This article will explain how each of the image adjustment settings in the Web UI will ultimately affect the image that the DNNCam produces. Having a clear and well adjusted image can help with detection and improve the accuracy of the AI applications running on the device.
The following image settings can be adjusted using the Web UI:
- Auto White Balance Mode
- Denoise Mode and Strength
- Framerate (Web UI v2 only)
- Exposure Min/Max
- Gain Min/Max
- Iris (this is a Lens setting, but affects the image)
Auto White Balance (AWB)
White balance is the process of removing unrealistic color casts, so that an object that is white appears white when processed by the camera. Camera white balance has to take into account the "color temperature" of a light source, which refers to the relative warmth/coolness of white light (see this article on White Balance).
There are a variety of AWB modes available in the DNNCam configuration:
- Auto - If you're unsure, use this option. The device will automatically try to remove unrealistic color, but this doesn't always perform perfectly.
- Off - No auto white balance will be applied to the image.
- Incandescent - If there is lighting using incandescent light bulbs, this option should work well to remove the warm, yellow to orange look of the image coming off of the camera.
- Fluorescent - This is useful under fluorescent light when the AWB doesn't remove the blue or green cast completely.
- Daylight - This is useful for common daylight conditions where there is a minimal amount of shaded areas in the image.
- Twilight - Twilight conditions generally present an orange tone with low color temperature, so using twilight AWB mode will make the colors look better in twilight scenarios.
- Shade - Shaded areas, or overcast days, usually present lower color tones, so the shade AWB mode will warm up the color tone.
Denoise
The Web UI allows you to configure the denoise mode to one of three options (Fast, Off, or High Quality) and allows you to set the denoise strength on a scale of 1-10. Denoise removes the amount of noise seen in the video, and the configuration choices made here should be dependent on the amount of noise seen in the Live View video on screen.
'Fast' mode is recommended, so try with this and adjusting strength to fit your needs. If this doesn't seem to work and there's still some noise in your image, try adjusting to 'High Quality' and adjust the strength until you're happy with how the Live View feed looks.
If you would like to turn off denoise, use the 'Off' mode.
Framerate (Web UI v2 only)
Adjusting the framerate will change how often images are pulled from the image sensor. It's recommended to keep the framerate on 'Auto', but it can sometimes be useful to turn down the framerate and increase the exposure for low-light scenarios. The maximum framerate is 60 frames per second.
Please note that the auto framerate will change as necessary to match the max exposure setting that is configured.
Exposure Min/Max
Exposure is the amount of light which reaches the camera sensor. A correctly exposed image has detail in both the darkest and the brightest parts of the frame, where as overexposure means there is too much light in the lights parts, and underexposure means that there's too little lights in the darkest parts of the frame.
The minimum and maximum values configurable using the Web UI are referring to the shutter speed, meaning how long the sensor is exposed to light. Fast shutter speeds will often present darker images with less blur, while slow shutter speeds will be much brighter but may have blurring depending on how quickly objects in the object are moving. This is a great article regarding exposure from IPVM.
If you are struggling with low-light scenarios, it may be helpful to adjust the min and max values to a greater value to allow for slower shutter speeds, but be conscious that this may result in some blurring.
Gain
The Web UI allows you to adjust the minimum and maximum Gain values, on a scale of 0-180. Higher levels of gain amplify the signal, resulting in greater levels of brightness and contrast. Lower levels of gain will darken the image, and soften the contrast. Effectively, the gain setting affects the sensitivity to light.
The gain should be adjusted when you're either seeing the image be too bright or too dim. However, it's important to find an effective medium (if you are adjusting the gain setting) in scenarios where the light source varies, as a gain setting that looks okay at one point in time can be ineffective at another time of the day.
Iris
The iris is a lens setting that physically adjusts how much light is being let onto the image sensor. This, in conjunction with the shutter speed set by the Exposure setting will affect the overall exposure of the image being seen by the device.
Increase the Iris percentage in the Web UI to allow more light onto the image sensor and decrease the Iris percentage value to decrease the amount of light being let through. A high iris value is generally better for lower-light scenarios, where a low value will be more beneficial for bright scenarios.
