Re: [boost] [GIL] trying to clean up a small block of adhoc code

From: Christian Henning (chhenning_at_[hidden])
Date: 2008-06-16 12:49:11

Michael,

here is my version of your algorithm. Please have a look:

std::vector<float> buffer( 1024 * 1024 );
//GenerateNoise( pBuffer, 1024, 1024 )

gray32f_view_t src = interleaved_view( 1024, 1024
                                     , (gray32f_pixel_t*) &buffer.front()
                                     , 1024 * 4 // bytes per scanline
                                     );

for( int y = 0; y < src.height(); ++y )
{
    gray32f_view_t::x_iterator src_it = src.row_begin( y );

    float ycopy = y;
    if(y > 511)
    {
        ycopy = 511 - std::abs( 512.f - ycopy );
    }

    for( int x = 0; x < src.width(); ++x )
    {
        float xcopy = x;

        if(x > 511)
        {
            xcopy = 511 - std::abs( 512.f - xcopy );
        }

        src_it[x] = src[xcopy][ycopy];
    }
}

I haven't really tested it, though. Most of the code you find in the
gil tutorial:

http://stlab.adobe.com/gil/html/giltutorial.html

Christian

On Mon, Jun 16, 2008 at 11:59 AM, Michael Marcin <mike.marcin_at_[hidden]> wrote:
> Hi,
>
> I've found a small block of adhoc image manipulation code written by someone
> in my current project.
>
> std::vector<float> pBuffer( 1024*1024 );
> GenerateNoise( pBuffer, 1024, 1024 )
> int n = 0;
> for(int y=0; y<1024; y++) {
>  for(int x=0; x<1024; x++) {
>    int xcopy = x, ycopy = y;
>    if(x > 511)
>      xcopy = 511 - CMath::Abs(512 - xcopy);
>    if(y > 511)
>      ycopy = 511 - CMath::Abs(512 - ycopy);
>    pBuffer[n] = pBuffer[ycopy*1024 + xcopy];
>    n++;
>  }
> }
>
>
> This takes the upper left corner and copies it to the upper right flipped
> horizontally, lower left flipper vertically, and lower right flipped
> horizontally and vertically.
>
> The code is poorly written but instead of trying to clean it up myself I
> thought this would be a good opportunity to learn to use gil.
>
> I think to get started I first need to create a gil image view from the raw
> data. Is this right?
>
> I looked at the image view from raw data function in the doxygen
> documentation but I don't see any for 1 channel data image data. Am I
> missing something?
>
> Thanks,
>
> Michael Marcin
>
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