Hi Gabriel,

I've successfully done what you're trying to do I think. I wrote about some problems in the following thread: https://groups.google.com/forum/#!topic/boost-list/4CqibxPFdUw. In short, I had to specialize a few other metafunctions. I think we should add a scoped_integral_channel_value type which has appropriate specializations for people trying to do what you're doing.

I had to make the following change to compile with c++11 clang:

diff --git a/include/boost/gil/channel_algorithm.hpp b/include/boost/gil/channel_algorithm.hpp

index 1361219..1799470 100644

--- a/include/boost/gil/channel_algorithm.hpp

+++ b/include/boost/gil/channel_algorithm.hpp

@@ -51,7 +51,7 @@ template <typename SrcChannelV, typename DstChannelV, bool SrcLessThanDst, bool

template <typename UnsignedIntegralChannel>

-struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,-1> {};

+struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,(1<<sizeof(Un

template <>

struct unsigned_integral_max_value<uint8_t> : public mpl::integral_c<uint32_t,0xFF> {};

Then I added a couple specializations in your code:

#include <boost/gil/gil_all.hpp>

#include <cstdint>

using namespace std;

using namespace boost::gil;

namespace detail

{

struct bits14_min { static std::uint16_t apply() { return 0;} };

struct bits14_max { static std::uint16_t apply() { return 0x3FF;} };

}

typedef scoped_channel_value <std::uint16_t, ::detail::bits14_min, ::detail::bits14_max> bits14_t;

namespace boost { namespace gil { namespace detail {

template <> struct unsigned_integral_max_value<bits14_t> : public mpl::integral_c<uint32_t,0x3FF> {};

template <> struct unsigned_integral_num_bits<bits14_t> : public mpl::int_<14> {};

}}}

typedef pixel<bits14_t, gray_layout_t> Pixel1;

typedef image<Pixel1> Frame1;

int main()

{

bits14_t x = channel_traits<bits14_t>::max_value();

assert(x == 0x3ff);

bits16 y = channel_convert<bits16>(x);

assert(y == 0xffff);

Frame1 image(

Frame1::point_t(100, 100),

Frame1::value_type((1 << 14)-1),

0);

gray16_image_t image2(image.dimensions());

Frame1::view_t view1(view(image));

gray16_image_t::view_t view2(view(image2));

copy_and_convert_pixels(view1, view2);

return 0;

}

On Thu, Jan 8, 2015 at 4:13 PM, Gabriel Marcano <gabemarcano@yahoo.com> wrote:

I have been experimenting with Boost.GIL, and I have run into something
that I'm not sure if it's a problem on my end or with Boost.GIL. In
essence, I'm trying to make a grayscale image with channels limited to
14 bits. I am using scoped_channel_value to do this. The problem
happens when I try to convert the 14 bit image to a 16 bit grayscale
image I get compilation errors. I am including the code I am using
below:

//START CODE

#include <boost/gil/gil_all.hpp>
#include <cstdint>

using namespace std;
using namespace boost::gil;

namespace detail
{
struct bits14_min { static std::uint16_t apply() { return 0;} };
struct bits14_max
{ static std::uint16_t apply() { return 0x3FF;} };
}

typedef scoped_channel_value
<std::uint16_t,
::detail::bits14_min, ::detail::bits14_max> bits14_t;

typedef pixel<bits14_t, gray_layout_t> Pixel1;
typedef image<Pixel1> Frame1;

int main()
{
Frame1 image(
Frame1::point_t(100, 100),
Frame1::value_type((1 << 14)-1),
0);

gray16_image_t image2(image.dimensions());

Frame1::view_t view1(view(image));
gray16_image_t::view_t view2(view(image2));

copy_and_convert_pixels(view1, view2);

return 0;
}

//END CODE

The interesting thing is that the program compiles if change
typedef scoped_channel_value
<std::uint16_t,
::detail::bits14_min, ::detail::bits14_max> bits14_t;
to
typedef scoped_channel_value
<float,
::detail::bits14_min, ::detail::bits14_max> bits14_t;

I think the relevant error in the log is this:
/usr/include/boost/gil/channel_algorithm.hpp:54:8: error:
‘struct boost::gil::scoped_channel_value<short unsigned
int, detail::bits14_min, detail::bits14_max>’ is not a
valid type for a template non-type parameter
struct unsigned_integral_max_value : public
mpl::integral_c<UnsignedIntegralChannel,-1> {};

I am attaching the full compile log to this email. Thank you for any
help with this matter!

Sincerely,

Gabriel E. Marcano

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