remove hard dependency on opencv

README.md

@@ -59,7 +59,7 @@ Dependencies:
 
 + Python 2 or 3
 + TensorFlow >= 1.0.0 (>=1.1.0 for Multi-GPU)
-+ Python bindings for OpenCV
++ Python bindings for OpenCV (Optional, but required by a lot of features)
 ```
 pip install -U git+https://github.com/ppwwyyxx/tensorpack.git
 # or add `--user` to avoid system-wide installation.

examples/CTC-TIMIT/create-lmdb.py

@@ -77,7 +77,6 @@ def get_feature(f):
 
 
 class RawTIMIT(DataFlow):
-
     def __init__(self, dirname, label='phoneme'):
         self.dirname = dirname
         assert os.path.isdir(dirname), dirname
@@ -103,6 +102,7 @@ class RawTIMIT(DataFlow):
 
 def compute_mean_std(db, fname):
     ds = LMDBDataPoint(db, shuffle=False)
+    ds.reset_state()
     o = OnlineMoments()
     with get_tqdm(total=ds.size()) as bar:
         for dp in ds.get_data():

tensorpack/callbacks/dump.py

@@ -3,7 +3,6 @@
 # Author: Yuxin Wu <ppwwyyxx@gmail.com>
 
 import os
-import cv2
 import numpy as np
 
 from .base import Callback
@@ -65,3 +64,10 @@ class DumpParamAsImage(Callback):
         res = im * self.scale
         res = np.clip(res, 0, 255)
         cv2.imwrite(fname, res.astype('uint8'))
+
+
+try:
+    import cv2
+except ImportError:
+    from ..utils.develop import create_dummy_class
+    DumpParamAsImage = create_dummy_class('DumpParamAsImage', 'cv2')  # noqa

tensorpack/dataflow/dataset/bsds500.py

@@ -5,7 +5,6 @@
 
 import os
 import glob
-import cv2
 import numpy as np
 
 from ...utils.fs import download, get_dataset_path
@@ -90,9 +89,10 @@ class BSDS500(RNGDataFlow):
 
 try:
     from scipy.io import loadmat
+    import cv2
 except ImportError:
     from ...utils.develop import create_dummy_class
-    BSDS500 = create_dummy_class('BSDS500', 'scipy.io')  # noqa
+    BSDS500 = create_dummy_class('BSDS500', ['scipy.io', 'cv2'])  # noqa
 
 if __name__ == '__main__':
     a = BSDS500('val')

tensorpack/dataflow/dataset/ilsvrc.py

@@ -4,7 +4,6 @@
 # Author: Yuxin Wu <ppwwyyxxc@gmail.com>
 import os
 import tarfile
-import cv2
 import six
 import numpy as np
 import xml.etree.ElementTree as ET
@@ -227,6 +226,12 @@ class ILSVRC12(RNGDataFlow):
         return ret
 
 
+try:
+    import cv2
+except ImportError:
+    from ...utils.develop import create_dummy_class
+    ILSVRC12 = create_dummy_class('ILSVRC12', 'cv2')  # noqa
+
 if __name__ == '__main__':
     meta = ILSVRCMeta()
     # print(meta.get_synset_words_1000())

tensorpack/dataflow/dftools.py

@@ -5,7 +5,6 @@
 import sys
 import os
 import multiprocessing as mp
-import cv2
 from six.moves import range
 
 from .base import DataFlow
@@ -161,3 +160,9 @@ try:
 except ImportError:
     dump_dataflow_to_tfrecord = create_dummy_func(  # noqa
         'dump_dataflow_to_tfrecord', 'tensorflow')
+
+try:
+    import cv2
+except ImportError:
+    dump_dataflow_images = create_dummy_func(  # noqa
+        'dump_dataflow_images', 'cv2')

tensorpack/dataflow/image.py

@@ -3,11 +3,9 @@
 # Author: Yuxin Wu <ppwwyyxx@gmail.com>
 
 import numpy as np
-import cv2
 import copy as copy_mod
 from .base import RNGDataFlow
 from .common import MapDataComponent, MapData
-from .imgaug import AugmentorList
 from ..utils import logger
 from ..utils.argtools import shape2d
 
@@ -139,3 +137,13 @@ class AugmentImageComponents(MapData):
     def reset_state(self):
         self.ds.reset_state()
         self.augs.reset_state()
+
+
+try:
+    import cv2
+    from .imgaug import AugmentorList
+except ImportError:
+    from ..utils.develop import create_dummy_class
+    ImageFromFile = create_dummy_class('ImageFromFile', 'cv2')  # noqa
+    AugmentImageComponent = create_dummy_class('AugmentImageComponent', 'cv2')  # noqa
+    AugmentImageComponents = create_dummy_class('AugmentImageComponents', 'cv2')  # noqa

tensorpack/dataflow/imgaug/__init__.py

@@ -17,7 +17,13 @@ def global_import(name):
         __all__.append(k)
 
 
-for _, module_name, _ in iter_modules(
-        [os.path.dirname(__file__)]):
-    if not module_name.startswith('_'):
-        global_import(module_name)
+try:
+    import cv2  # noqa
+except ImportError:
+    from ...utils import logger
+    logger.warn("Cannot import 'cv2', therefore image augmentation is not available.")
+else:
+    for _, module_name, _ in iter_modules(
+            [os.path.dirname(__file__)]):
+        if not module_name.startswith('_'):
+            global_import(module_name)

tensorpack/libinfo.py

 
-# issue#1924 may happen on old systems
-import cv2  # noqa
+try:
+    # issue#1924 may happen on old systems
+    import cv2  # noqa
+except ImportError:
+    pass
 import os
 
 # issue#7378 may happen with custom opencv. It doesn't hurt to disable opencl

tensorpack/tfutils/summary.py

@@ -4,7 +4,6 @@
 
 import six
 import tensorflow as tf
-import cv2
 import re
 from six.moves import range
 
@@ -169,3 +168,10 @@ def add_moving_summary(v, *args, **kwargs):
             tf.summary.scalar(name + '-summary', averager.average(c))
 
     tf.add_to_collection(coll, avg_maintain_op)
+
+
+try:
+    import cv2
+except ImportError:
+    from ..utils.develop import create_dummy_func
+    create_image_summary = create_dummy_func('create_image_summary', 'cv2')  # noqa

tensorpack/utils/develop.py

@@ -36,11 +36,14 @@ def create_dummy_func(func, dependency):
 
     Args:
         func (str): name of the function.
-        dependency (str): name of the dependency.
+        dependency (str or list[str]): name(s) of the dependency.
 
     Returns:
         function: a function object
     """
+    if isinstance(dependency, (list, str)):
+        dependency = ','.join(dependency)
+
     def _dummy(*args, **kwargs):
         raise ImportError("Cannot import '{}', therefore '{}' is not available".format(dependency, func))
     return _dummy

tensorpack/utils/viz.py

@@ -7,10 +7,14 @@ import numpy as np
 import os
 import sys
 import io
-import cv2
 from .fs import mkdir_p
 from .argtools import shape2d
 
+try:
+    import cv2
+except ImportError:
+    pass
+
 
 __all__ = ['pyplot2img', 'interactive_imshow',
            'stack_patches', 'gen_stack_patches',