Problem with exposure time and FPS

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:

Global Shutter
Exposure = 17031
FPS = 33.33333

IR Sensor
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?

Thank you!


Global Shutter.png

What’s the IR sensor?

If it’s the FLIR that doesn’t have exposure control. Those values you are seeing would just be garbage then.

We should disable the implementation of the stubs in the FLIR code so exposure control methods error out…

Yes, it’s the FLIR sensor.

Do you know if there is any way to control the sensor speed?

Thank you!

You can’t change it from 9 FPS. As an export controlled product it’s locked at that speed by FLIR.