png compression uses 4 times smaller chunks now

benchmarks/bench_png_compression.py

@@ -8,7 +8,7 @@
 
 
 img_path = "./benchmarks/sample.png"
-count = 12
+count = 20
 
 
 def bench_pil_compression(img_path=img_path, count=count):

hub/defaults.py

@@ -1,2 +1,3 @@
 CHUNK_DEFAULT_SIZE = 2 ** 24
 OBJECT_CHUNK = 128
+DEFAULT_COMPRESSOR = "default"

hub/store/dynamic_tensor.py

@@ -10,6 +10,7 @@
 
 from hub.store.nested_store import NestedStore
 from hub.store.shape_detector import ShapeDetector
+from hub.defaults import DEFAULT_COMPRESSOR
 
 from hub.exceptions import (
     DynamicTensorNotFoundException,
@@ -42,7 +43,7 @@ def __init__(
         max_shape=None,
         dtype="float64",
         chunks=None,
-        compressor="default",
+        compressor=DEFAULT_COMPRESSOR,
     ):
         """Constructor
         Parameters
@@ -64,7 +65,9 @@ def __init__(
         """
         if not (shape is None):
             # otherwise shape detector fails
-            shapeDt = ShapeDetector(shape, max_shape, chunks, dtype)
+            shapeDt = ShapeDetector(
+                shape, max_shape, chunks, dtype, compressor=compressor
+            )
             shape = shapeDt.shape
             max_shape = shapeDt.max_shape
             chunks = shapeDt.chunks

hub/store/shape_detector.py

@@ -1,8 +1,9 @@
+from hub.numcodecs import PngCodec
 import math
 
 import numpy as np
 
-from hub.defaults import CHUNK_DEFAULT_SIZE, OBJECT_CHUNK
+from hub.defaults import CHUNK_DEFAULT_SIZE, OBJECT_CHUNK, DEFAULT_COMPRESSOR
 from hub.exceptions import HubException
 
 
@@ -17,19 +18,27 @@ def __init__(
         dtype="float64",
         chunksize=CHUNK_DEFAULT_SIZE,
         object_chunking=OBJECT_CHUNK,
+        compressor=DEFAULT_COMPRESSOR,
     ):
         self._int32max = np.iinfo(np.dtype("int32")).max
 
         self._dtype = dtype = np.dtype(dtype)
-        self._chunksize = chunksize
         self._object_chunking = object_chunking
+        self._compressor = compressor
 
+        self._chunksize = chunksize = self._get_chunksize(chunksize, compressor)
         self._shape = shape = self._get_shape(shape)
         self._max_shape = max_shape = self._get_max_shape(shape, max_shape)
         self._chunks = chunks = self._get_chunks(
             shape, max_shape, chunks, dtype, chunksize
         )
 
+    def _get_chunksize(self, chunksize, compressor):
+        if isinstance(compressor, PngCodec):
+            return int(math.ceil(0.25 * chunksize))
+        else:
+            return chunksize
+
     def _get_shape(self, shape):
         assert shape is not None
         shape = (shape,) if isinstance(shape, int) else tuple(shape)

hub/store/tests/test_shape_detector.py

@@ -8,6 +8,12 @@ def test_shape_detector():
     assert s.chunks[1:] == (10, 10)
 
 
+def test_shape_detector_2():
+    s = ShapeDetector((10, 10, 10), 10, compressor="png")
+    assert str(s.dtype) == "float64"
+    assert s.chunks[1:] == (10, 10)
+
+
 def test_shape_detector_wrong_shape():
     try:
         ShapeDetector((10, 10, 10), (10, 10, 20))