Remove AVIF_ENABLE_GAIN_MAP flag.

.github/workflows/ci-fuzztest.yml

@@ -50,7 +50,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_FUZZTEST=ON

.github/workflows/ci-linux-golden-tests.yml

@@ -46,7 +46,6 @@ jobs:
           -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF
           -DAVIF_CODEC_AOM=LOCAL -DAVIF_LIBYUV=LOCAL
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_LIBXML2=LOCAL
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GOLDEN_TESTS=ON
           -DAVIF_ENABLE_GTEST=OFF -DAVIF_ENABLE_WERROR=ON

.github/workflows/ci-linux-static-old-local.yml

@@ -51,7 +51,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_LOCAL_GTEST=ON
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_WERROR=ON
       - name: Build libavif (ninja)

.github/workflows/ci-unix-shared-local.yml

@@ -55,7 +55,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_WERROR=ON

.github/workflows/ci-unix-static.yml

@@ -59,7 +59,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_WERROR=ON

.github/workflows/ci-windows-installed.yml

@@ -74,7 +74,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_WERROR=ON $env:AVIF_CMAKE_C_COMPILER $env:AVIF_CMAKE_CXX_COMPILER

.github/workflows/ci-windows-shared-local.yml

@@ -54,7 +54,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_WERROR=ON $env:AVIF_CMAKE_C_COMPILER $env:AVIF_CMAKE_CXX_COMPILER

.github/workflows/ci-windows.yml

@@ -67,7 +67,6 @@ jobs:
           -DAVIF_BUILD_EXAMPLES=ON -DAVIF_BUILD_APPS=ON
           -DAVIF_BUILD_TESTS=ON -DAVIF_ENABLE_GTEST=ON -DAVIF_GTEST=LOCAL
           -DAVIF_ENABLE_EXPERIMENTAL_YCGCO_R=ON
-          -DAVIF_ENABLE_GAIN_MAP=ON
           -DAVIF_ENABLE_EXPERIMENTAL_MINI=ON
           -DAVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM=ON
           -DAVIF_ENABLE_WERROR=ON

CMakeLists.txt

@@ -64,10 +64,6 @@ option(BUILD_SHARED_LIBS "Build shared avif library" ON)
 
 option(AVIF_ENABLE_WERROR "Treat all compiler warnings as errors" OFF)
 
-option(AVIF_ENABLE_GAIN_MAP
-       "Enable gain map code (for HDR images that look good both on HDR and SDR displays)" ON
-)
-
 option(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R "Enable experimental YCgCo-R matrix code" OFF)
 option(AVIF_ENABLE_EXPERIMENTAL_MINI "Enable experimental reduced header" OFF)
 option(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM "Enable experimental sample transform code" OFF)
@@ -273,13 +269,10 @@ if(AVIF_LIBSHARPYUV_ENABLED)
 endif(AVIF_LIBSHARPYUV_ENABLED)
 
 set_local_or_system_option(
-    "LIBXML2" "OFF" "Use libxml2. When enabled and AVIF_ENABLE_GAIN_MAP is ON, \
-    allows converting JPEG files with gain maps to AVIF using avifenc"
+    "LIBXML2" "OFF" "Use libxml2. When enabled, allows converting jpeg files with gain maps to avif using avifenc"
 )
+check_avif_option(AVIF_LIBXML2 TARGET LibXml2::LibXml2 PKG_NAME LibXml2)
 
-if(AVIF_ENABLE_GAIN_MAP)
-    check_avif_option(AVIF_LIBXML2 TARGET LibXml2::LibXml2 PKG_NAME LibXml2)
-endif()
 # ---------------------------------------------------------------------------------------
 
 # Enable all warnings
@@ -365,10 +358,6 @@ if(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
     add_compile_definitions(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R)
 endif()
 
