Problems using OpenCV with ZBar in C - c

Question

I'm trying to use OpenCV to load a jpg image from file and pass it to zbar library to decode a barcode. However, no barcodes are decoded properly, even though the code below works when I use functions from libpng to load the image. I have no errors, and I have no idea where the problem is, as I have already checked all posts I could find and nothing worked.
Thanks in advance.
#include <stdio.h>
#include <stdlib.h>
#include <zbar.h>
#include <cv.h>
#include <highgui.h>
#include <math.h>
zbar_image_scanner_t *scanner = NULL;
IplImage* cvLoadImage(const char* filename, int iscolor);
int main (int argc, char **argv)
{
// create a reader
scanner = zbar_image_scanner_create();
// configure the reader
zbar_image_scanner_set_config(scanner, 0, ZBAR_CFG_ENABLE, 1);
// obtain image data with opencv
IplImage* img = 0;
int height,width,step,channels;
img = cvLoadImage(argv[1], 1);
height = img->height;
width = img->width;
step = img->widthStep;
channels = img->nChannels;
void *raw = (void *)(img->imageData);
printf("Processing a %dx%d image \n",height,width);
// wrap image data
zbar_image_t *image = zbar_image_create();
zbar_image_set_format(image, *(int*)"Y800");
zbar_image_set_size(image, width, height);
zbar_image_set_data(image, raw, width * height, zbar_image_free_data);
// scan the image for barcodes
int n = zbar_scan_image(scanner, image);
if (n==0){
printf("No barcode detected for image %s\n", argv[1]);
return 1;
}
// extract results
if (n!=0) {
const zbar_symbol_t *symbol = zbar_image_first_symbol(image);
printf("symbol extracted \n");
for(; symbol; symbol = zbar_symbol_next(symbol)) {
// do something useful with results
zbar_symbol_type_t typ = zbar_symbol_get_type(symbol);
const char *dataZ = zbar_symbol_get_data(symbol);
printf("decoded %s symbol \"%s\" of image %s \n", zbar_get_symbol_name(typ), dataZ, argv[1]);
}
}
// clean up
zbar_image_destroy(image);
zbar_image_scanner_destroy(scanner);
return 0;
}

Answer 1

That code worked perfectly for me. I used it in my program with small changes:
I don't show how I get the 'struct _IplImage *' {aka 'IplImage *'} because it is done in another file, and get it as param, but it is of course done with cvLoadImage().
I used "GREY" instead of "Y800", but I tried "Y800" and also worked, as they are fundamentally the same.
This works (at least with openCV 2.4.9; openCV is deprecating its C API, and its C++ API should be used instead (I'm against this, but nothing can be done :( )):
/******************************************************************************
******* headers **************************************************************
******************************************************************************/
/* Standard C ----------------------------------------------------------------*/
/* snprintf() */
#include <stdio.h>
/* Packages ------------------------------------------------------------------*/
/* opencv */
#include <cv.h>
/* zbar */
#include <zbar.h>
/* Module --------------------------------------------------------------------*/
#include "this_file.h"
/******************************************************************************
******* macros ***************************************************************
******************************************************************************/
# define ZB_CODES_MAX (10)
# define ZBAR_LEN_MAX (1048576)
/******************************************************************************
******* structs **************************************************************
******************************************************************************/
struct ZB_Codes {
int n;
struct {
int type;
char sym_name [80];
char data [ZBAR_LEN_MAX];
} arr [ZB_CODES_MAX];
};
/******************************************************************************
******* variables ************************************************************
******************************************************************************/
struct ZB_Codes zb_codes;
/******************************************************************************
******* functions ************************************************************
******************************************************************************/
void img_zb_decode (struct _IplImage *imgptr)
{
struct zbar_image_scanner_s *scanner;
struct zbar_image_s *image_zb;
const struct zbar_symbol_s *symbol;
/* Type of code to scan */
/* 0 for all; set to another if used only for a specific barcode */
int code_type;
code_type = 0;
/* create & configure a reader */
scanner = zbar_image_scanner_create();
zbar_image_scanner_set_config(scanner, code_type, ZBAR_CFG_ENABLE, 1);
/* wrap image data */
image_zb = zbar_image_create();
zbar_image_set_format(image_zb, *(int *)"GREY");
zbar_image_set_size(image_zb, imgptr->width, imgptr->height);
zbar_image_set_data(image_zb, (void *)(imgptr->imageData),
(imgptr->width * imgptr->height), NULL);
/* scan the image for barcodes */
int i;
zb_codes.n = zbar_scan_image(scanner, image_zb);
if (zb_codes.n) {
/* extract results */
symbol = zbar_image_first_symbol(image_zb);
for (i = 0; i < ZB_CODES_MAX && symbol; i++) {
/* Write results into array */
zb_codes.arr[i].type = zbar_symbol_get_type(symbol);
snprintf(zb_codes.arr[i].sym_name, 80, "%s",
zbar_get_symbol_name(
zb_codes.arr[i].type));
snprintf(zb_codes.arr[i].data, ZBAR_LEN_MAX, "%s",
zbar_symbol_get_data(symbol));
/* Load next symbol */
symbol = zbar_symbol_next(symbol);
}
}
/* clean up */
zbar_image_destroy(image_zb);
zbar_image_scanner_destroy(scanner);
}
/******************************************************************************
******* end of file **********************************************************
******************************************************************************/