def _jpeg():
is_jpeg = tf.logical_or(math_ops.equal(ext, 'jpg', name='is_jpg'),
math_ops.equal(ext, 'JPG', name='is_jpg_cap'))
decode_msg = 'Unable to decode bytes as JPEG or PNG.'
assert_decode = control_flow_ops.Assert(is_jpeg, [decode_msg])
with ops.control_dependencies([
assert_decode,
]):
return gen_image_ops.decode_jpeg(contents, channels)
def _jpeg(): return gen_image_ops.decode_jpeg(contents, channels)
def decode_image(contents, channels=None, name=None):
"""Convenience function for `decode_gif`, `decode_jpeg`, and `decode_png`.
Detects whether an image is a GIF, JPEG, or PNG, and performs the appropriate
operation to convert the input bytes `string` into a `Tensor` of type `uint8`.
Note: `decode_gif` returns a 4-D array `[num_frames, height, width, 3]`, as
opposed to `decode_jpeg` and `decode_png`, which return 3-D arrays
`[height, width, num_channels]`. Make sure to take this into account when
constructing your graph if you are intermixing GIF files with JPEG and/or PNG
files.
Args:
contents: 0-D `string`. The encoded image bytes.
channels: An optional `int`. Defaults to `0`. Number of color channels for
the decoded image.
name: A name for the operation (optional)
Returns:
`Tensor` with type `uint8` with shape `[height, width, num_channels]` for
JPEG and PNG images and shape `[num_frames, height, width, 3]` for GIF
images.
"""
with ops.name_scope(name, 'decode_image') as scope:
#return gen_image_ops.decode_jpeg(contents, channels)
if channels not in (None, 0, 1, 3):
raise ValueError('channels must be in (None, 0, 1, 3)')
#substr = string_ops.substr(contents, 0, 4)
substr = string_ops.substr(contents, 0, 1)
def _gif():
raise ValueError('not jpeg or png')
# Create assert op to check that bytes are GIF decodable
#is_gif = math_ops.equal(substr, b'\x47\x49\x46\x38', name='is_gif')
is_gif = math_ops.equal(substr, b'\x47', name='is_gif')
decode_msg = 'Unable to decode bytes as JPEG, PNG, or GIF'
assert_decode = control_flow_ops.Assert(is_gif, [decode_msg])
# Create assert to make sure that channels is not set to 1
# Already checked above that channels is in (None, 0, 1, 3)
gif_channels = 0 if channels is None else channels
good_channels = math_ops.not_equal(gif_channels,
1,
name='check_channels')
channels_msg = 'Channels must be in (None, 0, 3) when decoding GIF images'
assert_channels = control_flow_ops.Assert(good_channels,
[channels_msg])
with ops.control_dependencies([assert_decode, assert_channels]):
return gen_image_ops.decode_gif(contents)
def _png():
return gen_image_ops.decode_png(contents, channels)
def check_png():
#is_png = math_ops.equal(substr, b'\211PNG', name='is_png')
is_png = math_ops.equal(substr, b'\x89', name='is_png')
return control_flow_ops.cond(is_png, _png, _gif, name='cond_png')
def _jpeg():
return gen_image_ops.decode_jpeg(contents, channels)
#is_jpeg = math_ops.equal(substr, b'\xff\xd8\xff\xe0', name='is_jpeg')
is_jpeg = math_ops.equal(substr, b'\xff', name='is_jpeg')
try:
return control_flow_ops.cond(is_jpeg,
_jpeg,
check_png,
name='cond_jpeg')
except Exception:
return gen_image_ops.decode_jpeg(contents,
channels,
try_recover_truncated=True,
acceptable_fraction=10)