diff --git a/app/camera/camera.c b/app/camera/camera.c
index 39a8a91..b268273 100644
--- a/app/camera/camera.c
+++ b/app/camera/camera.c
@@ -4,15 +4,23 @@
 #include "FreeRTOS.h"
 #include "task.h"
 
+#define _CAM_REG_NULL 0xFFFF
+#define _CAM_REG_DELAY 0x0000
+#define CAMERA_SETTLE_MS 10
+#define CAMERA_FRAME_TIMEOUT 100
+
+struct camera_regval {
+  uint16_t addr;
+  uint8_t val;
+};
+
 #if _CAM_MODEL == SC031GS
 #include "sc031gs.h"
 #else
 #error _CAM_MODEL must be defined
 #endif
-APP_NOCACHE(uint8_t g_camera_fb[CAMERA_FB_COUNT][CAMERA_FB_SIZE], CAMERA_BUFFER_ALIGN);
 
-#define CAMERA_SETTLE_MS 10
-#define CAMERA_FRAME_TIMEOUT 100
+APP_NOCACHE(uint8_t g_camera_fb[CAMERA_FB_COUNT][CAMERA_FB_SIZE], CAMERA_BUFFER_ALIGN);
 
 hal_err_t _camera_reset() {
   hal_gpio_set(GPIO_CAMERA_PWR, GPIO_SET);
@@ -36,19 +44,19 @@ hal_err_t _camera_load_reg(uint16_t addr, uint8_t val) {
   return hal_i2c_send(I2C_CAMERA, _CAM_I2C_ADDR, buf, 3);
 }
 
-hal_err_t _camera_load_regs() {
+hal_err_t _camera_load_regs(const struct camera_regval regs[]) {
   size_t i = 0;
   hal_err_t err = HAL_SUCCESS;
 
   while(1) {
-    switch(camera_regs[i].addr) {
+    switch(regs[i].addr) {
       case _CAM_REG_DELAY:
-        vTaskDelay(pdMS_TO_TICKS(camera_regs[i].val));
+        vTaskDelay(pdMS_TO_TICKS(regs[i].val));
         break;
       case _CAM_REG_NULL:
         goto finish;
       default:
-        err = _camera_load_reg(camera_regs[i].addr, camera_regs[i].val);
+        err = _camera_load_reg(regs[i].addr, regs[i].val);
         if (err != HAL_SUCCESS) {
           goto finish;
         }
@@ -73,7 +81,7 @@ hal_err_t camera_start() {
     return err;
   }
 
-  if ((err = _camera_load_regs()) != HAL_SUCCESS) {
+  if ((err = _camera_load_regs(camera_regs)) != HAL_SUCCESS) {
     return err;
   }
 
@@ -100,3 +108,21 @@ hal_err_t camera_next_frame(uint8_t** frame) {
 hal_err_t camera_submit(uint8_t* frame) {
   return hal_camera_submit(frame);
 }
+
+hal_err_t camera_set_exposure(camera_exposure_t exposure) {
+  struct camera_regval regs[3];
+  _camera_exposure_regs(regs, exposure);
+  return _camera_load_regs(regs);
+}
+
+hal_err_t camera_set_analog_gain(uint8_t gain) {
+  struct camera_regval regs[3];
+  _camera_analog_gain_regs(regs, gain);
+  return _camera_load_regs(regs);
+}
+
+hal_err_t camera_set_digital_gain(uint8_t gain) {
+  struct camera_regval regs[3];
+  _camera_digital_gain_regs(regs, gain);
+  return _camera_load_regs(regs);
+}
diff --git a/app/camera/camera.h b/app/camera/camera.h
index 110ccaf..4acf2b3 100644
--- a/app/camera/camera.h
+++ b/app/camera/camera.h
@@ -3,14 +3,17 @@
 
 #include "hal.h"
 
-#define _CAM_REG_NULL 0xFFFF
-#define _CAM_REG_DELAY 0X0000
 #define _CAM_MODEL SC031GS
+#define CAMERA_MAX_ANALOG_GAIN 16
+#define CAMERA_MAX_DIGITAL_GAIN 8
 
