From a2535ce6300a6190cfb2e63b088d4e8d7b699826 Mon Sep 17 00:00:00 2001
From: Stephen Seo <seo.disparate@gmail.com>
Date: Sat, 27 Nov 2021 13:17:35 +0900
Subject: [PATCH] Add check: color-dithering usage on colored Image

---
 src/image.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/image.cc b/src/image.cc
index 73ae9fe..5ebffc1 100644
--- a/src/image.cc
+++ b/src/image.cc
@@ -883,6 +883,13 @@ std::unique_ptr<Image> Image::ToColorDitheredWithBlueNoise(Image *blue_noise) {
     return {};
   }
 
+  if (this->IsGrayscale()) {
+    std::cout << "ERROR ToColorDitheredWithBlueNoise: current Image is not "
+                 "non-grayscale"
+              << std::endl;
+    return {};
+  }
+
   auto opencl_handle = GetOpenCLHandle();
   if (!opencl_handle) {
     std::cout