make autosubsample more consistent

jcupitt · jcupitt · commit 595f5a1b71d0 · 2021-03-27T15:16:38.000Z
always disable subsample for Q&gt;=90, and update docs too
diff --git a/libvips/foreign/heifsave.c b/libvips/foreign/heifsave.c
@@ -370,7 +370,7 @@ vips_foreign_save_heif_build( VipsObject *object )
 
 	chroma = heif->subsample_mode == VIPS_FOREIGN_SUBSAMPLE_OFF ||
 		( heif->subsample_mode == VIPS_FOREIGN_SUBSAMPLE_AUTO &&
-			heif->Q > 90 ) ? "444" : "420";
+			heif->Q >= 90 ) ? "444" : "420";
 	error = heif_encoder_set_parameter_string( heif->encoder,
 		"chroma", chroma );
 	if( error.code &&
@@ -727,7 +727,7 @@ vips_foreign_save_heif_target_init( VipsForeignSaveHeifTarget *target )
  * Use @speed to control the CPU effort spent improving compression.
  * This is currently only applicable to AV1 encoders, defaults to 5.
  *
- * Chroma subsampling is normally automatically disabled for Q > 90. You can
+ * Chroma subsampling is normally automatically disabled for Q >= 90. You can
  * force the subsampling mode with @subsample_mode.
  *
  * See also: vips_image_write_to_file(), vips_heifload().
diff --git a/libvips/foreign/jp2ksave.c b/libvips/foreign/jp2ksave.c
@@ -1076,7 +1076,7 @@ vips_foreign_save_jp2k_target_init( VipsForeignSaveJp2kTarget *target )
  *
  * Use @tile_width and @tile_height to set the tile size. The default is 512.
  *
- * Chroma subsampling is normally automatically disabled for Q > 90. You can
+ * Chroma subsampling is normally automatically disabled for Q >= 90. You can
  * force the subsampling mode with @subsample_mode.
  *
  * This operation always writes a pyramid.
diff --git a/libvips/foreign/jpegsave.c b/libvips/foreign/jpegsave.c
@@ -557,7 +557,7 @@ vips_foreign_save_jpeg_mime_init( VipsForeignSaveJpegMime *mime )
  * If @strip is set, no EXIF data, IPTC data, ICC profile or XMP metadata is 
  * written into the output file.
  *
- * Chroma subsampling is normally automatically disabled for Q > 90. You can
+ * Chroma subsampling is normally automatically disabled for Q >= 90. You can
  * force the subsampling mode with @subsample_mode.
  *
  * If @trellis_quant is set and the version of libjpeg supports it
diff --git a/libvips/include/vips/foreign.h b/libvips/include/vips/foreign.h
@@ -372,7 +372,7 @@ int vips_openslideload_source( VipsSource *source, VipsImage **out, ... )
 
 /**
  * VipsForeignSubsample:
- * @VIPS_FOREIGN_SUBSAMPLE_AUTO: prevent subsampling when quality > 90
+ * @VIPS_FOREIGN_SUBSAMPLE_AUTO: prevent subsampling when quality >= 90
  * @VIPS_FOREIGN_SUBSAMPLE_ON: always perform subsampling
  * @VIPS_FOREIGN_SUBSAMPLE_OFF: never perform subsampling
  *

Original file line number	Diff line number	Diff line change
`@@ -1076,7 +1076,7 @@ vips_foreign_save_jp2k_target_init( VipsForeignSaveJp2kTarget *target )`
`1076`	`1076`	`*`
`1077`	`1077`	`* Use @tile_width and @tile_height to set the tile size. The default is 512.`
`1078`	`1078`	`*`
`1079`		`- * Chroma subsampling is normally automatically disabled for Q > 90. You can`
	`1079`	`+ * Chroma subsampling is normally automatically disabled for Q >= 90. You can`
`1080`	`1080`	`* force the subsampling mode with @subsample_mode.`
`1081`	`1081`	`*`
`1082`	`1082`	`* This operation always writes a pyramid.`
Original file line number	Diff line number	Diff line change
`@@ -557,7 +557,7 @@ vips_foreign_save_jpeg_mime_init( VipsForeignSaveJpegMime *mime )`
`557`	`557`	`* If @strip is set, no EXIF data, IPTC data, ICC profile or XMP metadata is`
`558`	`558`	`* written into the output file.`
`559`	`559`	`*`
`560`		`- * Chroma subsampling is normally automatically disabled for Q > 90. You can`
	`560`	`+ * Chroma subsampling is normally automatically disabled for Q >= 90. You can`
`561`	`561`	`* force the subsampling mode with @subsample_mode.`
`562`	`562`	`*`
`563`	`563`	`* If @trellis_quant is set and the version of libjpeg supports it`
Original file line number	Diff line number	Diff line change
`@@ -372,7 +372,7 @@ int vips_openslideload_source( VipsSource source, VipsImage *out, ... )`
`372`	`372`
`373`	`373`	`/**`
`374`	`374`	`* VipsForeignSubsample:`
`375`		`- * @VIPS_FOREIGN_SUBSAMPLE_AUTO: prevent subsampling when quality > 90`
	`375`	`+ * @VIPS_FOREIGN_SUBSAMPLE_AUTO: prevent subsampling when quality >= 90`
`376`	`376`	`* @VIPS_FOREIGN_SUBSAMPLE_ON: always perform subsampling`
`377`	`377`	`* @VIPS_FOREIGN_SUBSAMPLE_OFF: never perform subsampling`
`378`	`378`	`*`