Method of processing pixel of image

1.
Include file:

#include <wx/rawbmp.h>

Pre defination:

typedef wxPixelData<wxBitmap, wxNativePixelFormat> PixelData;

Code example:

unsigned char grey = 0;

wxBitmap* m_pbmp = new wxBitmap(wxT("name.bmp"), wxBITMAP_TYPE_BMP);
PixelData data(*m_pbmp);
PixelData::Iterator p(data);
p.Offset(data, 0, 0);

for ( int y = 0; y < data.GetHeight(); y++ )
{
    PixelData::Iterator rowStart = p;

    for ( int x = 0; x < data.GetWidth(); x++, p++ )
    {
            grey = (unsigned char)(0.212671*p.Red() + 0.715160*p.Green() +                   0.072169*p.Blue());
            p.Red() = (unsigned char)grey;
            p.Green() = (unsigned char)grey;
            p.Blue() = (unsigned char)grey;
    }

    p = rowStart;
    p.OffsetY(data, 1);
}

2.

Include file: None. Pre defination: None. Code example:

wxImage temp_wxImage;
unsigned char* manipulator = NULL;
manipulator = temp_wxImage.GetData();
int width = temp_wxImage.GetWidth();
int height = temp_wxImage.GetHeight(); 
int grey = 0;
for(int j = 0; j < height; j++)
    for(int i = j*3*width; i < (j+1)*3*width; i+=3)
    {
            grey = (unsigned char)(0.212671*manipulator[i] + 
                    0.715160*manipulator[i+1] + 0.072169*manipulator[i+2]);
            manipulator[i] = grey;
            manipulator[i+1] = grey;
            manipulator[i+2] = grey;
    }

or

wxImage temp_wxImage;
unsigned char* manipulator = NULL;
manipulator = temp_wxImage.GetData();
int width = temp_wxImage.GetWidth();
int height = temp_wxImage.GetHeight(); 
int grey = 0;
for(int j = 0; j < height; j++)
    for(int i = 0; i < width; i++)
    {
            grey = (unsigned char)(0.212671*manipulator[(i+j*width)*3] +
                                   0.715160*manipulator[(i+j*width)*3+1] + 
                                   0.072169*manipulator[(i+j*width)*3+2]);
            manipulator[(i+j*width)*3] = grey;
            manipulator[(i+j*width)*3+1] = grey;
            manipulator[(i+j*width)*3+2] = grey;
    }