sergiotarxz/libvips
sergiotarxz/libvips
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read jfif resolution

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read jfif, if available, before we read exif resolution
This commit is contained in:
John Cupitt 2012-01-09 10:34:47 +00:00
parent ae46447f5e
commit 774e2fe495
2 changed files with 51 additions and 2 deletions
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6
TODO
View File

@ -54,6 +54,12 @@
vips copy add[babe.jpg,add[babe2.jpg,babe3.jpg]] sum.v
perhaps use curly brackets for code?
vips max add{babe.jpg,babe2.jpg}
no brackets or square brackets for options

47
libvips/foreign/jpeg2vips.c
View File

@ -41,6 +41,8 @@
* - attach exif tags as coded values
* 24/11/11
* - turn into a set of read fns ready to be called from a class
* 9/1/12
* - read jfif resolution as well as exif
*/
/*
@ -389,10 +391,16 @@ set_vips_resolution( IMAGE *im, ExifData *ed )
break;
default:
vips_warn( "VipsJpeg", "%s", _( "bad resolution unit" ) );
vips_warn( "VipsJpeg",
"%s", _( "unknown EXIF resolution unit" ) );
return;
}
#ifdef DEBUG
printf( "set_vips_resolution: seen exif resolution %g, %g p/mm\n",
xres, yres );
#endif /*DEBUG*/
im->Xres = xres;
im->Yres = yres;
}
@ -529,6 +537,7 @@ read_jpeg_header( struct jpeg_decompress_struct *cinfo,
{
jpeg_saved_marker_ptr p;
VipsInterpretation interpretation;
double xres, yres;
/* Capture app2 sections here for assembly.
*/
@ -566,6 +575,40 @@ read_jpeg_header( struct jpeg_decompress_struct *cinfo,
break;
}
/* Get the jfif resolution. exif may overwrite this later.
*/
xres = 1.0;
yres = 1.0;
if( cinfo->saw_JFIF_marker &&
cinfo->X_density != 1U &&
cinfo->Y_density != 1U ) {
switch( cinfo->density_unit ) {
case 1:
/* Pixels per inch.
*/
xres = cinfo->X_density / 25.4;
yres = cinfo->Y_density / 25.4;
break;
case 2:
/* Pixels per cm.
*/
xres = cinfo->X_density / 10.0;
yres = cinfo->Y_density / 10.0;
break;
default:
vips_warn( "VipsJpeg",
"%s", _( "unknown JFIF resolution unit" ) );
break;
}
#ifdef DEBUG
printf( "read_jpeg_header: seen jfif resolution %g, %g p/mm\n",
xres, yres );
#endif /*DEBUG*/
}
/* Set VIPS header.
*/
vips_image_init_fields( out,
@ -573,7 +616,7 @@ read_jpeg_header( struct jpeg_decompress_struct *cinfo,
cinfo->output_components,
VIPS_FORMAT_UCHAR, VIPS_CODING_NONE,
interpretation,
1.0, 1.0 );
xres, yres );
/* Best for us, probably.
*/