How to compress a RGB image to jpeg with libjpeg

kevin_hector — Thu, 02 Jul 2020 14:49:05 GMT

I'm working on a i.MX.RT 1060 and I try to convert a RGB image coming from a camera to a jpeg image. But I don't succeed to do that because when the code arrived at the line "jpeg_start_compress(&cinfo, TRUE);" the i.MX.RT a problem is generated.

Who can help me ? Thank you for your futur help.

I put below my code :

void encode_jpeg_to_memory(unsigned char* image, int width, int height, int quality,
const char* comment, unsigned long* jpegSize, unsigned char** jpegBuf)

{
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;

JSAMPROW row_pointer[1];
int row_stride;

cinfo.err = jpeg_std_error(&jerr);

jpeg_create_compress(&cinfo);

cinfo.image_width = width;
cinfo.image_height = height;

cinfo.input_components = 3;
cinfo.in_color_space = JCS_RGB;

jpeg_set_defaults(&cinfo);

jpeg_set_quality(&cinfo, quality, TRUE);

jpeg_mem_dest(&cinfo, jpegBuf, jpegSize);

jpeg_start_compress(&cinfo, TRUE);

if (comment)

{
jpeg_write_marker(&cinfo, JPEG_COM, (const JOCTET*)comment, strlen(comment));
}

row_stride = width*3;

// Encode

while (cinfo.next_scanline < cinfo.image_height)

   {
      row_pointer[0] = &image[cinfo.next_scanline * row_stride];
      jpeg_write_scanlines(&cinfo, row_pointer, 1);
   }

jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
}

Re: How to compress a RGB image to jpeg with libjpeg

Sabina_Bruce — Mon, 06 Jul 2020 16:09:05 GMT

Hello Kevin,

Hope you are doing well.

I recommend that you use the Developing a Camera Application with iMXRT Series. This application note includes source code that you may use as a reference. You will find that this example captures images compresses the jpeg and saves it to an SD card.

Best Regards,

Sabina

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topic Re: How to compress a RGB image to jpeg with libjpeg in i.MX RT Crossover MCUs

How to compress a RGB image to jpeg with libjpeg

Re: How to compress a RGB image to jpeg with libjpeg