Convert from YUV to RGB in c++ (android-ndk)

Question

Im developing in android, and want to convert the byte-array from the camera's previewCallback, which is in YUV-format, to rgb-format.

I have used the function given in this answer: Getting frames from Video Image in Android

It works perfectly in java, but my problem is that I want to make the function in c++ (I'm using the ndk, and not very familiar with c++).

I have tried to create the function in c++, but it always makes strange results (eg the picture is all green).

Does anyone have a similar function or this function working in c++?

Thanks.

Answer 1

Look at this: http://pastebin.com/mDcwqJV3

Fixed-point conversion from YUYV to RGB24

Also, some cameras return raw images in 'UYVY' byte orger, so make corresponding changes in the conversion function.

Answer 2

Conversion from YUYV to RGB in C++:

unsigned char* rgb_image = new unsigned char[width * height * 3]; //width and height of the image to be converted

int y;
int cr;
int cb;

double r;
double g;
double b;

for (int i = 0, j = 0; i < width * height * 3; i+=6 j+=4) {
    //first pixel
    y = yuyv_image[j];
    cb = yuyv_image[j+1];
    cr = yuyv_image[j+3];

    r = y + (1.4065 * (cr - 128));
    g = y - (0.3455 * (cb - 128)) - (0.7169 * (cr - 128));
    b = y + (1.7790 * (cb - 128));

    //This prevents colour distortions in your rgb image
    if (r < 0) r = 0;
    else if (r > 255) r = 255;
    if (g < 0) g = 0;
    else if (g > 255) g = 255;
    if (b < 0) b = 0;
    else if (b > 255) b = 255;

    rgb_image[i] = (unsigned char)r;
    rgb_image[i+1] = (unsigned char)g;
    rgb_image[i+2] = (unsigned char)b;

    //second pixel
    y = yuyv_image[j+2];
    cb = yuyv_image[j+1];
    cr = yuyv_image[j+3];

    r = y + (1.4065 * (cr - 128));
    g = y - (0.3455 * (cb - 128)) - (0.7169 * (cr - 128));
    b = y + (1.7790 * (cb - 128));

    if (r < 0) r = 0;
    else if (r > 255) r = 255;
    if (g < 0) g = 0;
    else if (g > 255) g = 255;
    if (b < 0) b = 0;
    else if (b > 255) b = 255;

    rgb_image[i+3] = (unsigned char)r;
    rgb_image[i+4] = (unsigned char)g;
    rgb_image[i+5] = (unsigned char)b;
}

This method assumes that your yuyv_image is an unsigned char* as well.

More information on YUYV can be found here

And for more clarification on YUYV --> RGB check out this