-if(AVIF_ENABLE_GAIN_MAP)
-    add_compile_definitions(AVIF_ENABLE_GAIN_MAP)
-endif()
-
 if(AVIF_ENABLE_EXPERIMENTAL_MINI)
     add_compile_definitions(AVIF_ENABLE_EXPERIMENTAL_MINI)
 endif()
@@ -384,6 +373,7 @@ set(AVIF_SRCS
     src/colrconvert.c
     src/diag.c
     src/exif.c
+    src/gainmap.c
     src/io.c
     src/mem.c
     src/obu.c
@@ -397,9 +387,6 @@ set(AVIF_SRCS
     src/utils.c
     src/write.c
 )
-if(AVIF_ENABLE_GAIN_MAP)
-    list(APPEND AVIF_SRCS src/gainmap.c)
-endif()
 if(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM)
     list(APPEND AVIF_SRCS src/sampletransform.c)
 endif()
@@ -585,7 +572,7 @@ if(NOT AVIF_CODEC_AOM_ENABLED
     message(WARNING "libavif: No decoding library is enabled.")
 endif()
 
-if(AVIF_LIB_USE_CXX OR (AVIF_BUILD_APPS AND AVIF_ENABLE_GAIN_MAP) OR (AVIF_BUILD_TESTS AND (AVIF_ENABLE_FUZZTEST
+if(AVIF_LIB_USE_CXX OR AVIF_BUILD_APPS OR (AVIF_BUILD_TESTS AND (AVIF_ENABLE_FUZZTEST
                                                                                                          OR AVIF_ENABLE_GTEST))
 )
     enable_language(CXX)
@@ -677,13 +664,11 @@ if(AVIF_BUILD_APPS OR (AVIF_BUILD_TESTS AND (AVIF_ENABLE_FUZZTEST OR AVIF_ENABLE
         find_package(JPEG REQUIRED)
     endif()
 
-    if(AVIF_ENABLE_GAIN_MAP)
-        if(TARGET LibXml2::LibXml2)
-            set(AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION TRUE)
-            add_compile_definitions(AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION)
-        else()
-            message(STATUS "libavif: libxml2 not found; avifenc will ignore any gain map in jpeg files")
-        endif()
+    if(TARGET LibXml2::LibXml2)
+        set(AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION TRUE)
+        add_compile_definitions(AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION)
+    else()
+        message(STATUS "libavif: libxml2 not found; avifenc will ignore any gain map in jpeg files")
     endif()
 
     set(AVIF_APPS_SRCS apps/shared/avifexif.c apps/shared/avifjpeg.c apps/shared/avifpng.c apps/shared/avifutil.c
@@ -755,33 +740,32 @@ if(AVIF_BUILD_APPS)
             LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
         )
     endif()
-    if(AVIF_ENABLE_GAIN_MAP)
-        include(LocalLibargparse)
-        set(AVIFGAINMAPUTIL_SRCS
-            apps/avifgainmaputil/avifgainmaputil.cc
-            apps/avifgainmaputil/convert_command.cc
-            apps/avifgainmaputil/combine_command.cc
-            apps/avifgainmaputil/extractgainmap_command.cc
-            apps/avifgainmaputil/imageio.cc
-            apps/avifgainmaputil/printmetadata_command.cc
-            apps/avifgainmaputil/tonemap_command.cc
-            apps/avifgainmaputil/program_command.cc
-            apps/avifgainmaputil/swapbase_command.cc
-        )
+    include(LocalLibargparse)
+
+    set(AVIFGAINMAPUTIL_SRCS
+        apps/avifgainmaputil/avifgainmaputil.cc
+        apps/avifgainmaputil/convert_command.cc
+        apps/avifgainmaputil/combine_command.cc
+        apps/avifgainmaputil/extractgainmap_command.cc
+        apps/avifgainmaputil/imageio.cc
+        apps/avifgainmaputil/printmetadata_command.cc
+        apps/avifgainmaputil/tonemap_command.cc
+        apps/avifgainmaputil/program_command.cc
+        apps/avifgainmaputil/swapbase_command.cc
+    )
 
