# Filters

The VisionPro Deep Learning GUI provides several areas where you can use filter expression grammar to filter your data. These filters are available in various areas of the GUI. Some of them can also be used during runtime to filter results. The VisionPro Deep Learning filter grammar allows you to write expressions that evaluate to a Boolean, integer, or floating point value on a per view A view of an image is a region of pixels in an image. Tool processing is limited to the pixels within the view. You can manually specify a view, or you can use the results of an upstream tool to generate a view. basis.

The following table lists the areas in the VisionPro Deep Learning GUI where filters are available, and the context in which they are used:

GUI Location | Description | Runtime Setting
--- | --- | ---
View Browser - Display Filter and Sort Filter | Used to return specific views. The Display Filter only displays views that evaluate to True. These expressions must evaluate to a Boolean result. Pressing the Process button for the tool only processes the views that evaluate to True for the expression. The Sort Filter expressions must evaluate to an integer or a floating point value. You can order the views can be, ascending or descending, based on the value returned by the expression. | No
Edit ROI The Region of Interest (ROI) defines the area of operation for the tool. The ROI preserves the positions, angles, stretch and skew of the original image. | Following a Blue Locate tool: Either a feature A feature is a visually distinguishable area in an image. Features typically represent something of interest for the application (a defect, an object, a particular component of an object). or match filter expression, which is used to determine which feature types or model A specific spatial arrangement of a set of features (Blue Locate and Blue Read tools only.) During a post-processing step, the Blue Locate and Blue Read tools can fit all of the features detected in an image to the models defined for the tool. The overall pose and identity of the model is then returned. matches are used to generate the ROIs. Following a Green Classify tool: A view-level filter expression, which determines which views to process. | Yes
Region Filter | This filter is a processing tool parameter for the Red Analyze tool. You can use the filter to determine which regions you want the tool to return. Applying the region filter directly changes the result of Red Analyze tool. You can also reference view-level properties using the view. prefix. Only a handful of view properties, for example width and height, are available at runtime. For more information, see Region Filter. | Yes
Feature Filter | This filter is a processing tool parameter of the Blue Locate tool. You can use the filter to determine which features are returned by the tool, and in turn, output a downstream ROI for another Deep Learning tool. In addition, you can also reference view-level properties using the view. prefix. However, only a handful of view properties, for example width and height, are available at runtime. | Yes
Database Overview Filter (Expert Mode only) | You can use this filter on the result of the processing. This filter does not affect the result of processing, it only filters out the given processing results. But it can affect the results shown in the Database Overview statistics such as the Confusion Matrix, the Score Distribution Graph, and tables. The Database Overview filter supports all tools. |