Knowledge Base

Camera Settings in EthoVision

This functionality is available since EthoVision XT v15+ via the Noldus Basler Pylon Interface that EthoVision XT installs. However, Noldus Support recommends that these settings be made in Pylon Viewer (see Section H). The reason being when set/saved in Pylon Viewer, these same settings are applied to all of your EthoVision XT experiments. Should you want to change the settings for a one off experiment in EthoVision XT, here is how:

Aim: To adjust the settings of your camera within EthoVision XT. For example, the video resolution, the frame rate, or the exposure.

Important: To improve the quality of the image, always try adjusting the lighting and camera aperture before changing the settings in EthoVision XT.

To Access These Options

1. Choose Setup > Experiment Settings, and click the camera button for the camera you require.
2. Open the tab you require.

Format Tab

The Format tab is only available for the first camera. The settings you specify here are also applied to the other cameras.

You can change Resolution and Frame rate in EthoVision XT, but the new values are not kept in the camera software after restarting the computer. However, they are still selected in EthoVision XT.

Important: If you change resolution, open the Arena Settings and update the background image. If the Arena Settings are locked, delete all trials (if that is possible) or make a duplicate of the Arena Settings and there update the background image.

Resolution

For single arenas and subjects more than a couple of centimeters long, a resolution of 384x288 (PAL) or 320x240 (NTSC) is sufficient. The higher the resolution, the more accurate your tracking. However, when you choose to save video to a digital video file and record for a long time, the files can become quite large. The higher the video resolution, the bigger the files. If disk space is limiting, use the above-mentioned resolution.

Note: For analog cameras, the resolution is determined by the TV standard (see below). For some cameras there is only one video resolution available.

Frame Rate

This is the number of video images per second that are generated by the camera. For analog cameras, this is determined by the TV standard of your camera. For digital cameras, it can vary. A high frame rate is recommended when working with fast-moving animals, or when you want to detect movements like startle responses in fish or rapid turns in flying insects. High frame rates require more processing power. If you select a high frame rate, in some cases you need to lower the video resolution. This window shows a message when that is the case.

Note: The frame rate is not the same as the Sample rate.

Color Space

Color space determines how the information about brightness and color is encoded in the video frames that are sent to EthoVision XT. Note that this may impact the maximal framerate. The optimal color space differs between cameras.

• For monochrome cameras: Choose Y800. Check the preview image to assess whether the image quality is good.
• For color cameras: If the image is black-and-white instead of color and a Moire pattern appears in the image, try using another color space. Normally, the default color space gives a good image quality. Otherwise, use YUY2. If you use a high frame rate or resolution, this reduces the number of animals you can track simultaneously. This also depends on how fast your computer is.

Tip: In the Detection Settings, in the Detection Performance pane check the value under Missed Samples to get an indication of the quality of tracking.

Standard

This is only available for analog cameras. Select the TV standard of your camera. You can find this in the specifications section of your equipment's manual. It will probably be the standard used in your country.

• PAL: In Western Europe, China, Indonesia and Australia.
• NTSC: In United States, Canada and Japan.

Image Tab

Brightness, Contrast and Saturation are only available for analog cameras. Move the slider, click the arrows or change the number in one of the fields to adjust the settings and check the resulting image. Click the Default button to revert the Image settings to default. The settings on the other tabs will not change. Click the More Settings button to open a window with additional settings.

Brightness

Be aware that a too dark or too bright image may reduce the quality of video tracking. Brightness is not the same as Exposure; the latter is the period of time when the camera sensor is exposed to light.

Contrast

This is the difference in brightness or color that makes objects in an image distinguishable. Use this slider to enhance or reduce the contrast in the image.

Saturation

This is the strength or purity of the color and represents the amount of gray in proportion to the hue. A saturated color is pure, while an unsaturated color has a large percentage of gray.

Camera/General Tab

Some options are only available for Basler cameras.

Center Image

When selected, this option ensures that the image is centered over the sensor when not capturing the largest possible image. We recommend keeping this option selected.

If you want to have the camera image off center, for example to exclude part of the camera view, click the More button. This opens the Pylon Viewer software. First click Cancel in the EthoVision XT Video Settings window, then in Pylon Viewer double-click the camera name and under Features locate AOI Controls. For details, see the Basler camera documentation.

Binning

When selected, sensor pixels are grouped together to make one image pixel. For example, selecting 2 means two horizontal and two vertical pixels, thus 4 sensor pixels make up one image pixel. This increases the sensitivity of the camera but reduces the image resolution.

Exposure Time

Exposure determines the time when the sensor is exposed to light. The higher the value, the brighter the image. Note that if Exposure is too high, the camera may not be able to send the images at the supposed frame rate. In that case, the window shows that the frame rate is too low. Reduce the Exposure, or reduce the frame rate to have longer time intervals between subsequent video frames.

• For Zebrafish larvae: Enter 4000 or 2000, depending on the video resolution chosen.
• For rodents: A value below 20000 is fine.
• For a mosquito filmed under infrared: A value around 10000 is fine.
• All else being equal, faster animals require shorter exposure times.

Tip: If the image becomes too dark due to the short exposure time, increase the Gain.

Gain

Adjust the Gain to change the amplification level of the signal coming from the camera sensor. A higher value means more sensitivity. Increase the gain to make the picture brighter, for example in dark environments. Be aware that higher Gain may increase noise in the image.

Source: EthoVision XT 18 - GigE Install and Setup, Noldus Information Technology