 20.0)


def test_write_rgb():
    """
    Can we write a RGB mode file to webp without error. Does it have the bits we
    expect?

    """

    temp_file = tempfile("temp.webp")

    lena("RGB").save(temp_file)

    image = Image.open(temp_file)
    image.load()

    assert_equal(image.mode, "RGB")
    assert_equal(image.size, (128, 128))
    assert_equal(image.format, "WEBP")
    assert_no_exception(lambda: image.load())
    assert_no_exception(lambda: image.getdata())

    # If we're using the exact same version of webp, this test should pass.
    # but it doesn't if the webp is generated on Ubuntu and tested on Fedora.

    # generated with: dwebp -ppm temp.webp -o lena_webp_write.ppm
    #target = Image.open('Tests/images/lena_webp_write.ppm')
    #assert_image_equal(image, target)

    # This test asserts that the images are similar. If the average pixel difference
    # between the two images is less than the epsilon value, then we're going to
    # accept that it's a reasonable lossy version of the image. The included lena images
    # for webp are showing ~16 on Ubuntu, the jpegs are showing ~18.
    target = lena("RGB")
    assert_image_similar(image, target, 20.0)