don't set JFIF res if we will set EXIF res
Some JPEG loaders give priority to JFIF resolution over EXIF resolution tags. This patch makes libvips not write the JFIF res tags if it will be writing the EXIF res tags. See https://github.com/libvips/ruby-vips/issues/247
This commit is contained in:
John Cupitt
parent
801111a2fa
commit
348e5e1523
@ -1,6 +1,7 @@
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6/9/20 started 8.10.2
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- update magicksave/load profile handling [kelilevi]
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- better demand hint rules [kaas3000]
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- in jpegsave, don't set JFIF resolution if we set EXIF resolution
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9/8/20 started 8.10.1
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- fix markdown -> xml conversion in doc generation
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@ -108,6 +108,8 @@
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* - revise for source IO
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* 5/5/20 angelmixu
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* - better handling of JFIF res unit 0
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* 13/9/20
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* - set resolution unit from JFIF
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*/
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/*
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@ -506,6 +508,13 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
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break;
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}
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#ifdef DEBUG
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if( cinfo->saw_JFIF_marker )
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printf( "read_jpeg_header: jfif _density %d, %d, unit %d\n",
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cinfo->X_density, cinfo->Y_density,
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cinfo->density_unit );
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#endif /*DEBUG*/
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/* Get the jfif resolution. exif may overwrite this later. Default to
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* 72dpi (as EXIF does).
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*/
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@ -514,12 +523,6 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
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if( cinfo->saw_JFIF_marker &&
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cinfo->X_density != 1U &&
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cinfo->Y_density != 1U ) {
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#ifdef DEBUG
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printf( "read_jpeg_header: jfif _density %d, %d, unit %d\n",
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cinfo->X_density, cinfo->Y_density,
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cinfo->density_unit );
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#endif /*DEBUG*/
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switch( cinfo->density_unit ) {
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case 0:
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/* X_density / Y_density gives the pixel aspect ratio.
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@ -535,6 +538,8 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
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*/
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xres = cinfo->X_density / 25.4;
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yres = cinfo->Y_density / 25.4;
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vips_image_set_string( out,
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VIPS_META_RESOLUTION_UNIT, "in" );
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break;
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case 2:
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@ -542,6 +547,8 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
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*/
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xres = cinfo->X_density / 10.0;
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yres = cinfo->Y_density / 10.0;
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vips_image_set_string( out,
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VIPS_META_RESOLUTION_UNIT, "cm" );
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break;
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default:
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@ -94,6 +94,8 @@
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* - revise for target IO
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* 18/2/20 Elad-Laufer
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* - add subsample_mode, deprecate no_subsample
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* 13/9/20
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* - only write JFIF resolution if we don't have EXIF
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*/
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/*
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@ -412,6 +414,59 @@ write_profile_data (j_compress_ptr cinfo,
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}
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}
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#ifndef HAVE_EXIF
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/* Set the JFIF resolution from the vips xres/yres tags.
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*/
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static void
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vips_jfif_resolution_from_image( struct jpeg_compress_struct *cinfo,
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VipsImage *image )
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{
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int xres, yres;
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const char *p;
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int unit;
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/* Default to inches, more progs support it.
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*/
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unit = 1;
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if( vips_image_get_typeof( image, VIPS_META_RESOLUTION_UNIT ) &&
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!vips_image_get_string( image,
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VIPS_META_RESOLUTION_UNIT, &p ) ) {
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if( vips_isprefix( "cm", p ) )
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unit = 2;
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else if( vips_isprefix( "none", p ) )
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unit = 0;
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}
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switch( unit ) {
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case 0:
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xres = VIPS_RINT( image->Xres );
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yres = VIPS_RINT( image->Yres );
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break;
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case 1:
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xres = VIPS_RINT( image->Xres * 25.4 );
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yres = VIPS_RINT( image->Yres * 25.4 );
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break;
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case 2:
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xres = VIPS_RINT( image->Xres * 10.0 );
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yres = VIPS_RINT( image->Yres * 10.0 );
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break;
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default:
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g_assert_not_reached();
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break;
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}
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VIPS_DEBUG_MSG( "vips_jfif_resolution_from_image: "
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"setting xres = %d, yres = %d, unit = %d\n", xres, yres, unit );
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cinfo->density_unit = unit;
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cinfo->X_density = xres;
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cinfo->Y_density = yres;
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}
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#endif /*HAVE_EXIF*/
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/* Write an ICC Profile from a file into the JPEG stream.
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*/
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static int
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@ -643,18 +698,24 @@ write_vips( Write *write, int qfac, const char *profile,
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}
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}
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/* Don't write the APP0 JFIF headers if we are stripping.
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/* Only write the JFIF headers if we are not stripping and we have no
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* EXIF. Some readers get confused if you set both.
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*/
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if( strip )
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write->cinfo.write_JFIF_header = FALSE;
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write->cinfo.write_JFIF_header = FALSE;
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#ifndef HAVE_EXIF
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if( !strip ) {
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vips_jfif_resolution_from_image( &write->cinfo, write->in );
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write->cinfo.write_JFIF_header = TRUE;
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}
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#endif /*HAVE_EXIF*/
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/* Build compress tables.
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/* Write app0 and build compress tables.
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*/
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jpeg_start_compress( &write->cinfo, TRUE );
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/* Write any APP markers we need.
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/* All the other APP chunks come next.
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*/
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if( !strip ) {
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if( !strip ) {
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/* We need to rebuild the exif data block from any exif tags
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* on the image.
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*/
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