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Always getting bayer pattern

Submitted by jamcar23 on

Hey,

So I'm trying to use dcraw_make_mem_image and display the data as an Android Bitmap. Bitmaps expect ARGB at 8 bits per channel.

I start by calling method and pass in a Java string: 

// C
JNIEXPORT jbyteArray JNICALL
Java_xyz_jamescarroll_layer_NativeWrapper_extractRaw(JNIEnv *env, jclass type, jstring path_) {
    const char *path = (*env)->GetStringUTFChars(env, path_, 0);
    void *re = createClass(); // RawExtractor
    libraw_processed_image_t *image_t = extractPreview(path, re); 
    jbyteArray out = (*env)->NewByteArray(env, image_t->data_size);
 
    logProcessedImageInfo(image_t);
 
    (*env)->ReleaseStringUTFChars(env, path_, path);
    (*env)->SetByteArrayRegion(env, out, 0, image_t->data_size, (const jbyte *) image_t->data);
 
    destroyClass(re); // RawExtractor
 
    return out;
}

The above code creates a class called RawExtractor and calls RawExtractor::ExtractRgbBitmap. Then it set the data to a java byte array and returns the array.

// C++
libraw_processed_image_t* RawExtractor::extractRgbBitmap(const char *filename, int shouldProcess) {
    int err = 0;
 
    if (shouldProcess) {
        process(filename);
    }
 
    rgbBitmap = imgProc.dcraw_make_mem_image(&err);
 
    if (err != LIBRAW_SUCCESS) {
        LOGE("Can't copy image as RGB Bitmap %s: %s", filename, libraw_strerror(err));
    }
}
 
void RawExtractor::process(const char *filename) {
#define OUT imgProc.imgdata.params
    int err = 1;
 
    OUT.no_auto_bright = 1;
    OUT.use_auto_wb = 0;
    OUT.use_camera_wb = 1;
    OUT.output_color = 1;
    OUT.user_qual = 3;
    OUT.half_size = 1;
    OUT.output_bps = 8;
 
    if ((err = imgProc.open_file(filename)) != LIBRAW_SUCCESS) {
        LOGE("Can't open %s: %s", filename, libraw_strerror(err));
        return;
    }
 
    if ((err = imgProc.unpack()) != LIBRAW_SUCCESS) {
        LOGE("Can't unpack %s: %s", filename, libraw_strerror(err));
        return;
    }
    if ((err = imgProc.dcraw_process()) != LIBRAW_SUCCESS) {
        LOGE("Can't process %s: %s", filename, libraw_strerror(err));
        return;
    }
}

When the array is returned to java I convert the data (libraw_processed_image_t.data) to an int array of colors and create a bitmap. 

// Java
    public static Bitmap createFromColorChannels(byte[] channels, int width, int height) {
        int[] color = new int[channels.length / 3];
 
        for (int i = 0; i < color.length; i++) {
            color[i] = Color.rgb(channels[i], channels[i + 1], channels[i + 2]);
        }
 
        return Bitmap.createBitmap(color, width, height, Bitmap.Config.ARGB_8888);
    }

This seems to always create a bitmap with a bayer pattern: Original DNG vs Android Bitmap.

1.) Do you know why this might be happening?

2.) When calling dcraw_make_mem_image (or even copy_mem_image) the libraw_processed_image_t.data order is [R (0), G (0), B (0), R (1), G (1), B (1)] where (n) is the nth pixel, right? Does this change when the output is 16 bits since a char may only be 8 bits on some platforms? If so, what does the order look like?

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