camera may be replaced by image file input now

linescan.py

 #!/usr/bin/python3
 
+import sys
 import math
-from picamera.array import PiRGBArray
-from picamera import PiCamera
 import json
 import time
 import cv2
@@ -10,22 +9,19 @@ import numpy as np
 import os
 import jack
 
-# we are a Jack MIDI jack_client to send MIDI messages
-jack_client = jack.Client("Woodsound Scanner")
-midi_outport = jack_client.midi_midi_outports.register("output")
-midi_output_queue=[] # MIDI messages ready to send
-
-# Jack MIDI jack_client output callback - feeds MIDI messages to Jack on it's demand
-@jack_client.set_process_callback
-def process(frames):
-  midi_outport.clear_buffer()
-  while midi_output_queue:
-    midi_outport.write_midi_event(0,midi_output_queue.pop())
-jack_client.activate()
 
 # load the configuration
 conf = json.load(open('conf.json'))
 
+# use RasPiCam capture device, or dummy file if filename is given
+if len(sys.argv)>1:
+  img = cv2.imread(sys.argv[1])
+  img = cv2.resize(img,(640, 480))
+  rawCapture=None
+else:
+  # use Raspi Camera
+  from picamera.array import PiRGBArray
+  from picamera import PiCamera
   # initialize the camera and grab a reference to the raw camera capture
   camera = PiCamera()
   camera.resolution = tuple(conf["resolution"])
@@ -34,6 +30,20 @@ camera.exposure_mode='off'
   camera.shutter_speed=conf["shutter_milliseconds"]*1000
   rawCapture = PiRGBArray(camera, size=tuple(conf["resolution"]))
 
+
+# we are a Jack MIDI jack_client to send MIDI messages
+jack_client = jack.Client("Woodsound Scanner")
+midi_outport = jack_client.midi_outports.register("output")
+midi_output_queue=[] # MIDI messages ready to send
+
+# Jack MIDI jack_client output callback - feeds MIDI messages to Jack on it's demand
+@jack_client.set_process_callback
+def process(frames):
+  midi_outport.clear_buffer()
+  while midi_output_queue:
+    midi_outport.write_midi_event(0,midi_output_queue.pop())
+jack_client.activate()
+
 # allow the camera to warmup
 print("[INFO] warming up...")
 time.sleep(conf["camera_warmup_time"])
@@ -45,12 +55,20 @@ threshold=conf["threshold"]
 
 # capture frames from the camera
 # clahe=cv2.createCLAHE(clipLimit=conf["contrast_limit"])
-for f in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):
+while True:
 
-    frame = f.array
+    if not rawCapture is None:
+      # clear the stream in preparation for the next frame
+      rawCapture.truncate(0)
+      # capture frame
+      camera.capture(rawCapture, format="bgr", use_video_port=True)
+      frame = rawCapture.array
+    else:
+      frame = img
     
     # crop down to some rectangular bar used for processing
-    cropped_frame=frame[100:280,0:640]
+    # cropped_frame=frame[100:280,0:640]
+    cropped_frame=frame[0:480,0:640]
 
     # crop single line for color histogram output
     line_frame=cropped_frame[140:141,5:635]
@@ -82,7 +100,5 @@ for f in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True
     if key == ord("q"):
             break
 
-    # clear the stream in preparation for the next frame
-    rawCapture.truncate(0)