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();
 }
 
}