gif2webp: add -sharp_yuv/-near_lossless

This change is the same as the one that introduced the options to
img2webp:
0825faa img2webp: add -sharp_yuv/-near_lossless

Change-Id: Id380d159299c38dd6440f833d487e00c0976afec

CMakeLists.txt

@@ -567,7 +567,8 @@ if(WEBP_BUILD_GIF2WEBP)
   add_executable(gif2webp ${GIF2WEBP_SRCS})
   target_link_libraries(gif2webp exampleutil imageioutil webp libwebpmux
                         ${WEBP_DEP_GIF_LIBRARIES})
-  target_include_directories(gif2webp PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src)
+  target_include_directories(gif2webp PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src
+                                              ${CMAKE_CURRENT_SOURCE_DIR})
   install(TARGETS gif2webp RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 endif()
 

doc/tools.md

@@ -354,6 +354,10 @@ Options:
 -lossy ................. encode image using lossy compression
 -mixed ................. for each frame in the image, pick lossy
                          or lossless compression heuristically
+-near_lossless <int> ... use near-lossless image preprocessing
+                         (0..100=off), default=100
+-sharp_yuv ............. use sharper (and slower) RGB->YUV conversion
+                         (lossy only)
 -q <float> ............. quality factor (0:small..100:big)
 -m <int> ............... compression method (0=fast, 6=slowest)
 -min_size .............. minimize output size (default:off)

examples/Makefile.am

@@ -67,7 +67,7 @@ dwebp_LDADD += ../src/libwebp.la
 dwebp_LDADD +=$(PNG_LIBS) $(JPEG_LIBS)
 
 gif2webp_SOURCES = gif2webp.c gifdec.c gifdec.h
-gif2webp_CPPFLAGS = $(AM_CPPFLAGS) $(GIF_INCLUDES)
+gif2webp_CPPFLAGS = $(AM_CPPFLAGS) $(GIF_INCLUDES) -I$(top_srcdir)
 gif2webp_LDADD  =
 gif2webp_LDADD += libexample_util.la
 gif2webp_LDADD += ../imageio/libimageio_util.la

examples/gif2webp.c

@@ -28,6 +28,7 @@
 #endif
 
 #include <gif_lib.h>
+#include "sharpyuv/sharpyuv.h"
 #include "webp/encode.h"
 #include "webp/mux.h"
 #include "../examples/example_util.h"
@@ -70,6 +71,11 @@ static void Help(void) {
   printf("  -lossy ................. encode image using lossy compression\n");
   printf("  -mixed ................. for each frame in the image, pick lossy\n"
          "                           or lossless compression heuristically\n");
+  printf("  -near_lossless <int> ... use near-lossless image preprocessing\n"
+         "                           (0..100=off), default=100\n");
+  printf("  -sharp_yuv ............. use sharper (and slower) RGB->YUV "
+                                    "conversion\n"
+         "                           (lossy only)\n");
   printf("  -q <float> ............. quality factor (0:small..100:big)\n");
   printf("  -m <int> ............... compression method (0=fast, 6=slowest)\n");
   printf("  -min_size .............. minimize output size (default:off)\n"
@@ -166,6 +172,10 @@ int main(int argc, const char* argv[]) {
     } else if (!strcmp(argv[c], "-mixed")) {
       enc_options.allow_mixed = 1;
       config.lossless = 0;
+    } else if (!strcmp(argv[c], "-near_lossless") && c < argc - 1) {
+      config.near_lossless = ExUtilGetInt(argv[++c], 0, &parse_error);
+    } else if (!strcmp(argv[c], "-sharp_yuv")) {
+      config.use_sharp_yuv = 1;
     } else if (!strcmp(argv[c], "-loop_compatibility")) {
       loop_compatibility = 1;
     } else if (!strcmp(argv[c], "-q") && c < argc - 1) {
@@ -226,10 +236,13 @@ int main(int argc, const char* argv[]) {
     } else if (!strcmp(argv[c], "-version")) {
       const int enc_version = WebPGetEncoderVersion();
       const int mux_version = WebPGetMuxVersion();
+      const int sharpyuv_version = SharpYuvGetVersion();
       printf("WebP Encoder version: %d.%d.%d\nWebP Mux version: %d.%d.%d\n",
              (enc_version >> 16) & 0xff, (enc_version >> 8) & 0xff,
              enc_version & 0xff, (mux_version >> 16) & 0xff,
              (mux_version >> 8) & 0xff, mux_version & 0xff);
+      printf("libsharpyuv: %d.%d.%d\n", (sharpyuv_version >> 24) & 0xff,
+             (sharpyuv_version >> 16) & 0xffff, sharpyuv_version & 0xff);
       FREE_WARGV_AND_RETURN(EXIT_SUCCESS);
     } else if (!strcmp(argv[c], "-quiet")) {
       quiet = 1;

man/gif2webp.1

@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH GIF2WEBP 1 "July 18, 2024"
+.TH GIF2WEBP 1 "November 4, 2024"
 .SH NAME
 gif2webp \- Convert a GIF image to WebP
 .SH SYNOPSIS
@@ -39,6 +39,18 @@ Encode the image using lossy compression.
 Mixed compression mode: optimize compression of the image by picking either
 lossy or lossless compression for each frame heuristically.
 .TP
+.BI \-near_lossless " int
+Specify the level of near\-lossless image preprocessing. This option adjusts
+pixel values to help compressibility, but has minimal impact on the visual
+quality. It triggers lossless compression mode automatically. The range is 0
+(maximum preprocessing) to 100 (no preprocessing, the default). The typical
+value is around 60. Note that lossy with \fB\-q 100\fP can at times yield
+better results.
+.TP
+.B \-sharp_yuv
+Use more accurate and sharper RGB->YUV conversion. Note that this process is
+slower than the default 'fast' RGB->YUV conversion.
+.TP
 .BI \-q " float
 Specify the compression factor for RGB channels between 0 and 100. The default
 is 75.