Refactoring, because it was bugging me.

lib/galaxy/datatypes/images.py

@@ -8,8 +8,8 @@ from six.moves.urllib.parse import quote_plus
 from galaxy.datatypes.binary import Binary
 from galaxy.datatypes.sniff import get_headers
 from galaxy.datatypes.text import Html as HtmlFromText
-from galaxy.datatypes.util.image_util import check_image_type
 from galaxy.util import nice_size
+from galaxy.util.image_util import check_image_type
 from . import data
 
 log = logging.getLogger(__name__)

lib/galaxy/datatypes/sequence.py

@@ -15,9 +15,9 @@ from six import PY3
 from galaxy import util
 from galaxy.datatypes import metadata
 from galaxy.util.checkers import is_gzip
+from galaxy.util.image_util import check_image_type
 from galaxy.datatypes.metadata import MetadataElement
 from galaxy.datatypes.sniff import get_headers
-from galaxy.datatypes.util.image_util import check_image_type
 from galaxy.util import nice_size
 from . import data
 

lib/galaxy/util/checkers.py

@@ -1,22 +1,16 @@
 import bz2
 import gzip
-import imghdr
 import re
 import zipfile
 
 from six import StringIO
 
 from galaxy import util
+from galaxy.util.image_util import image_type
 
 HTML_CHECK_LINES = 100
 
 
-def check_image( file_path ):
-    if imghdr.what( file_path ) is not None:
-        return True
-    return False
-
-
 def check_html( file_path, chunk=None ):
     if chunk is None:
         temp = open( file_path, "U" )
@@ -126,6 +120,13 @@ def is_gzip( file_path ):
     return is_gzipped
 
 
+def check_image( file_path ):
+    """ Simple wrapper around image_type to yield a True/False verdict """
+    if image_type( file_path ):
+        return True
+    return False
+
+
 __all__ = [
     'check_binary',
     'check_bz2',

tools/data_source/upload.py

@@ -20,17 +20,10 @@ from galaxy import util
 from galaxy.datatypes import sniff
 from galaxy.datatypes.binary import Binary
 from galaxy.datatypes.registry import Registry
-from galaxy.datatypes.util.image_util import get_image_ext
 from galaxy.util import multi_byte
-from galaxy.util.checkers import check_binary, check_bz2, check_gzip, check_html, check_image, check_zip
+from galaxy.util.checkers import check_binary, check_bz2, check_gzip, check_html, check_zip
+from galaxy.util.image_util import get_image_ext
 
-try:
-    import Image as PIL
-except ImportError:
-    try:
-        from PIL import Image as PIL
-    except:
-        PIL = None
 
 try:
     import bz2
@@ -116,8 +109,9 @@ def add_file( dataset, registry, json_file, output_path ):
         except UnicodeDecodeError as e:
             dataset.is_multi_byte = False
     # Is dataset an image?
-    if check_image( dataset.path ):
-        ext = get_image_ext( dataset.path )
+    i_ext = get_image_ext( dataset.path )
+    if i_ext:
+        ext = i_ext
         data_type = ext
     # Is dataset content multi-byte?
     elif dataset.is_multi_byte: