Re: [Boost-users] [GIL] any_image difference

Subject: Re: [Boost-users] [GIL] any_image difference
From: Olivier Tournaire (olitour_at_[hidden])
Date: 2010-11-06 10:44:53

Hi,

2010/11/5 Olivier Tournaire <olitour_at_[hidden]>

> Hi all,
>
> What is the best way to compute the difference between 2 any_image? Of
> course, the input any_image may not be of the same type... So, if pixels are
> unsigned int for the 1st one and double for the 2nd one, the result must be
> stored as double.
> I (accidently) found pixel_minus_t in pixel_numeric_operations.hpp but
> cannot figure how to use it.
>

I am still having problem with this. I found a way to write such an image
difference, but not for any_image. Here is what I have now:

   namespace boost { namespace gil {

typedef double bits64F;

GIL_DEFINE_BASE_TYPEDEFS(64F,gray)

 typedef float bits32F;

GIL_DEFINE_BASE_TYPEDEFS(32F,gray)

} }

  struct image_difference

{

    typedef void result_type;

     template<typename OutputViewType, typename ViewType1, typename ViewType2>

    result_type operator()(OutputViewType &out, const ViewType1 &v1,
const ViewType2 &v2) const

    {

         typedef typename get_pixel_type<ViewType1>::type      v1_pixel_t;

        typedef typename get_pixel_type<ViewType2>::type      v2_pixel_t;

        typedef typename get_pixel_type<OutputViewType>::type out_pixel_t;

         typename ViewType1::iterator      v1_it = v1.begin();

        typename ViewType2::iterator      v2_it = v2.begin();

        typename OutputViewType::iterator out_it = out.begin();

         for(;v1_it!=v1.end();++v1_it, ++v2_it, ++out_it)

            *out_it = pixel_minus_t<v1_pixel_t, v2_pixel_t,
out_pixel_t>()(*v1_it, *v2_it);

    }

};

int main(int argc, char** argv)

{

     gray16s_image_t mns;

    gray32F_image_t mnt, mne;

     read_image(
"/home/olivier/work/data/ZTerrain_c3/ZTerrain_c3.tif", mns ,
tiff_tag() );

    read_image(
"/home/olivier/work/data/ZTerrain_c3/ZTerrain_c3_MNT.tif", mnt ,
tiff_tag() );

     mne.recreate( mns.width(), mns.height() );

    image_difference()( view(mne) , view(mns) , view(mnt) );

     write_view(
"/home/olivier/work/data/ZTerrain_c3/ZTerrain_c3_MNE.tif", view(mne),
tiff_tag() );

}

 I am however sure there is a generic and better way to do such a simple
image operation. 2 questions arise:

1) how can I use for_each_pixel in image_difference rather than a for loop?
2) how can I extend this code to work on any_image(_view) using
apply_operation?

Best regards,

Olivier