Vignetting Correction (pylon Viewer)
The Vignetting Correction feature in the pylon Viewer
allows you to remove vignetting artifacts with a single click.
The Vignetting Correction feature
is available on selected ace U and ace L models (GigE and USB 3.0).
How It Works
Vignetting means a darkening of the corners of an image compared to
its center. It is a common effect in digital imaging and occurs when the
pixels at the edges of the sensor don't receive sufficient light. This
can happen, e.g., because the image circle is too small in relation to
the size of the sensor or because the light rays don't hit the sensor
at right angles like they do at the center of the sensor. This means that
the pixels at the edges have lower gray values.
To remove these vignetting artifacts, the Vignetting Correction feature
uses an algorithm that calculates a multiplier to bring the lower-than-expected
gray values up to normal levels. The correction data is saved in the camera
and can also be downloaded to use it on a different camera. Use the File Access option in Camera
menu to do this.
For best results, disable all non-linear features, e.g.,
light source presets or gamma, before creating the correction data. Afterwards,
you can enable them again.
To perform vignetting correction:
- Open the camera
if you have not already done so.
- Place a white sheet of paper in the camera's field of view.
- Stop continuous image acquisition if it is currently enabled.
- Click Camera > Vignetting Correction.
The algorithm creates the correction data and captures an image with
the correction data applied.
Messages about the result will be displayed in the Message
Log pane. Among other information, this will give you an error
value. This is an indication of the degree of correction achieved. The
closer the error value is to zero, the more effective the vignetting correction
has been.
You can download vignetting correction data from a camera and upload
it to a different camera.
To download vignetting correction data:
- Perform vignetting correction as described above.
- On the camera that you have performed the vignetting correction
on, click Camera > File Access.
The camera must be open.
- In the Camera File Access dialog,
select Vignetting Correction in the
dropdown list.
- Click Download and specify the desired location.
- Enter a file name, including a file extension, e.g., .txt, and
close the dialog.
To upload vignetting correction data:
- On the camera on which you want to upload the correction data,
click Camera > File
Access.
The camera must be open.
- In the Camera File Access dialog,
select Vignetting Correction in the
dropdown list.
- Click Upload and navigate to the
location where you saved the correction data file.
- Select the file and click Upload.
To apply the correction data on another camera, execute the VignettingCorrectionLoad
command.
- You should only upload vignetting correction data on cameras
with identical specifications to the one on which you created
the vignetting correction data, e.g., the sensor size must be
the same.
- Bear in mind that there is a certain variance between individual
cameras and lenses, i.e., correction data created on one camera
may not completely remove vignetting artifacts on another camera.
- If the upload fails, the VignettingCorrectionMode
parameter in the Features pane will
be disabled. If this happens, create a new set of vignetting correction
data and repeat the procedure.