73 lines
2.6 KiB
Python
73 lines
2.6 KiB
Python
from __future__ import print_function
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import picamera
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from picamera import mmal, mmalobj, exc
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from picamera.mmalobj import to_rational
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import time
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MMAL_PARAMETER_ANALOG_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x59
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MMAL_PARAMETER_DIGITAL_GAIN = mmal.MMAL_PARAMETER_GROUP_CAMERA + 0x5A
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def set_gain(camera, gain, value):
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"""Set the analog gain of a PiCamera.
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camera: the picamera.PiCamera() instance you are configuring
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gain: either MMAL_PARAMETER_ANALOG_GAIN or MMAL_PARAMETER_DIGITAL_GAIN
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value: a numeric value that can be converted to a rational number.
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"""
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if gain not in [MMAL_PARAMETER_ANALOG_GAIN, MMAL_PARAMETER_DIGITAL_GAIN]:
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raise ValueError("The gain parameter was not valid")
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ret = mmal.mmal_port_parameter_set_rational(camera._camera.control._port,
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gain,
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to_rational(value))
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if ret == 4:
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raise exc.PiCameraMMALError(ret, "Are you running the latest version of the userland libraries? Gain setting was introduced in late 2017.")
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elif ret != 0:
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raise exc.PiCameraMMALError(ret)
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def set_analog_gain(camera, value):
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"""Set the gain of a PiCamera object to a given value."""
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set_gain(camera, MMAL_PARAMETER_ANALOG_GAIN, value)
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def set_digital_gain(camera, value):
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"""Set the digital gain of a PiCamera object to a given value."""
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set_gain(camera, MMAL_PARAMETER_DIGITAL_GAIN, value)
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if __name__ == "__main__":
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with picamera.PiCamera() as cam:
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cam.start_preview(fullscreen=False, window=(0,50,640,480))
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time.sleep(2)
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# fix the auto white balance gains at their current values
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g = cam.awb_gains
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cam.awb_mode = "off"
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cam.awb_gains = g
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# fix the shutter speed
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cam.shutter_speed = cam.exposure_speed
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print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))
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print("Attempting to set analogue gain to 1")
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set_analog_gain(cam, 1)
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print("Attempting to set digital gain to 1")
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set_digital_gain(cam, 1)
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# The old code is left in here in case it is a useful example...
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#ret = mmal.mmal_port_parameter_set_rational(cam._camera.control._port,
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# MMAL_PARAMETER_DIGITAL_GAIN,
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# to_rational(1))
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#print("Return code: {}".format(ret))
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try:
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while True:
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print("Current a/d gains: {}, {}".format(cam.analog_gain, cam.digital_gain))
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time.sleep(1)
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except KeyboardInterrupt:
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print("Stopping...")
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