Implement identification for imaging devices

TODO

@@ -1,6 +1,5 @@
 LIBRARY
 =======
-identification
 test suite against NFIQ compliance set
 make library optionally asynchronous and maybe thread-safe
 nbis cleanups

libfprint/core.c

@@ -81,10 +81,6 @@
  *
  * \section identification Identification
  *
- * libfprint supports enrollment and verification as described above. Although
- * libfprint does not yet support identification (it is planned), it is worth
- * introducing the concept to give you a complete picture.
- *
  * Identification is the process of comparing a freshly scanned fingerprint
  * to a <em>collection</em> of previously enrolled fingerprints. For example,
  * imagine there are 100 people in an organisation, and they all have enrolled

libfprint/fp_internal.h

@@ -225,6 +225,8 @@ int fpi_img_to_print_data(struct fp_img_dev *imgdev, struct fp_img *img,
 	struct fp_print_data **ret);
 int fpi_img_compare_print_data(struct fp_print_data *enrolled_print,
 	struct fp_print_data *new_print);
+int fpi_img_compare_print_data_to_gallery(struct fp_print_data *print,
+	struct fp_print_data **gallery, int match_threshold, int *match_offset);
 
 #endif
 

libfprint/img.c

@@ -364,6 +364,25 @@ int fpi_img_compare_print_data(struct fp_print_data *enrolled_print,
 	return r;
 }
 
+int fpi_img_compare_print_data_to_gallery(struct fp_print_data *print,
+	struct fp_print_data **gallery, int match_threshold, int *match_offset)
+{
+	struct xyt_struct *pstruct = (struct xyt_struct *) print->data;
+	struct fp_print_data *gallery_print;
+	int probe_len = bozorth_probe_init(pstruct);
+	size_t i = 0;
+
+	while (gallery_print = gallery[i++]) {
+		struct xyt_struct *gstruct = (struct xyt_struct *) gallery_print->data;
+		int r = bozorth_to_gallery(probe_len, pstruct, gstruct);
+		if (r >= match_threshold) {
+			*match_offset = i - 1;
+			return FP_VERIFY_MATCH;
+		}
+	}
+	return FP_VERIFY_NO_MATCH;
+}
+
 /** \ingroup img
  * Get a binarized form of a standardized scanned image. This is where the
  * fingerprint image has been "enhanced" and is a set of pure black ridges

libfprint/imgdev.c

@@ -305,6 +305,46 @@ static int img_dev_verify(struct fp_dev *dev,
 		return FP_VERIFY_NO_MATCH;
 }
 
+static int img_dev_identify(struct fp_dev *dev,
+	struct fp_print_data **print_gallery, size_t *match_offset,
+	struct fp_img **_img)
+{
+	struct fp_img_dev *imgdev = dev->priv;
+	struct fp_img_driver *imgdrv = fpi_driver_to_img_driver(dev->drv);
+	struct fp_img *img = NULL;
+	struct fp_print_data *print;
+	int match_score = imgdrv->bz3_threshold;
+	int r;
+
+	r = fpi_imgdev_capture(imgdev, 0, &img);
+
+	/* If we got an image, standardize it and return it even if the scan
+	 * quality was too low for processing. */
+	if (img)
+		fp_img_standardize(img);
+	if (_img)
+		*_img = img;
+	if (r)
+		return r;
+
+	r = fpi_img_to_print_data(imgdev, img, &print);
+	if (r < 0)
+		return r;
+	if (img->minutiae->num < MIN_ACCEPTABLE_MINUTIAE) {
+		fp_dbg("not enough minutiae, %d/%d", r, MIN_ACCEPTABLE_MINUTIAE);
+		fp_print_data_free(print);
+		return FP_VERIFY_RETRY;
+	}
+
+	if (match_score == 0)
+		match_score = BOZORTH3_DEFAULT_THRESHOLD;
+
+	r = fpi_img_compare_print_data_to_gallery(print, print_gallery,
+		match_score, match_offset);
+	fp_print_data_free(print);
+	return r;
+}
+
 void fpi_img_driver_setup(struct fp_img_driver *idriver)
 {
 	idriver->driver.type = DRIVER_IMAGING;
@@ -312,5 +352,6 @@ void fpi_img_driver_setup(struct fp_img_driver *idriver)
 	idriver->driver.exit = img_dev_exit;
 	idriver->driver.enroll = img_dev_enroll;
 	idriver->driver.verify = img_dev_verify;
+	idriver->driver.identify = img_dev_identify;
 }