hi
I am working on an android program to process multiple frames
of camera images. I used the setPreviewCallbackWithBuffer
function and process the data inside the PreviewCallback. The
code works generally ok, except the resulting data have weird
values.
I set the camera picture format to RGB565, and then create
an int[] buffer, with the same size of the byte[] in a frame, and
taking accumulated image of the red-channel.
The following is my code:
public class NIRSActivity extends Activity {
int[] avg; // integer buffer to accumulate the red channel
int frame; // frame counter
public void onCreate(Bundle savedInstanceState) {
avg=new int[320*480]; // do I need to do Array.fill?
frame=0;
....
param.setPreviewSize(320,480);
....
camera.setPreviewCallbackWithBuffer(onPreviewFrame);
camera.startPreview();
}
public void onPreviewFrame(byte[] data, Camera camera) {
// extract the red channel from RGB565
for(int i=0;i<data.length;i+=2){
byte red=(byte) ((data[i] >> 3 ) & 0x1F); // RRRRRGGG |
GGGBBBBB
avg[i>>1]+=red;
}
ByteBuffer byteBuf = ByteBuffer.allocate(2 * data.length);
//data.length is 2*320*480
IntBuffer intBuf = byteBuf.asIntBuffer();
intBuf.put(avg);
FileOutputStream out = new FileOutputStream(
"/sdcard/nirs_avg_"+Integer.toString(frame)+".raw");
out.write(byteBuf.array());
out.flush();
out.close();
frame++;
}
}
if I plot the data, converted to a 2D image in matlab, the
images look like wrapped phase maps, with large numbers
around 10^8 ~ 10^9.
I am not familiar with Java. Can someone please give me a
hint which part of my code is wrong? I really appreciate
your input.
thank you in advance.
Qianqian
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