-        add_executable(avifgainmaputil "${AVIFGAINMAPUTIL_SRCS}")
-        if(WIN32)
-            if(MSVC)
-                target_sources(avifgainmaputil PRIVATE apps/utf8.manifest)
-            elseif(MINGW)
-                target_sources(avifgainmaputil PRIVATE apps/utf8.rc)
-            endif()
+    add_executable(avifgainmaputil "${AVIFGAINMAPUTIL_SRCS}")
+    if(WIN32)
+        if(MSVC)
+            target_sources(avifgainmaputil PRIVATE apps/utf8.manifest)
+        elseif(MINGW)
+            target_sources(avifgainmaputil PRIVATE apps/utf8.rc)
         endif()
-        set_target_properties(avifgainmaputil PROPERTIES LINKER_LANGUAGE "CXX")
-        target_include_directories(avifgainmaputil PRIVATE apps/avifgainmaputil/)
-        target_link_libraries(avifgainmaputil libargparse avif_apps avif avif_enable_warnings)
-        # Don't add avifgainmaputil to installed apps for now.
     endif()
+    set_target_properties(avifgainmaputil PROPERTIES LINKER_LANGUAGE "CXX")
+    target_include_directories(avifgainmaputil PRIVATE apps/avifgainmaputil/)
+    target_link_libraries(avifgainmaputil libargparse avif_apps avif avif_enable_warnings)
+    # Don't add avifgainmaputil to installed apps for now.
 endif()
 
 if(AVIF_BUILD_TESTS)

apps/avifenc.c

@@ -57,8 +57,7 @@ typedef struct
     avifBool ignoreXMP;
     avifBool ignoreColorProfile;
 
-    // These settings are only relevant when compiled with AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION
-    // (which also implies AVIF_ENABLE_GAIN_MAP).
+    // These settings are only relevant when compiled with AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION.
     avifBool qualityGainMapIsConstrained; // true if qualityGainMap explicitly set by the user
     int qualityGainMap;
     avifBool ignoreGainMap; // ignore any gain map present in the input file.

apps/shared/avifjpeg.h

@@ -15,8 +15,7 @@ extern "C" {
 // bytes of Exif or XMP metadata will be read or an error returned.
 // 'ignoreGainMap' is only relevant for jpeg files that have a gain map
 // and only if AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION is ON
-// (requires AVIF_ENABLE_GAIN_MAP and libxml2). Otherwise
-// it has no effect.
+// (requires libxml2). Otherwise it has no effect.
 avifBool avifJPEGRead(const char * inputFilename,
                       avifImage * avif,
                       avifPixelFormat requestedFormat,

apps/shared/avifutil.c

@@ -125,7 +125,6 @@ static void avifImageDumpInternal(const avifImage * avif, uint32_t gridCols, uin
         printf(" * CLLI           : %hu, %hu\n", avif->clli.maxCLL, avif->clli.maxPALL);
     }
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
     printf(" * Gain map       : ");
     avifImage * gainMapImage = avif->gainMap ? avif->gainMap->image : NULL;
     if (gainMapImage != NULL) {
@@ -161,7 +160,6 @@ static void avifImageDumpInternal(const avifImage * avif, uint32_t gridCols, uin
     } else {
         printf("Absent\n");
     }
-#endif // AVIF_ENABLE_GAIN_MAP
 }
 
 void avifImageDump(const avifImage * avif, uint32_t gridCols, uint32_t gridRows, avifProgressiveState progressiveState)

apps/shared/avifutil.h

@@ -67,8 +67,7 @@ struct y4mFrameIterator;
 // Returns AVIF_APP_FILE_FORMAT_UNKNOWN in case of error.
 // 'ignoreGainMap' is only relevant for jpeg files that have a gain map
 // and only if AVIF_ENABLE_EXPERIMENTAL_JPEG_GAIN_MAP_CONVERSION is ON
-// (requires AVIF_ENABLE_GAIN_MAP and libxml2). Otherwise
-// it has no effect.
+// (requires libxml2). Otherwise it has no effect.
 avifAppFileFormat avifReadImage(const char * filename,
                                 avifPixelFormat requestedFormat,
                                 int requestedDepth,

