Renamed IsImageGray to SetImageGray and IsImageMonochrome to SetImageMonochrome since they change the type of the image.
Added new IsImageGray and IsImageMonochrome that only check if the image is gray or monochrome.
diff --git a/coders/dib.c b/coders/dib.c
index 5ab95f3..b324f20 100644
--- a/coders/dib.c
+++ b/coders/dib.c
@@ -1059,7 +1059,7 @@
dib_info.bits_per_pixel=8;
if (image_info->depth > 8)
dib_info.bits_per_pixel=16;
- if (IsImageMonochrome(image,exception) != MagickFalse)
+ if (SetImageMonochrome(image,exception) != MagickFalse)
dib_info.bits_per_pixel=1;
dib_info.number_colors=(dib_info.bits_per_pixel == 16) ? 0 :
(1UL << dib_info.bits_per_pixel);