From 805dc447076dc580816d730d360de08917d86a9e Mon Sep 17 00:00:00 2001
From: Alexander <homm86@gmail.com>
Date: Fri, 30 Mar 2018 11:29:59 +0300
Subject: [PATCH] improve color cube parser

---
 Tests/test_color_lut.py | 18 +++++++++++-------
 src/PIL/ImageFilter.py  | 15 ++++++++++++---
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/Tests/test_color_lut.py b/Tests/test_color_lut.py
index fffd3341b..4aedd5b43 100644
--- a/Tests/test_color_lut.py
+++ b/Tests/test_color_lut.py
@@ -300,7 +300,6 @@ class TestColorLut3DFilter(PillowTestCase):
     def test_from_cube_file_minimal(self):
         lut = ImageFilter.Color3DLUT.from_cube_file([
             "LUT_3D_SIZE 2",
-            "",
             "0    0 0.031",
             "0.96 0 0.031",
             "0    1 0.031",
@@ -321,6 +320,7 @@ class TestColorLut3DFilter(PillowTestCase):
             'TITLE "LUT name from file"',
             "  LUT_3D_SIZE 2 3 4",
             " SKIP THIS",
+            "",
             " # Comment",
             "CHANNELS 4",
             "",
@@ -343,25 +343,30 @@ class TestColorLut3DFilter(PillowTestCase):
         with self.assertRaisesRegexp(ValueError, "No size found"):
             lut = ImageFilter.Color3DLUT.from_cube_file([
                 'TITLE "LUT name from file"',
-                "",
             ] + [
                 "0    0 0.031",
                 "0.96 0 0.031",
             ] * 3)
 
-        with self.assertRaisesRegexp(ValueError, "number of colors on line 4"):
+        with self.assertRaisesRegexp(ValueError, "number of colors on line 3"):
             lut = ImageFilter.Color3DLUT.from_cube_file([
                 'LUT_3D_SIZE 2',
-                "",
             ] + [
                 "0    0 0.031",
                 "0.96 0 0.031 1",
             ] * 3)
 
-        with self.assertRaisesRegexp(ValueError, "Not a number on line 3"):
+        with self.assertRaisesRegexp(ValueError, "1D LUT cube files"):
+            lut = ImageFilter.Color3DLUT.from_cube_file([
+                'LUT_1D_SIZE 2',
+            ] + [
+                "0    0 0.031",
+                "0.96 0 0.031 1",
+            ])
+
+        with self.assertRaisesRegexp(ValueError, "Not a number on line 2"):
             lut = ImageFilter.Color3DLUT.from_cube_file([
                 'LUT_3D_SIZE 2',
-                "",
             ] + [
                 "0  green 0.031",
                 "0.96 0 0.031",
@@ -371,7 +376,6 @@ class TestColorLut3DFilter(PillowTestCase):
         with NamedTemporaryFile('w+t', delete=False) as f:
             f.write(
                 "LUT_3D_SIZE 2\n"
-                "\n"
                 "0    0 0.031\n"
                 "0.96 0 0.031\n"
                 "0    1 0.031\n"
diff --git a/src/PIL/ImageFilter.py b/src/PIL/ImageFilter.py
index 4fb3db381..8e193798d 100644
--- a/src/PIL/ImageFilter.py
+++ b/src/PIL/ImageFilter.py
@@ -16,6 +16,7 @@
 #
 
 import functools
+from itertools import chain
 
 from ._util import isPath
 
@@ -402,8 +403,6 @@ class Color3DLUT(MultibandFilter):
 
             for i, line in enumerate(iterator, 1):
                 line = line.strip()
-                if not line:
-                    break
                 if line.startswith('TITLE "'):
                     name = line.split('"')[1]
                     continue
@@ -414,12 +413,22 @@ class Color3DLUT(MultibandFilter):
                     continue
                 if line.startswith('CHANNELS '):
                     channels = int(line.split()[1])
+                if line.startswith('LUT_1D_SIZE '):
+                    raise ValueError("1D LUT cube files aren't supported.")
+
+                try:
+                    float(line.partition(' ')[0])
+                except ValueError:
+                    pass
+                else:
+                    # Data starts
+                    break
 
             if size is None:
                 raise ValueError('No size found in the file')
 
             table = []
-            for i, line in enumerate(iterator, i + 1):
+            for i, line in enumerate(chain([line], iterator), i):
                 line = line.strip()
                 if not line or line.startswith('#'):
                     continue