diff --git a/tofu/config.py b/tofu/config.py
index 1a5d4e7..8afb83c 100644
--- a/tofu/config.py
+++ b/tofu/config.py
@@ -34,13 +34,18 @@
     'output-minimum': {
         'default': None,
         'type': float,
-        'help': "Minimum value that maps to zero",
+        'help': "Minimum value that maps to zero (turns on --output-rescale)",
         'metavar': 'MIN'},
     'output-maximum': {
         'default': None,
         'type': float,
-        'help': "Maximum input value that maps to largest output value",
+        'help': "Maximum input value that maps to largest output value (turns on --output-rescale)",
         'metavar': 'MAX'},
+    'output-rescale': {
+        'default': False,
+        'action': 'store_true',
+        'help': "If true rescale grey values either automatically or according to set "
+                "--output-minimum and --output-maximum"},
     'output-bytes-per-file': {
         'default': '128g',
         'type': convert_filesize,
diff --git a/tofu/tasks.py b/tofu/tasks.py
index 5b66468..ffeb9ef 100644
--- a/tofu/tasks.py
+++ b/tofu/tasks.py
@@ -23,16 +23,20 @@ def get_writer(params):
 
     outname = params.output
     LOG.debug("Writing output to {}".format(outname))
-    writer = get_task('write', filename=outname)
+    writer = get_task('write', filename=outname, rescale=params.output_rescale)
 
     writer.props.append = params.output_append
 
     if params.output_bitdepth != 32:
         writer.props.bits = params.output_bitdepth
 
-    if params.output_minimum is not None and params.output_maximum is not None:
+    if params.output_minimum is not None:
         writer.props.minimum = params.output_minimum
+    if params.output_maximum is not None:
         writer.props.maximum = params.output_maximum
+    if params.output_minimum is not None or params.output_maximum is not None:
+        LOG.info('--output-minimum or --output-maximum specified, turning --output-rescale on')
+        writer.props.rescale = True
     if hasattr (writer.props, 'bytes_per_file'):
         writer.props.bytes_per_file = params.output_bytes_per_file
     if hasattr(writer.props, 'tiff_bigtiff'):