Image descriptors

[syg19]

Hello, well I'm new at programming and C++, but for a program I am developing I need to use an image descriptor for a function that gets the RGB values from the image descriptor (the functions are from http://www.catenary.com) anyway I'm not sure I'm understanding everything about an image descriptor. I have read a few things about them and understand that they contain information about the image. It seems in the sample code I'm using though the image descriptor is never intialized. I need to have the image descriptor referring to an image on file (more specifically I need it to access the last photo saved by my program but that's not really relevant). So can anyone describe a way to do this or if this is even how image descriptors work?

[syg19]

int loadjpgfilefrombuffer(LPTSTR fname, imgdes *image)
   {
   #define BAD_READ -87
   
   JpegData jdat;      // Reserve space for struct
   DWORD bytesRead, 
   int rcode = NO_ERROR;
   OFSTRUCT of_st;
   UCHAR huge *jpegbuff;
   HANDLE fhandle;
   DWORD filesize;
   
   // Load JPEG file into buffer
   fhandle = CreateFile(fname, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_ NORMAL, NULL);
   if(fhandle == INVALID_HANDLE_VALUE)
      return(BAD_OPN);
   // Get filesize
   filesize = GetFileSize(fhandle, NULL);

   CloseHandle(fhandle);  // Close the file
   
   // Allocate memory to hold file
   jpegbuff = (UCHAR huge *)GlobalAllocPtr(GMEM_MOVEABLE, filesize);
   if(jpegbuff == 0)
      return(BAD_MEM);   // Allocation failed!
      
   // Load JPEG file into memory
   fhandle = CreateFile(fname, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_ NORMAL, NULL);
   if(fhandle == INVALID_HANDLE_VALUE)
      return(BAD_OPN);

   ReadFile(fhandle, jpegbuff, filesize, &bytesRead, NULL);
   if(bytesRead == 0)
      rcode = BAD_READ;
   CloseHandle(fhandle);  // Close the file
   
   // Read the JPEG data from the buffer
   // Make sure JPEG data exists and get image dimensions
   rcode = jpeginfofrombuffer(jpegbuff, &jdat);
   if(rcode == NO_ERROR) {
      // Release the current image buffer
      freeimage(image);
      // Allocate the new image buffer to the file dimensions
      // This allocates a DIB to hold the image
      rcode = allocimage(image, jdat.width, jdat.length, jdat.vbitcount);
      if(rcode == NO_ERROR) {
         // Decompress the JPEG data
         rcode = loadjpgfrombuffer(jpegbuff, image);
         }   
      }
   GlobalFreePtr(jpegbuff); // Free allocated memory
   // Now the image is in the DIB and ready to process, display, or print
   return(rcode);
}

this is the sample code I was given that I am currently trying to get to work but it is saying image unitialized

[VictorN]

this is the sample code I was given that I am currently trying to get to work but it is saying image unitialized

Who (or what) a where is saying "image unitialized"?
Besides, why are you closing the file and then opening it again with the same attributes?

[syg19]

Well the program compiles fine but when I try to take a picture (which is the action that initiates this code) I get an error message saying "Run-Time Check Failure #3 - The variable 'image' is being used without being initialized." As to your other question I don't really know I'm trying to use image processing tools provided by catenary.com this is a "sample" code they provide which I'm trying to get to work before.