Brightening:

Just add an offset to the original image's pixel components[Red,Green,Blue] and then make it look like really bright. Please tweak with the value of offset to get a decent level of brightness.

        pixel.red   += offset;
        pixel.green += offset;
        pixel.blue  += offset;

some one please fix it! This effect is really bad!

#include<gtk/gtk.h>


void colorbright_picture(GdkPixbuf *pb,int offset)
{ 
  int ht,wt;
  int i=0,j=0;
  int rowstride=0;  
  int bpp=0;
  gchar *pixel;


  if(gdk_pixbuf_get_bits_per_sample(pb)!=8)   //we handle only 24 bit images.
  	return;                               //look at 3 bytes per pixel.

  bpp=3;	         	  //getting attributes of height,
  ht=gdk_pixbuf_get_height(pb);   //width, and bpp.Also get pointer
  wt=gdk_pixbuf_get_width(pb);	  //to pixels.
  pixel=gdk_pixbuf_get_pixels(pb);
  rowstride=wt*bpp;

  for(i=0;i<ht;i++)		//iterate over the height of image.
    for(j=0;j<rowstride;j+=bpp)   //read every pixel in the row.skip
				//bpp bytes 
      {	    

	//Manipulate Red.
	if((pixel[i*rowstride + j+0]+offset) >= 0xff)
	  {
	    pixel[i*rowstride + j+0]=0xff;
	  }
	else if((pixel[i*rowstride + j+0]-offset) < 0)
	  {
	    pixel[i*rowstride + j+0]=0;
	  }
	else
	  pixel[i*rowstride + j+0]+=offset;


	//Manip Green
	if((pixel[i*rowstride + j+1]+offset) >= 0xff)
	  {
	    pixel[i*rowstride + j+1]=0xff;
	  }
	else if((pixel[i*rowstride + j+1]-offset) < 0)
	  {
	    pixel[i*rowstride + j+1]=0;
	  }
	else
	  pixel[i*rowstride + j+1]+=offset;


	//Manip Blue	
	if((pixel[i*rowstride + j+2]+offset) >= 0xff)
	  {
	    pixel[i*rowstride + j+2]=0xff;
	  }
	else if((pixel[i*rowstride + j+2]-offset) < 0)
	  {
	    pixel[i*rowstride + j+2]=0;
	  }
	else
	  pixel[i*rowstride + j+2]+=offset;
      }
  return;
}
% <!-- provide link here-->
% complete working example with glue code in example_bright.c