Re: [Boost-users] [GIL] How to read fixed point channel ?

Subject: Re: [Boost-users] [GIL] How to read fixed point channel ?
From: Christian Henning (chhenning_at_[hidden])
Date: 2009-11-26 15:33:48

Eloi,

maybe you have to create new channel type which represents a fixed
point value. A good starting point might be scoped_channel_value in
channel.hpp. I'm thinking something like this:

template< typename BaseChannelValue >
class fixed_point
{
    typedef fixed_point       value_type;
    typedef value_type&       reference;
    typedef value_type*       pointer;
    typedef const value_type& const_reference;
    typedef const value_type* const_pointer;

    BOOST_STATIC_CONSTANT(bool,
is_mutable=channel_traits<BaseChannelValue>::is_mutable);

    static value_type min_value() { return ; }
    static value_type max_value() { return ; }

    fixed_point() {}
    fixed_point(const fixed_point& c) : _value(c._value) {}
    fixed_point(BaseChannelValue val) : _value(val) {}

    fixed_point& operator++() { /*todo*/; return *this; }
    fixed_point& operator--() { /*todo*/; return *this; }

    fixed_point operator++(int) { fixed_point tmp=*this;
this->operator++(); return tmp; }
    fixed_point operator--(int) { fixed_point tmp=*this;
this->operator--(); return tmp; }

    template <typename Scalar2> fixed_point& operator+=(Scalar2 v) {
/*todo*/; return *this; }
    template <typename Scalar2> fixed_point& operator-=(Scalar2 v) {
/*todo*/; return *this; }
    template <typename Scalar2> fixed_point& operator*=(Scalar2 v) {
/*todo*/; return *this; }
    template <typename Scalar2> fixed_point& operator/=(Scalar2 v) {
/*todo*/; return *this; }

    fixed_point& operator=(BaseChannelValue v) { _value=v; return *this; }
    operator BaseChannelValue() const { return _value; }

private:

    BaseChannelValue _value;
};

Does that goes in your direction?

Regards,
Christian

On Thu, Nov 26, 2009 at 5:24 AM, Eloi Du Bois <eloi.du.bois_at_[hidden]> wrote:
> Hi,
>
> I have a stream with 8.8 (16b) channels encoded with fixed point arithmetics
> (http://knol.google.com/k/anonymous/fixed-point-arithmetic/1b19ktdbl6g9q/2#)
> and I need to create a rgb16 view that can hold my image... I tried with
> interleaved_view but this makes wrong values. I don't know how to manage
> with this...
> How must be encoded the shorts in a rgb16_image_t ?
>
> If anyone could help me, that would be great.
>
> Thanks,
> Eloi.
>
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