DBFace using with Android tflite format

[Zeleni9]

Hello,

I have a question about using the db_keras.tflite model in Android. I am not sure the correct parameters for the face detector when generating anchors. If you can provide info about them that would be amazing. Info that I am lacking are feature sizes & anchor sizes with anchor ratios, here I have added some random data from another object detector:

private static final int[] feature_map_sizes = new int[] {33, 17, 9, 5, 3};

private static final float[][] anchor_sizes = new float[][] {{0.04f, 0.056f}, {0.08f, 0.11f}, {0.16f, 0.22f}, {0.32f, 0.45f}, {0.64f, 0.72f}};

private static final float[] anchor_ratios = new float[] {1.0f, 0.62f, 0.42f};`

If u have pre-processing and post-processing for face detector in Android Java code that would help immensely. Thank you.

[terryky]

I don't have any information about the db_keras.tflite you mentioned.
The pre-processing and post-processing depend on the tflite model, so please ask the person who designed that model.

[Zeleni9]

It is dbface model from your repository just didnt write full name dbface_keras_480x640_float32_nhwc.tflite DBFace Model

[terryky]

This model (dbface_keras_480x640_float32_nhwc.tflite) doesn't require anchors.
The detected region can be obtained directly from the inference output.
please refer the post processing code as below:

android_tflite/tflite_dbface/app/src/main/cpp/tflite_dbface.cpp

Lines 83 to 133 in 6a6d889

	decode_bounds (std::list<face_t> &face_list, float score_thresh)
	{
	face_t face_item;
	float *scores_ptr = (float *)s_detect_tensor_hm.ptr;
	int score_w = s_detect_tensor_hm.dims[2];
	int score_h = s_detect_tensor_hm.dims[1];
	for (int y = 0; y < score_h; y ++)
	{
	for (int x = 0; x < score_w; x ++)
	{
	int idx = y * score_w + x;
	float score = scores_ptr[idx];
	if (score < score_thresh)
	continue;
	float *p = get_bbox_ptr (idx);
	float bx = p[0];
	float by = p[1];
	float bw = p[2];
	float bh = p[3];
	fvec2 topleft, btmright;
	topleft.x = (x - bx) / (float)score_w;
	topleft.y = (y - by) / (float)score_h;
	btmright.x = (x + bw) / (float)score_w;
	btmright.y = (y + bh) / (float)score_h;
	face_item.score = score;
	face_item.topleft = topleft;
	face_item.btmright = btmright;
	/* landmark positions (5 keys) */
	float *lm = get_landmark_ptr (idx);
	for (int j = 0; j < kFaceKeyNum; j ++)
	{
	float lx = lm[j ] * 4;
	float ly = lm[j + 5] * 4;
	lx = (_exp (lx) + x) / (float)score_w;
	ly = (_exp (ly) + y) / (float)score_h;
	face_item.keys[j].x = lx;
	face_item.keys[j].y = ly;
	}
	face_list.push_back (face_item);
	}
	}
	return 0;
	}