Reduce memory allocation during some styling operations

Specifically, when we apply a style, in some instances the tile or
region is converted from one dtype to a float in order to preserve some
of the transform properties through the process.  We had been using
`float`, which internally is `np.float64`.  But, `np.float32` gives
sufficient accuracy for our styles.  With this change, `np.float32` is
used unless the base datatype is `float64`, in which we do not reduce
the precision.

CHANGELOG.md

@@ -10,6 +10,7 @@
 - Add an endpoint to make it easier to replace thumbnails ([#1253](../../pull/1253))
 - Presets from Large Image Configuration file ([#1248](../../pull/1248), [#1256](../../pull/1256))
 - Reduce memory allocation during some region tiling operations ([#1261](../../pull/1261))
+- Reduce memory allocation during some styling operations ([#1262](../../pull/1262))
 
 ### Changes
 - Minor code changes based on suggestions from ruff linting ([#1257](../../pull/1257))

large_image/tilesource/base.py

@@ -1420,7 +1420,9 @@ def _applyStyle(self, image, style, x, y, z, frame=None):  # noqa
         if not style or ('icc' in style and len(style) == 1):
             sc.output = image
         else:
-            sc.output = np.zeros((image.shape[0], image.shape[1], 4), float)
+            sc.output = np.zeros(
+                (image.shape[0], image.shape[1], 4),
+                np.float32 if image.dtype != np.float64 else image.dtype)
         image = self._applyStyleFunction(image, sc, 'pre')
         for eidx, entry in enumerate(sc.style['bands']):
             sc.styleIndex = eidx