A descriptor is a collection of camera feature properties that is applied to an image frame. Since each frame can have a unique descriptor, they can be used to change camera settings on a frame by frame basis. The "Descriptors" tab allows the user to add/modify/delete descriptors and view the resulting frame capture.
Note: For a list of cameras that support these descriptors shown in Capture OEM, please see Descriptors.
For information on the API Frame Descriptor, which contains the settings for a captured frame, please see Frame Descriptor
What it is:
A descriptor is a set of parameters associated with a frame that allows for rapid changes of camera parameters in a deterministic manner
The descriptor defines the value of each parameter
Each frame can have a unique descriptor, custom descriptors can be used to change camera settings on a frame-by-frame basis for each frame in the video stream
The camera will apply each descriptor in turn when capturing images and will output one frame per descriptor
After the last descriptor is used, the next frame in the stream will return to the first descriptor
When to use:
Descriptors are useful for obtaining different views of the same image.
Zooming in on several smaller regions of interest within a larger image
Panning to different ROI locations in the field of view
Obtaining images with different exposure times
Sequencing through various trigger inputs and General-Purpose outputs (GPOs) settings
How to use:
Descriptors can be programmed using Pixelink Capture OEM. Most features that can be controlled via Capture OEM can be modified in a descriptor. The exceptions are the gamma correction/look-up table feature and Flat Field Correction.
Select the Descriptors tab in the PxLDevApp
Select the Host Update mode
Click create to enable the first descriptor
In the Descriptor Focus
Select the button to the right of any of the camera control settings that are highlighted in bold
Modify the value in the dialog that pops up
Close the dialog
Note: Changing any of the camera settings on the normal tab panels will also change the setting for the current descriptor
Add / Remove Descriptors
Click on “Create”
You will see a new descriptor labelled “Descriptor # 1” in the tree view
Repeat this step for as many descriptors as desired. (ApiInvalidParameterError will be returned if you attempt to create more descriptors than the camera supports).
Click on the descriptor that you wish to modify in the tree view, labelled “Descriptor # N” (where N is the number of the descriptor you wish to modify)
Click on the feature controls from the feature list and set the desired settings for the descriptor.
Repeat these steps for all descriptors.
Click on “Play” to see a preview of the descriptors that have been created
Click on the descriptor that you wish to remove in the tree view, labelled “Descriptor # N” (where N is the number of the descriptor you wish to remove)
Click on “Delete”, the selected descriptor will be removed.
Or, to remove all descriptors at once, click on “Delete All”
Change a Descriptor without affecting Camera
To change a descriptors settings without affecting the image being displayed, click on the desired descriptor and then click on "Host"
Click on the feature controls that you wish to modify
To apply the "Host" descriptor settings, click on "Update Now" or click on "Camera
Note: It is recommended that all changes to preset descriptors be made in "Host Mode" and updated accordingly.
Descriptor in Focus
This entry indicates which descriptor is currently in focus.
“none” means that no descriptors have been created
N/A next to a "Descriptor in Focus" means that it is not available with the camera configuration in use
A number would suggest the descriptor number that is currently selected