Retrieving RGB value from CAM130

Hi All,

I have tried Camera Test function of 2440test.bin and it works properly.
But the problem is I don't know how to get RGB value nor YCrCb value of
each pixel. Is there anyone can help me?


Thanks,


Ito

The following 2 sets of formulae are taken from information from Keith
Jack's excellent book "Video Demystified" (ISBN 1-878707-09-4).
RGB to YUV Conversion

    Y  =      (0.257 * R) + (0.504 * G) + (0.098 * B) + 16

    Cr = V =  (0.439 * R) - (0.368 * G) - (0.071 * B) + 128

    Cb = U = -(0.148 * R) - (0.291 * G) + (0.439 * B) + 128


YUV to RGB Conversion

    B = 1.164(Y - 16)                   + 2.018(U - 128)

    G = 1.164(Y - 16) - 0.813(V - 128) - 0.391(U - 128)

    R = 1.164(Y - 16) + 1.596(V - 128)

In both these cases, you have to clamp the output values to keep them in
the [0-255] range

taken from mjpg-streamer source:

  z = 0;
  while (cinfo.next_scanline < vd->height) {
    int x;
    unsigned char *ptr = line_buffer;

    for (x = 0; x < vd->width; x++) {
      int r, g, b;
      int y, u, v;

      if (!z)
        y = yuyv[0] << 8;
      else
        y = yuyv[2] << 8;
      u = yuyv[1] - 128;
      v = yuyv[3] - 128;

      r = (y + (359 * v)) >> 8;
      g = (y - (88 * u) - (183 * v)) >> 8;
      b = (y + (454 * u)) >> 8;

      *(ptr++) = (r > 255) ? 255 : ((r < 0) ? 0 : r);
      *(ptr++) = (g > 255) ? 255 : ((g < 0) ? 0 : g);
      *(ptr++) = (b > 255) ? 255 : ((b < 0) ? 0 : b);

      if (z++) {
        z = 0;
        yuyv += 4;
      }
    }

Hi Kailas,

May be there is miscommunication. yeah, I know that formulas, but the
problem is I don't know how to get RGB or YCrCb data from camera, or I can
say that I don't know which register I have to access to get RGB data. Can
you help me ?


Regards,



Ito

Hi Kailas,


do you mean it takes from frame buffer ? That is for linux, but I want to
use my mini2440 without OS.


Regards


Ito

oh yes. I did not notice that you have posted your question under "Non OS"
section.

I personally prefer busybox linux as it takes very less memory and I get
comfort of using ready made utilities and drivers.  

Hope the attached file will help you to understand LCD I/O.  This file is
there in the CD/DVD came along with the board.

regards,

Kailas

Hai Kailas,

Thank you for the file. It's really help me



Regards,


Ito

CAMIF.C is not enough to view video from cam130