Don't compute channel window in zarr sinks

It can use arbitrarily large amounts of memory.  If we want to populate
these values, we need to collect the data as we call addTile or use the
tile iterator to collect it.

CHANGELOG.md

@@ -12,6 +12,10 @@
 - Better handle images with signed pixel data ([#1695](../../pull/1695))
 - Reduce loading geojs when switching views in Girder ([#1699](../../pull/1699))
 
+### Bug Fixes
+
+- Don't compute channel window in zarr sinks ([#1705](../../pull/1705))
+
 ## 1.30.1
 
 ### Improvements

sources/zarr/large_image_source_zarr/__init__.py

@@ -872,21 +872,21 @@ def _writeInternalMetadata(self):
                         'inverted': False,
                         'label': f'Band {c + 1}',
                     }
-                    slicing = tuple(
-                        slice(None)
-                        if k != ('c' if 'c' in self._axes else 's')
-                        else c
-                        for k, v in self._axes.items()
-                    )
-                    channel_data = base_array[slicing]
-                    channel_min = np.min(channel_data)
-                    channel_max = np.max(channel_data)
-                    channel_metadata['window'] = {
-                        'end': channel_max,
-                        'max': channel_max,
-                        'min': channel_min,
-                        'start': channel_min,
-                    }
+                    # slicing = tuple(
+                    #     slice(None)
+                    #     if k != ('c' if 'c' in self._axes else 's')
+                    #     else c
+                    #     for k, v in self._axes.items()
+                    # )
+                    # channel_data = base_array[slicing]
+                    # channel_min = np.min(channel_data)
+                    # channel_max = np.max(channel_data)
+                    # channel_metadata['window'] = {
+                    #     'end': channel_max,
+                    #     'max': channel_max,
+                    #     'min': channel_min,
+                    #     'start': channel_min,
+                    # }
                     if len(self._channelNames) > c:
                         channel_metadata['label'] = self._channelNames[c]
                     if len(self._channelColors) > c:

test/test_sink.py

@@ -1,4 +1,3 @@
-import math
 import subprocess
 from multiprocessing.pool import Pool, ThreadPool
 from os import sys
@@ -419,13 +418,13 @@ def testMetadata(tmp_path):
         assert c.get('family') == 'linear'
         assert not c.get('inverted')
         assert c.get('label') == channel_names[i]
-        window = c.get('window')
-        assert window is not None
-        # max should be nearly 1 and min should be nearly 0
-        assert math.ceil(window.get('end')) == 1
-        assert math.ceil(window.get('max')) == 1
-        assert math.floor(window.get('start')) == 0
-        assert math.floor(window.get('min')) == 0
+        # window = c.get('window')
+        # assert window is not None
+        # # max should be nearly 1 and min should be nearly 0
+        # assert math.ceil(window.get('end')) == 1
+        # assert math.ceil(window.get('max')) == 1
+        # assert math.floor(window.get('start')) == 0
+        # assert math.floor(window.get('min')) == 0
 
     rdefs = omero.get('rdefs')
     assert rdefs is not None