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Add image enhancement function for upek-sensors

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This commit is contained in:
Pascal Höhnel 2026-03-21 08:48:42 +01:00
parent 66b1ada0d6
commit e31ddff4e8
2 changed files with 58 additions and 1 deletions
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4
libfprint/drivers/upeksonly.c
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@ -1489,6 +1489,7 @@ fpi_device_upeksonly_class_init (FpiDeviceUpeksonlyClass *klass)
dev_class->type = FP_DEVICE_TYPE_USB;
dev_class->id_table = id_table;
dev_class->scan_type = FP_SCAN_TYPE_SWIPE;
dev_class->nr_enroll_stages = 10;
dev_class->usb_discover = dev_discover;
@ -1546,6 +1547,9 @@ dev_init (FpImageDevice *dev)
case UPEKSONLY_2016:
self->img_width = IMG_WIDTH_2016;
self->assembling_ctx.line_width = IMG_WIDTH_2016;
/* The sensor resolution is too low for the normal threshold. */
fpi_image_device_set_bz3_threshold (dev, 20);
break;
default:

55
libfprint/drivers/upektc_img.c
View file

@ -26,6 +26,54 @@
static void start_capture (FpImageDevice *dev);
static void start_deactivation (FpImageDevice *dev);
/* Enhance image for better minutiae detection on small swipe sensors.
* Applies contrast stretching and 2x nearest-neighbor upscale.
* Returns a new FpImage; caller is responsible for the original. */
static FpImage *
upektc_img_enhance (FpImage *orig)
{
guint w = orig->width;
guint h = orig->height;
guint new_w = w * 2;
guint new_h = h * 2;
guchar *src = orig->data;
FpImage *enhanced;
guchar *dst;
guint i, x, y;
/* Step 1: contrast stretch (histogram stretch to full 0-255 range) */
guchar min_val = 255, max_val = 0;
for (i = 0; i < w * h; i++)
{
if (src[i] < min_val)
min_val = src[i];
if (src[i] > max_val)
max_val = src[i];
}
if (max_val > min_val)
{
guint range = max_val - min_val;
for (i = 0; i < w * h; i++)
src[i] = (guchar) (((guint) (src[i] - min_val) * 255) / range);
}
/* Step 2: 2x nearest-neighbor upscale */
enhanced = fp_image_new (new_w, new_h);
enhanced->flags = orig->flags;
dst = enhanced->data;
for (y = 0; y < new_h; y++)
{
guint sy = y / 2;
for (x = 0; x < new_w; x++)
dst[y * new_w + x] = src[sy * w + x / 2];
}
return enhanced;
}
#define EP_IN (1 | FPI_USB_ENDPOINT_IN)
#define EP_OUT (2 | FPI_USB_ENDPOINT_OUT)
#define CTRL_TIMEOUT 4000
@ -335,9 +383,13 @@ capture_read_data_cb (FpiUsbTransfer *transfer, FpDevice *device,
fp_dbg ("Image size is %lu",
(gulong) self->image_size);
img = fp_image_new (img_class->img_width, img_class->img_height);
img->flags |= FPI_IMAGE_PARTIAL;
memcpy (img->data, self->image_bits,
self->image_size);
{
FpImage *enhanced = upektc_img_enhance (img);
g_object_unref (img);
img = enhanced;
}
fpi_image_device_image_captured (dev, img);
fpi_image_device_report_finger_status (dev,
FALSE);
@ -770,6 +822,7 @@ fpi_device_upektc_img_class_init (FpiDeviceUpektcImgClass *klass)
dev_class->type = FP_DEVICE_TYPE_USB;
dev_class->id_table = id_table;
dev_class->scan_type = FP_SCAN_TYPE_SWIPE;
dev_class->nr_enroll_stages = 10;
dev_class->usb_discover = discover;
img_class->img_open = dev_init;