I am using the example code sensor_exposure_control.py
# Sensor Exposure Control # # This example shows off how to control the camera sensor's # exposure manually versus letting auto exposure control run. # What's the difference between gain and exposure control? # # Well, by increasing the exposure time for the image you're getting more # light on the camera. This gives you the best signal to noise ratio. You # in general always want to increase the expsoure time... except, when you # increase the exposure time you decrease the maximum possible frame rate # and if anything moves in the image it will start to blur more with a # higher exposure time. Gain control allows you to increase the output per # pixel using analog and digital multipliers... however, it also amplifies # noise. So, it's best to let the exposure increase as much as possible # and then use gain control to make up any remaining ground. import sensor, image, time # Change this value to adjust the exposure. Try 10.0/0.1/etc. EXPOSURE_TIME_SCALE = 1.0 sensor.reset() # Reset and initialize the sensor. sensor.set_pixformat(sensor.GRAYSCALE) # Set pixel format to RGB565 (or GRAYSCALE) sensor.set_framesize(sensor.QVGA) # Set frame size to QVGA (320x240) # Print out the initial exposure time for comparison. print("Initial exposure == %d" % sensor.get_exposure_us()) sensor.skip_frames(time = 2000) # Wait for settings take effect. clock = time.clock() # Create a clock object to track the FPS. # You have to turn automatic gain control and automatic white blance off # otherwise they will change the image gains to undo any exposure settings # that you put in place... sensor.set_auto_gain(False) sensor.set_auto_whitebal(False) # Need to let the above settings get in... sensor.skip_frames(time = 500) current_exposure_time_in_microseconds = sensor.get_exposure_us() print("Current Exposure == %d" % current_exposure_time_in_microseconds) # Auto exposure control (AEC) is enabled by default. Calling the below function # disables sensor auto exposure control. The additionally "exposure_us" # argument then overrides the auto exposure value after AEC is disabled. sensor.set_auto_exposure(False, \ exposure_us = int(current_exposure_time_in_microseconds * EXPOSURE_TIME_SCALE)) print("New exposure == %d" % sensor.get_exposure_us()) # sensor.get_exposure_us() returns the exact camera sensor exposure time # in microseconds. However, this may be a different number than what was # commanded because the sensor code converts the exposure time in microseconds # to a row/pixel/clock time which doesn't perfectly match with microseconds... # If you want to turn auto exposure back on do: sensor.set_auto_exposure(True) # Note that the camera sensor will then change the exposure time as it likes. # Doing: sensor.set_auto_exposure(False) # Just disables the exposure value update but does not change the exposure # value the camera sensor determined was good. while(True): clock.tick() # Update the FPS clock. img = sensor.snapshot() # Take a picture and return the image. print(clock.fps()) # Note: OpenMV Cam runs about half as fast when connected # to the IDE. The FPS should increase once disconnected.
I have two different sensors, the Global Shutter Camera and an IR Sensor.
I want to measure the exposure time and the frames per second (FPS). As can be seen in the Terminal, I have the following results:
Exposure = 17031
FPS = 33.33333
Exposure = 805325451
FPS = 8.403361
Here there is a difference between both sensors and it makes the IR Sensor seems wrong.
Do you know why and what is the problem?