-struct camera_regval {
-  uint16_t addr;
-  uint8_t val;
-};
+typedef enum {
+  EXPOSURE_500,
+  EXPOSURE_400,
+  EXPOSURE_300,
+  EXPOSURE_250,
+  EXPOSURE_125,
+} camera_exposure_t;
 
 hal_err_t camera_start();
 hal_err_t camera_stop();
@@ -18,4 +21,8 @@ hal_err_t camera_stop();
 hal_err_t camera_next_frame(uint8_t** frame);
 hal_err_t camera_submit(uint8_t* frame);
 
+hal_err_t camera_set_exposure(camera_exposure_t exposure);
+hal_err_t camera_set_analog_gain(uint8_t gain);
+hal_err_t camera_set_digital_gain(uint8_t gain);
+
 #endif /* __CAMERA_H__ */
diff --git a/app/camera/sc031gs.h b/app/camera/sc031gs.h
index 580752f..4a5ef58 100644
--- a/app/camera/sc031gs.h
+++ b/app/camera/sc031gs.h
@@ -54,7 +54,7 @@
 
 static const struct camera_regval camera_regs[] = {
   {0x0103, 0x01}, // soft reset.
-  {_CAM_REG_DELAY, 10}, // delay.
+  {_CAM_REG_DELAY, 10},
   {0x0100,0x00},
   {0x300f,0x0f},
   {0x3018,0x1f},
@@ -125,12 +125,12 @@ static const struct camera_regval camera_regs[] = {
   {0x3908,0x91},
   {0x3d08,0x01},
   SC031GS_GAIN_CFG_TABLE,
-  {SC031GS_EXPOSURE_H_REG,0x0f},
-  {SC031GS_EXPOSURE_L_REG,0xa0},
-  {SC031GS_GAIN_ANALOG_H_REG,0x07},
-  {SC031GS_GAIN_ANALOG_L_REG,0x1f},
-  {SC031GS_GAIN_DIGITAL_H_REG,0x03},
-  {SC031GS_GAIN_DIGITAL_L_REG,0x80},
+  {SC031GS_EXPOSURE_H_REG,0x0e},
+  {SC031GS_EXPOSURE_L_REG,0x13},
+  {SC031GS_GAIN_ANALOG_H_REG,0x01},
+  {SC031GS_GAIN_ANALOG_L_REG,0x10},
+  {SC031GS_GAIN_DIGITAL_H_REG,0x01},
+  {SC031GS_GAIN_DIGITAL_L_REG,0x10},
   {0x4500,0x59},
   {0x4501,0xc4},
   {0x5011,0x00},
@@ -143,6 +143,47 @@ static const struct camera_regval camera_regs[] = {
   {0x3317,0x0f},
   {_CAM_REG_NULL, 0x00},
 };
+
+const uint16_t _camera_exposure_table[] = {
+    0x0e13, 0x1198, 0x1776, 0x1c27, 0x384e
+};
+
+const uint16_t _camera_analog_gain_table[] = {
+    0x0010, 0x0110, 0x0118, 0x0310, 0x0314, 0x0318, 0x031c, 0x0710,
+    0x0712, 0x0714, 0x0716, 0x0718, 0x071a, 0x071c, 0x071e, 0x071f
+};
+
+const uint16_t _camera_digital_gain_table[] = {
+    0x0080, 0x0180, 0x01c0, 0x0380, 0x03a0, 0x03c0, 0x03e0, 0x03f8,
+};
+
+static inline void _camera_exposure_regs(struct camera_regval regs[3], camera_exposure_t exposure) {
+  uint16_t val = _camera_exposure_table[exposure];
+  regs[0].addr = SC031GS_EXPOSURE_H_REG;
+  regs[0].val = val >> 8;
+  regs[1].addr = SC031GS_EXPOSURE_L_REG;
+  regs[1].val = val & 0xff;
+  regs[2].addr = _CAM_REG_NULL;
+}
+
+static inline void _camera_analog_gain_regs(struct camera_regval regs[3], uint8_t gain) {
+  uint16_t val = _camera_analog_gain_table[gain - 1];
+  regs[0].addr = SC031GS_GAIN_ANALOG_H_REG;
+  regs[0].val = val >> 8;
+  regs[1].addr = SC031GS_GAIN_ANALOG_L_REG;
+  regs[1].val = val & 0xff;
+  regs[2].addr = _CAM_REG_NULL;
+}
+
+static inline void _camera_digital_gain_regs(struct camera_regval regs[3], uint8_t gain) {
+  uint16_t val = _camera_digital_gain_table[gain - 1];
+  regs[0].addr = SC031GS_GAIN_DIGITAL_H_REG;
+  regs[0].val = val >> 8;
+  regs[1].addr = SC031GS_GAIN_DIGITAL_L_REG;
+  regs[1].val = val & 0xff;
+  regs[2].addr = _CAM_REG_NULL;
+}
+
 #else
 #error This file must be only imported once.
 #endif
diff --git a/app/qrcode/qrcode.c b/app/qrcode/qrcode.c
index 0628b74..bc05a7c 100644
--- a/app/qrcode/qrcode.c
+++ b/app/qrcode/qrcode.c
@@ -838,16 +838,7 @@ void quirc_threshold(struct quirc *q)
     quirc_pixel_t *row = q->pixels;
     int width = q->w;
 
