Fix monochrome ICC profile error message in apps (#2673)

Add CHANGELOG entry.

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8faff2c..0350b30 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,7 @@
 
 ### Added since 1.2.0
 
-* Add support for outputting all frames of an image sequence in `avifdec`. 
+* Add support for outputting all frames of an image sequence in `avifdec`.
   `avifdec --index all sequence.avif out.png` creates files named
   `out-xxxxxxxxxx.png` where xxxxxxxxxx are the zero-padded frame indices.
 
@@ -19,6 +19,8 @@
 * Fix local libargparse dependency patch step on macOS 10.15 and earlier.
 * Patch local libyuv dependency for compatibility with gcc 10.
 * Use stricter C99 syntax to avoid related compilation issues.
+* Reject the conversion in avifenc of non-monochrome input to monochrome when an
+  ICC profile is present and not explicitly discarded.
 
 ## [1.2.0] - 2025-02-25
 

apps/shared/avifjpeg.c

diff --git a/apps/shared/avifjpeg.c b/apps/shared/avifjpeg.c
index 09bfb64..88b58cd 100644
--- a/apps/shared/avifjpeg.c
+++ b/apps/shared/avifjpeg.c
@@ -911,7 +911,7 @@
             iccData = iccDataTmp;
             if (requestedFormat == AVIF_PIXEL_FORMAT_YUV400) {
                 fprintf(stderr,
-                        "The image contains an RGB ICC profile which is incompatible with the requested output "
+                        "The image contains a color ICC profile which is incompatible with the requested output "
                         "format YUV400 (grayscale). Pass --ignore-icc to discard the ICC profile.\n");
                 goto cleanup;
             }

apps/shared/avifpng.c

diff --git a/apps/shared/avifpng.c b/apps/shared/avifpng.c
index 9727ea9..6abd16b 100644
--- a/apps/shared/avifpng.c
+++ b/apps/shared/avifpng.c
@@ -368,7 +368,7 @@
             if (rawColorType != PNG_COLOR_TYPE_GRAY && rawColorType != PNG_COLOR_TYPE_GRAY_ALPHA &&
                 avif->yuvFormat == AVIF_PIXEL_FORMAT_YUV400) {
                 fprintf(stderr,
-                        "The image contains an RGB ICC profile which is incompatible with the requested output "
+                        "The image contains a color ICC profile which is incompatible with the requested output "
                         "format YUV400 (grayscale). Pass --ignore-icc to discard the ICC profile.\n");
                 goto cleanup;
             }