rwb27 · April 27, 2023 15:09 · rwb27 · Dec 7, 2020 · vijayashri91 · Mar 6, 2021
diff --git a/set_picamera_gain.py b/set_picamera_gain.py
 from __future__ import print_function

 import picamera
 from picamera import mmal, mmalobj, exc
 from picamera.mmalobj import to_rational
 import time


 MMAL_PARAMETER_ANALOG_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x59
 MMAL_PARAMETER_DIGITAL_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x5A

 def set_gain(camera, gain, value):
    """Set the analog gain of a PiCamera.
    
    camera: the picamera.PiCamera() instance you are configuring
    gain: either MMAL_PARAMETER_ANALOG_GAIN or MMAL_PARAMETER_DIGITAL_GAIN
    value: a numeric value that can be converted to a rational number.
    """
    if gain not in [MMAL_PARAMETER_ANALOG_GAIN, MMAL_PARAMETER_DIGITAL_GAIN]:
        raise ValueError("The gain parameter was not valid")
    ret = mmal.mmal_port_parameter_set_rational(cam._camera.control._port, 
                                                    gain,
                                                    to_rational(value))
    if ret == 4:
        raise exc.PiCameraMMALError(ret, "Are you running the latest version of the userland libraries? Gain setting was introduced in late 2017.")
    elif ret != 0:
        raise exc.PiCameraMMALError(ret)

 def set_analog_gain(camera, value):
    """Set the gain of a PiCamera object to a given value."""
    set_gain(camera, MMAL_PARAMETER_ANALOG_GAIN, value)

 def set_digital_gain(camera, value):
    """Set the digital gain of a PiCamera object to a given value."""
    set_gain(camera, MMAL_PARAMETER_DIGITAL_GAIN, value)


 if __name__ == "__main__":
    with picamera.PiCamera() as cam:
        cam.start_preview(fullscreen=False, window=(0,50,640,480))
        time.sleep(2)

        # fix the auto white balance gains at their current values
        g = cam.awb_gains
        cam.awb_mode = "off"
        cam.awb_gains = g

        # fix the shutter speed
        cam.shutter_speed = cam.exposure_speed

        print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))

        print("Attempting to set analogue gain to 1")
        set_analog_gain(cam, 1)
        print("Attempting to set digital gain to 1")
        set_digital_gain(cam, 1)
        # The old code is left in here in case it is a useful example...
        #ret = mmal.mmal_port_parameter_set_rational(cam._camera.control._port, 
        #                                            MMAL_PARAMETER_DIGITAL_GAIN,
        #                                            to_rational(1))
        #print("Return code: {}".format(ret))

        try:
            while True:
                print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))
                time.sleep(1)
        except KeyboardInterrupt:
            print("Stopping...")


diff --git a/setting picamera gain.md b/setting picamera gain.md
	from __future__ import print_function

	import picamera
	from picamera import mmal, mmalobj, exc
	from picamera.mmalobj import to_rational
	import time


	MMAL_PARAMETER_ANALOG_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x59
	MMAL_PARAMETER_DIGITAL_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x5A

	def set_gain(camera, gain, value):
	"""Set the analog gain of a PiCamera.

	camera: the picamera.PiCamera() instance you are configuring
	gain: either MMAL_PARAMETER_ANALOG_GAIN or MMAL_PARAMETER_DIGITAL_GAIN
	value: a numeric value that can be converted to a rational number.
	"""
	if gain not in [MMAL_PARAMETER_ANALOG_GAIN, MMAL_PARAMETER_DIGITAL_GAIN]:
	raise ValueError("The gain parameter was not valid")
	ret = mmal.mmal_port_parameter_set_rational(cam._camera.control._port,
	gain,
	to_rational(value))
	if ret == 4:
	raise exc.PiCameraMMALError(ret, "Are you running the latest version of the userland libraries? Gain setting was introduced in late 2017.")
	elif ret != 0:
	raise exc.PiCameraMMALError(ret)

	def set_analog_gain(camera, value):
	"""Set the gain of a PiCamera object to a given value."""
	set_gain(camera, MMAL_PARAMETER_ANALOG_GAIN, value)

	def set_digital_gain(camera, value):
	"""Set the digital gain of a PiCamera object to a given value."""
	set_gain(camera, MMAL_PARAMETER_DIGITAL_GAIN, value)


	if __name__ == "__main__":
	with picamera.PiCamera() as cam:
	cam.start_preview(fullscreen=False, window=(0,50,640,480))
	time.sleep(2)

	# fix the auto white balance gains at their current values
	g = cam.awb_gains
	cam.awb_mode = "off"
	cam.awb_gains = g

	# fix the shutter speed
	cam.shutter_speed = cam.exposure_speed

	print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))

	print("Attempting to set analogue gain to 1")
	set_analog_gain(cam, 1)
	print("Attempting to set digital gain to 1")
	set_digital_gain(cam, 1)
	# The old code is left in here in case it is a useful example...
	#ret = mmal.mmal_port_parameter_set_rational(cam._camera.control._port,
	# MMAL_PARAMETER_DIGITAL_GAIN,
	# to_rational(1))
	#print("Return code: {}".format(ret))

	try:
	while True:
	print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))
	time.sleep(1)
	except KeyboardInterrupt:
	print("Stopping...")