LIBJPEG Question

[voyvoda .]

Hello, I am trying to implement bmp to jpeg encode application. I have used official STM code example. There is no compile error.

I gather RGB565 data from OV7670 camera. I can successfully write to SD card as 16 bit bitmap file and open it on a Windows PC. Colors sorting is like BGR. I save my file as 24 bit to encode jpeg. When I encode it to jpeg, I see that color sorting is not match with bmp file.

Jpeg sorting is RGB

bmp sorting is BGR

How can I solve this issue ?

In addition, do I need to convert my raw data from 16bit to 24bit for encoding to jpeg ?

Can I convert 16 bit bmp file to 16 bit jpeg file ? , If so, How can I ?

 Best Regards

void bmp2jpeg(void)
{
	   static struct jpeg_compress_struct cinfo;
	   /* This struct represents a JPEG error handler */
	   static struct jpeg_error_mgr jerr;
       /* Encode BMP Image to JPEG */
       JSAMPROW row_pointer;    /* Pointer to a single row */
       uint32_t bytesread;
       uint32_t index;
 
 
 
    /*##-3- Register the file system object to the FatFs module ##############*/
    if(f_mount(&fs, "", 0) == FR_OK)
    {
      /*##-4- Create and Open a new jpg image file with write access #########*/
      if(f_open(&MyFile1, "image.jpg", FA_CREATE_ALWAYS | FA_WRITE) == FR_OK)
      {
        /*##-5- Open the BMP image with read access ##########################*/
        if(f_open(&MyFile, "image.bmp", FA_READ) == FR_OK)
        {
          /*##-6- Jpeg encoding ##############################################*/
          //jpeg_encode(&MyFile, &MyFile1, 240, 320, 90, _aucLine);
 
          /* Step 1: allocate and initialize JPEG compression object */
          /* Set up the error handler */
          cinfo.err = jpeg_std_error(&jerr);
 
          /* Initialize the JPEG compression object */
          jpeg_create_compress(&cinfo);
 
          /* Step 2: specify data destination */
          jpeg_stdio_dest(&cinfo, &MyFile1);
 
          /* Step 3: set parameters for compression */
          cinfo.image_width = 320;
          cinfo.image_height = 240;
          cinfo.input_components = 3;
          cinfo.in_color_space = JCS_RGB;
 
          /* Set default compression parameters */
          jpeg_set_defaults(&cinfo);
 
          cinfo.dct_method  = JDCT_FLOAT;
 
          jpeg_set_quality(&cinfo, 90, TRUE);
 
          /* Step 4: start compressor */
          jpeg_start_compress(&cinfo, TRUE);
 
          /* Get bitmap data address offset */
          f_read(&MyFile, _aucLine, 14, (UINT*)&bytesread);
          index = *(__IO uint16_t *) (_aucLine + 10);
          index |= (*(__IO uint16_t *) (_aucLine + 12)) << 16;
 
          while (cinfo.next_scanline < cinfo.image_height)
          {
            /* In this application, the input file is a BMP, which first encodes the bottom of the picture */
            /* JPEG encodes the highest part of the picture first. We need to read the lines upside down   */
            /* Move the read pointer to 'last line of the picture - next_scanline'    */
            f_lseek(&MyFile, ((cinfo.image_height-1-cinfo.next_scanline)*320*3)+index);
            if(f_read(&MyFile, _aucLine, 320*3, (UINT*)&bytesread) == FR_OK)
            {
              row_pointer = (JSAMPROW)_aucLine;
              jpeg_write_scanlines(&cinfo, &row_pointer, 1);
            }
          }
 
          /* Step 5: finish compression */
          jpeg_finish_compress(&cinfo);
 
          /* Step 6: release JPEG compression object */
          jpeg_destroy_compress(&cinfo);
 
 
          /* Close the BMP and JPEG files */
          f_close(&MyFile1);
          f_close(&MyFile);
 
        }
        else
        {
          Error_Handler();
        }
      }
      else
      {
        Error_Handler();
      }
    }
    else
    {
      Error_Handler();
    }
 
}