include/avif/avif.h

@@ -193,11 +193,9 @@ typedef enum AVIF_NODISCARD avifResult
     AVIF_RESULT_CANNOT_CHANGE_SETTING = 27, // a setting that can't change is changed during encoding
     AVIF_RESULT_INCOMPATIBLE_IMAGE = 28,    // the image is incompatible with already encoded images
     AVIF_RESULT_INTERNAL_ERROR = 29,        // some invariants have not been satisfied (likely a bug in libavif)
-#if defined(AVIF_ENABLE_GAIN_MAP)
     AVIF_RESULT_ENCODE_GAIN_MAP_FAILED = 30,
     AVIF_RESULT_DECODE_GAIN_MAP_FAILED = 31,
     AVIF_RESULT_INVALID_TONE_MAPPED_IMAGE = 32,
-#endif
 #if defined(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM)
     AVIF_RESULT_ENCODE_SAMPLE_TRANSFORM_FAILED = 33,
     AVIF_RESULT_DECODE_SAMPLE_TRANSFORM_FAILED = 34,
@@ -590,7 +588,6 @@ typedef struct avifContentLightLevelInformationBox
     uint16_t maxPALL;
 } avifContentLightLevelInformationBox;
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
 // ---------------------------------------------------------------------------
 // avifGainMap
 // Gain Maps are a solution for a consistent and adaptive display of HDR images.
@@ -700,8 +697,6 @@ AVIF_API avifGainMap * avifGainMapCreate(void);
 // Frees a gain map, including the 'image' field if non NULL.
 AVIF_API void avifGainMapDestroy(avifGainMap * gainMap);
 
-#endif // AVIF_ENABLE_GAIN_MAP
-
 // ---------------------------------------------------------------------------
 
 #if defined(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM)
@@ -828,22 +823,19 @@ typedef struct avifImage
     avifImageItemProperty * properties; // NULL only if numProperties is 0.
     size_t numProperties;
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
     // Gain map image and metadata. NULL if no gain map is present.
     // Owned by the avifImage and gets freed when calling avifImageDestroy().
     // gainMap->image->transformFlags is always AVIF_TRANSFORM_NONE.
     avifGainMap * gainMap;
-#endif
 } avifImage;
 
 // avifImageCreate() and avifImageCreateEmpty() return NULL if arguments are invalid or if a memory allocation failed.
 AVIF_NODISCARD AVIF_API avifImage * avifImageCreate(uint32_t width, uint32_t height, uint32_t depth, avifPixelFormat yuvFormat);
 AVIF_NODISCARD AVIF_API avifImage * avifImageCreateEmpty(void); // helper for making an image to decode into
-// Performs a deep copy of an image, including all metadata and planes, and the gain map metadata/planes if present
-// and if AVIF_ENABLE_GAIN_MAP is defined.
+// Performs a deep copy of an image, including all metadata and planes, and the gain map metadata/planes if present.
 AVIF_API avifResult avifImageCopy(avifImage * dstImage, const avifImage * srcImage, avifPlanesFlags planes);
 // Performs a shallow copy of a rectangular area of an image. 'dstImage' does not own the planes.
-// Ignores the gainMap field (which exists only if AVIF_ENABLE_GAIN_MAP is defined).
+// Ignores the gainMap field.
 AVIF_API avifResult avifImageSetViewRect(avifImage * dstImage, const avifImage * srcImage, const avifCropRect * rect);
 AVIF_API void avifImageDestroy(avifImage * image);
 
@@ -856,8 +848,7 @@ AVIF_API avifResult avifImageSetMetadataExif(avifImage * image, const uint8_t *
 // Sets XMP metadata.
 AVIF_API avifResult avifImageSetMetadataXMP(avifImage * image, const uint8_t * xmp, size_t xmpSize);
 
-// Allocate/free/steal planes. These functions ignore the gainMap field (which exists only if
-// AVIF_ENABLE_GAIN_MAP is defined).
+// Allocate/free/steal planes. These functions ignore the gainMap field.
 AVIF_API avifResult avifImageAllocatePlanes(avifImage * image, avifPlanesFlags planes); // Ignores any pre-existing planes
 AVIF_API void avifImageFreePlanes(avifImage * image, avifPlanesFlags planes);           // Ignores already-freed planes
 AVIF_API void avifImageStealPlanes(avifImage * dstImage, avifImage * srcImage, avifPlanesFlags planes);
@@ -1199,12 +1190,8 @@ typedef enum avifImageContentTypeFlag
     AVIF_IMAGE_CONTENT_NONE = 0,
     // Color only or alpha only is not currently supported.
     AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA = (1 << 0) | (1 << 1),
-#if defined(AVIF_ENABLE_GAIN_MAP)
     AVIF_IMAGE_CONTENT_GAIN_MAP = (1 << 2),
     AVIF_IMAGE_CONTENT_ALL = AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA | AVIF_IMAGE_CONTENT_GAIN_MAP,
-#else
-    AVIF_IMAGE_CONTENT_ALL = AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA,
-#endif
 