-    /*
-     * Ensure a sane, non-zero value for threshold_s.
-     *
-     * threshold_s can be zero if the image width is small. We need to avoid
-     * SIGFPE as it will be used as divisor.
-     */
-    if (threshold_s < THRESHOLD_S_MIN)
-        threshold_s = THRESHOLD_S_MIN;
-
-    fracmul = (32768 * (threshold_s - 1)) / threshold_s; // to use multipy instead of divide (not too many bits or we'll overflow)
+    fracmul = (32768 * (threshold_s - 1)) / threshold_s; // to use multiply instead of divide (not too many bits or we'll overflow)
     // to get the effect used below (a fraction of threshold_s-1/threshold_s
     // The second constant is to reduce the averaged values to compare with the current pixel
     fracmul2 = (0x100000 * (100 - THRESHOLD_T)) / (200 * threshold_s); // use as many bits as possible without overflowing
diff --git a/app/qrcode/qrscan.c b/app/qrcode/qrscan.c
index d2de133..8ccdbac 100644
--- a/app/qrcode/qrscan.c
+++ b/app/qrcode/qrscan.c
@@ -83,6 +83,14 @@ app_err_t qrscan_scan() {
   uint16_t score = QR_SCORE_RED;
   uint16_t prev_color = 0;
 
+  camera_exposure_t exposure = EXPOSURE_500;
+  uint8_t again = 1;
+  uint8_t dgain = 1;
+
+  camera_set_exposure(exposure);
+  camera_set_analog_gain(again);
+  camera_set_digital_gain(dgain);
+
   while (1) {
     if (camera_next_frame(&fb) != HAL_SUCCESS) {
       continue;
@@ -138,9 +146,46 @@ app_err_t qrscan_scan() {
 
     keypad_key_t k = ui_wait_keypress(0);
 
-    if ((k == KEYPAD_KEY_CANCEL) || (k == KEYPAD_KEY_BACK)) {
-      res = ERR_CANCEL;
-      goto end;
+    if (k != KEYPAD_KEY_INVALID) {
+      switch(k) {
+      case KEYPAD_KEY_1:
+        if (exposure < EXPOSURE_125) {
+          camera_set_exposure(++exposure);
+        }
+        break;
+      case KEYPAD_KEY_7:
+        if (exposure > EXPOSURE_500) {
+          camera_set_exposure(--exposure);
+        }
+        break;
+      case KEYPAD_KEY_2:
+        if (again < CAMERA_MAX_ANALOG_GAIN) {
+          camera_set_analog_gain(++again);
+        }
+        break;
+      case KEYPAD_KEY_8:
+        if (again > 1) {
+          camera_set_analog_gain(--again);
+        }
+        break;
+      case KEYPAD_KEY_3:
+        if (again < CAMERA_MAX_DIGITAL_GAIN) {
+          camera_set_digital_gain(++dgain);
+        }
+        break;
+      case KEYPAD_KEY_9:
+        if (dgain > 1) {
+          camera_set_digital_gain(--dgain);
+        }
+        break;
+      case KEYPAD_KEY_CANCEL:
+      case KEYPAD_KEY_BACK:
+        res = ERR_CANCEL;
+        goto end;
+        break;
+      default:
+        break;
+      }
     }
   }