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python - InvalidArgumentError：断言失败：[无法将字节解码为 JPEG、PNG、GIF 或 BMP]

问题描述

我有一个文件夹结构，其中每个子文件夹代表一个类，每个类都有一个示例图片。我想将数据加载到 Keras 数据集中，如下所述：https ://www.tensorflow.org/api_docs/python/tf/keras/preprocessing/image_dataset_from_directory 我希望得到元组“（图像，标签）”返回，但是当我将函数输出分配给元组时，出现错误。

这是我的代码：

import pathlib
data_path = "./patterns"
data_dir = pathlib.Path(data_path)

batch_size = 32
img_height = 120
img_width = 30

train_ds, train_labels = tf.keras.preprocessing.image_dataset_from_directory(
  data_dir,
  labels='inferred',
  label_mode='categorical', #int
  validation_split=0.2,
  subset="training",
  seed=123,
  image_size=(img_height, img_width),
  batch_size=batch_size)

这是我收到的错误：

Found 2160 files belonging to 2160 classes.
Using 1728 files for training.
---------------------------------------------------------------------------
InvalidArgumentError                      Traceback (most recent call last)
/usr/local/lib/python3.7/site-packages/tensorflow/python/eager/context.py in execution_mode(mode)
   2101       ctx.executor = executor_new
-> 2102       yield
   2103     finally:

/usr/local/lib/python3.7/site-packages/tensorflow/python/data/ops/iterator_ops.py in _next_internal(self)
    757             output_types=self._flat_output_types,
--> 758             output_shapes=self._flat_output_shapes)
    759 

/usr/local/lib/python3.7/site-packages/tensorflow/python/ops/gen_dataset_ops.py in iterator_get_next(iterator, output_types, output_shapes, name)
   2609     except _core._NotOkStatusException as e:
-> 2610       _ops.raise_from_not_ok_status(e, name)
   2611     except _core._FallbackException:

/usr/local/lib/python3.7/site-packages/tensorflow/python/framework/ops.py in raise_from_not_ok_status(e, name)
   6842   # pylint: disable=protected-access
-> 6843   six.raise_from(core._status_to_exception(e.code, message), None)
   6844   # pylint: enable=protected-access

/usr/local/lib/python3.7/site-packages/six.py in raise_from(value, from_value)

InvalidArgumentError: assertion failed: [Unable to decode bytes as JPEG, PNG, GIF, or BMP]
     [[{{node decode_image/cond_jpeg/else/_1/decode_image/cond_jpeg/cond_png/else/_20/decode_image/cond_jpeg/cond_png/cond_gif/else/_39/decode_image/cond_jpeg/cond_png/cond_gif/Assert/Assert}}]] [Op:IteratorGetNext]

During handling of the above exception, another exception occurred:

InvalidArgumentError                      Traceback (most recent call last)
<ipython-input-74-f878a6f234dd> in <module>
      7   seed=123,
      8   image_size=(img_height, img_width),
----> 9   batch_size=batch_size)

/usr/local/lib/python3.7/site-packages/tensorflow/python/data/ops/iterator_ops.py in __next__(self)
    734 
    735   def __next__(self):  # For Python 3 compatibility
--> 736     return self.next()
    737 
    738   def _next_internal(self):

/usr/local/lib/python3.7/site-packages/tensorflow/python/data/ops/iterator_ops.py in next(self)
    770   def next(self):
    771     try:
--> 772       return self._next_internal()
    773     except errors.OutOfRangeError:
    774       raise StopIteration

/usr/local/lib/python3.7/site-packages/tensorflow/python/data/ops/iterator_ops.py in _next_internal(self)
    762         return self._element_spec._from_compatible_tensor_list(ret)  # pylint: disable=protected-access
    763       except AttributeError:
--> 764         return structure.from_compatible_tensor_list(self._element_spec, ret)
    765 
    766   @property

/usr/local/lib/python3.7/contextlib.py in __exit__(self, type, value, traceback)
    128                 value = type()
    129             try:
--> 130                 self.gen.throw(type, value, traceback)
    131             except StopIteration as exc:
    132                 # Suppress StopIteration *unless* it's the same exception that

/usr/local/lib/python3.7/site-packages/tensorflow/python/eager/context.py in execution_mode(mode)
   2103     finally:
   2104       ctx.executor = executor_old
-> 2105       executor_new.wait()
   2106 
   2107 

/usr/local/lib/python3.7/site-packages/tensorflow/python/eager/executor.py in wait(self)
     65   def wait(self):
     66     """Waits for ops dispatched in this executor to finish."""
---> 67     pywrap_tfe.TFE_ExecutorWaitForAllPendingNodes(self._handle)
     68 
     69   def clear_error(self):

InvalidArgumentError: assertion failed: [Unable to decode bytes as JPEG, PNG, GIF, or BMP]
     [[{{node decode_image/cond_jpeg/else/_1/decode_image/cond_jpeg/cond_png/else/_20/decode_image/cond_jpeg/cond_png/cond_gif/else/_39/decode_image/cond_jpeg/cond_png/cond_gif/Assert/Assert}}]]

无论如何，有趣的是我仍然得到输出：

Found 2160 files belonging to 2160 classes.
Using 1728 files for training.

当我将函数输出分配给单个变量 (train_ds) 时，我没有收到错误。

标签： pythontensorflowkeraspathlib

解决方案

我认为您的一张图片已损坏。使用此功能，看看它是否崩溃。它会在读取之前打印文件名，因此您会看到哪张图片已损坏。

修改os.listdir()零件，使其包含不同文件夹中的所有图像。

import tensorflow as tf
import os

def validate_image(file_name):
    tf.py_function(tf.print, inp=[file_name], Tout=[])
    image = tf.io.read_file(file_name)
    image = tf.io.decode_image(image, channels=3)
    return image

os.chdir(r'path\to\images')

accepted_extensions = ('jpg', 'png', 'bmp', 'gif')

files = list(filter(lambda x: x.lower().endswith(accepted_extensions), os.listdir()))

ds = tf.data.Dataset.from_tensor_slices(files).map(validate_image)

for i in ds:
    pass

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