How can I print 16-bit grayscale image in SDL? - c

Question

I have a structure which contains 16-bit grayscale image from scientific camera, structure is like this:
struct qscam_image {
int row;
int col;
int max_gray; // this should be 65535
unsigned short *data;
};
Then I have program which should display updated grayscale image each second or so (depending on time which takes to transfer data from camera).
#include <GL/gl.h>
#include <GL/glu.h>
#include "qscapi.h"
#include <SDL/SDL.h>
static void render(SDL_Surface * sf)
{
SDL_Surface * screen = SDL_GetVideoSurface();
if(SDL_BlitSurface(sf, NULL, screen, NULL) == 0)
SDL_UpdateRect(screen, 0, 0, 0, 0);
}
int main(int argc, char **argv)
{
//initialize camera
struct qscam_image *image = NULL;
qscam_create_image(&image);
qscam_init();
//initialize SDL
SDL_Event ev;
int active;
/* Initialize SDL */
if(SDL_Init(SDL_INIT_VIDEO) != 0)
fprintf(stderr,"Could not initialize SDL: %s\n",SDL_GetError());
SDL_SetVideoMode(1900, 1080, 24, SDL_HWSURFACE);
/* Main loop */
active = 1;
while(active)
{
/* Handle events */
while(SDL_PollEvent(&ev))
{
if(ev.type == SDL_QUIT)
active = 0; /* End */
}
qscam_get_image(0.030, &image); //get image from camera
/* create the image variable */
Uint32 mask = 0xff00; // gray
SDL_Surface* print_image = SDL_CreateRGBSurfaceFrom
(image->data, image->col, image->row,
16, image->col*2, mask, mask, mask, 0);
render(print_image);
}
/* Exit */
qscam_disconnect();
qscam_destroy_image(&image);
SDL_Quit();
return 0;
}
It works to some extent, with mask=0x00ff it displays random noise but that is only 8-bit image. With mask=0xffff nothing is displayed and with mask=0xff00 again image is displayed, but in a way that leads me to think that the image matrix should be transposed.
First question: What is the proper way to display 16-bit grayscale image (which is in memory saved as unsigned short[]) using SDL and c?
And second question: Is there any easy way to transpose image matrix with SDL or do I have to write separate function?