     AVIF_IMAGE_CONTENT_DECODE_DEFAULT = AVIF_IMAGE_CONTENT_COLOR_AND_ALPHA,
 } avifImageContentTypeFlag;
@@ -1394,10 +1381,10 @@ AVIF_API avifResult avifDecoderNthImageTiming(const avifDecoder * decoder, uint3
 // function can be called next to retrieve the number of top rows that can be immediately accessed
 // from the luma plane of decoder->image, and alpha if any. The corresponding rows from the chroma planes,
 // if any, can also be accessed (half rounded up if subsampled, same number of rows otherwise).
-// If a gain map is present and AVIF_ENABLE_GAIN_MAP is on and
-// (imageContentToDecode & AVIF_IMAGE_CONTENT_GAIN_MAP) is nonzero, the gain map's planes can also be accessed
-// in the same way. If the gain map's height is different from the main image, then the number of
-// available gain map rows is at least:
+// If a gain map is present and  (imageContentToDecode & AVIF_IMAGE_CONTENT_GAIN_MAP) is nonzero,
+// the gain map's planes can also be accessed in the same way.
+// If the gain map's height is different from the main image, then the number of available gain map
+// rows is at least:
 // roundf((float)decoded_row_count / decoder->image->height * decoder->image->gainMap.image->height)
 // When gain map scaling is needed, callers might choose to use a few less rows depending on how many rows
 // are needed by the scaling algorithm, to avoid the last row(s) changing when more data becomes available.
@@ -1517,9 +1504,7 @@ typedef struct avifEncoder
 
     // Version 1.1.0 ends here. Add any new members after this line.
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
     int qualityGainMap; // changeable encoder setting
-#endif
 
 #if defined(AVIF_ENABLE_EXPERIMENTAL_SAMPLE_TRANSFORM)
     // Perform extra steps at encoding and decoding to extend AV1 features using bundled additional image items.
@@ -1587,10 +1572,8 @@ AVIF_API avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output
 // AVIF_RESULT_INVALID_CODEC_SPECIFIC_OPTION from avifEncoderWrite() or avifEncoderAddImage().
 AVIF_API avifResult avifEncoderSetCodecSpecificOption(avifEncoder * encoder, const char * key, const char * value);
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
 // Returns the size in bytes of the AV1 image item containing gain map samples, or 0 if no gain map was encoded.
 AVIF_API size_t avifEncoderGetGainMapSizeBytes(avifEncoder * encoder);
-#endif
 
 // Helpers
 AVIF_NODISCARD AVIF_API avifBool avifImageUsesU16(const avifImage * image);
@@ -1605,7 +1588,6 @@ AVIF_API uint32_t avifImagePlaneHeight(const avifImage * image, int channel);
 // either the brand 'avif' or 'avis' (or both), without performing any allocations.
 AVIF_NODISCARD AVIF_API avifBool avifPeekCompatibleFileType(const avifROData * input);
 
-#if defined(AVIF_ENABLE_GAIN_MAP)
 // ---------------------------------------------------------------------------
 // Gain Map utilities.
 // Gain Maps are a HIGHLY EXPERIMENTAL FEATURE, see comments in the avifGainMap
@@ -1658,8 +1640,6 @@ AVIF_API avifResult avifImageComputeGainMap(const avifImage * baseImage,
                                             avifGainMap * gainMap,
                                             avifDiagnostics * diag);
 
-#endif // AVIF_ENABLE_GAIN_MAP
-
 #ifdef __cplusplus
 } // extern "C"
 #endif