Describe color and alpha as planes, not sub-images (#575)
Clarify that color planes refer to the YUV planes, not just the chroma planes.
diff --git a/apps/avifenc.c b/apps/avifenc.c
index 4aa1f90..f499427 100644
--- a/apps/avifenc.c
+++ b/apps/avifenc.c
@@ -104,12 +104,12 @@
printf("\n");
if (avifCodecName(AVIF_CODEC_CHOICE_AOM, 0)) {
printf("aom-specific advanced options:\n");
- printf(" 1. <key>=<value> applies to both the color sub-image and the alpha sub-image (if present).\n");
- printf(" 2. color:<key>=<value> or c:<key>=<value> applies only to the color sub-image.\n");
- printf(" 3. alpha:<key>=<value> or a:<key>=<value> applies only to the alpha sub-image (if present).\n");
- printf(" Since the alpha sub-image is a monochrome image, the options that refer to the chrome planes, such as\n");
- printf(" enable-chroma-deltaq=B, should not be used with the alpha sub-image. In addition, the film grain options\n");
- printf(" are unlikely to make sense for the alpha sub-image.\n");
+ printf(" 1. <key>=<value> applies to both the color (YUV) planes and the alpha plane (if present).\n");
+ printf(" 2. color:<key>=<value> or c:<key>=<value> applies only to the color (YUV) planes.\n");
+ printf(" 3. alpha:<key>=<value> or a:<key>=<value> applies only to the alpha plane (if present).\n");
+ printf(" Since the alpha plane is encoded as a monochrome image, the options that refer to the chroma planes,\n");
+ printf(" such as enable-chroma-deltaq=B, should not be used with the alpha plane. In addition, the film grain\n");
+ printf(" options are unlikely to make sense for the alpha plane.\n");
printf("\n");
printf(" When used with libaom 3.0.0 or later, any key-value pairs supported by the aom_codec_set_option() function\n");
printf(" can be used. When used with libaom 2.0.x or older, the following key-value pairs can be used:\n");
diff --git a/src/codec_aom.c b/src/codec_aom.c
index 7dd26b9..f33869d 100644
--- a/src/codec_aom.c
+++ b/src/codec_aom.c
@@ -402,7 +402,7 @@
{
for (uint32_t i = 0; i < codec->csOptions->count; ++i) {
avifCodecSpecificOption * entry = &codec->csOptions->entries[i];
- // Skip options for the other sub-image.
+ // Skip options for the other kind of plane.
const char * otherPrefix = alpha ? "color:" : "alpha:";
size_t otherPrefixLen = 6;
const char * otherShortPrefix = alpha ? "c:" : "a:";
