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First bit of getting alpha channels saved in TIFF files. The Extra Samples tag is now set.

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This commit is contained in:
William Gallafent
2014-05-19 22:14:30 +01:00
committed by Stefan Seefeld
parent 5b2e3ef0c7
commit 85a02eaade
2 changed files with 14 additions and 3 deletions
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11
include/boost/gil/extension/io/formats/tiff/writer_backend.hpp
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@@ -19,6 +19,8 @@
///
////////////////////////////////////////////////////////////////////////////////////////
#include <boost/mpl/contains.hpp>
#include <boost/gil/extension/io/tiff_tags.hpp>
namespace boost { namespace gil {
@@ -58,11 +60,10 @@ protected:
// get the type of the first channel (heterogeneous pixels might be broken for now!)
typedef typename channel_traits< typename element_type< pixel_t >::type >::value_type channel_t;
typedef typename color_space_type< View >::type color_space_t;
if(! this->_info._photometric_interpretation_user_defined )
{
typedef typename color_space_type< View >::type color_space_t;
// write photometric interpretion - Warning: This value is rather
// subjective. The user should better set this value itself. There
// is no way to decide if a image is PHOTOMETRIC_MINISWHITE or
@@ -87,6 +88,12 @@ protected:
tiff_samples_per_pixel::type samples_per_pixel = num_channels< pixel_t >::value;
this->_io_dev.template set_property<tiff_samples_per_pixel>( samples_per_pixel );
// The other half of the story is that it needs to be premultiplied on the way into the file.
if (boost:: mpl:: contains <color_space_t, alpha_t>:: value) { // the pixel type includes alpha_t
this->_info._extra_sample_value = EXTRASAMPLE_ASSOCALPHA;
this->_info._extra_samples = &(this->_info._extra_sample_value);
this->_io_dev.template set_property<tiff_extra_samples>( this->_info._extra_samples );
}
// write bits per sample
// @todo: Settings this value usually requires to write for each sample the bit
// value seperately in case they are different, like rgb556.

6
include/boost/gil/extension/io/tiff_tags.hpp
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@@ -286,6 +286,7 @@ struct image_write_info< tiff_tag, Log >
, _tile_length ( 0 )
, _x_resolution ( 0 )
, _y_resolution ( 0 )
, _extra_samples ( 0 )
{}
/// The color space of the image data.
@@ -310,7 +311,10 @@ struct image_write_info< tiff_tag, Log >
tiff_x_resolution::type _x_resolution;
tiff_y_resolution::type _y_resolution;
/// A log to transcript error and warning messages issued by libtiff.
/// Extra Sample type (for alpha)
tiff_extra_samples::type _extra_samples;
uint16_t _extra_sample_value;
/// A log to transcript error and warning messages issued by libtiff.
Log _log;
};