# Construct View

1. Define the 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. by adjusting the red dashed rectangle over the image.

2. Once you finalize the ROI, the View is outlined in green.

## Using Views In a Tool Chain

You can generate multiple Views based on tool ROIs from a single image file. Views have an associated index that serves as a unique identifier for each View. A tool can also generate multiple Views, which subsequent tools in the tool chain can use as ROI input based on the View index.

For example, if you have a Red Analyze tool configured, you can use the defect regions in the Red Analyze tool output as Views for a subsequent Green Classify tool in the tool chain using the Extract Regions as Individual ROIs 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)., as follows:

1. Create a tool chain consisting of a Red Analyze tool and a Green Classify tool.

2. Configure the Red Analyze tool to identify defective areas on the image.

3. When setting up the ROI for the Green Classify tool, click the Extract Regions as Individual ROIs button and use the target name you configured for the Red Analyze tool output regions.

4. Select the View you want to use as the ROI for the Green Classify tool.

   Note: The View Index column is hidden by default in the View Browser list mode. To show the View Index column, click the button in the top right, open Edit Column, enable the View Index checkbox, and click Apply.

## Views Without ROI

If a View does not have an ROI configured, the View index is -1, and a warning icon appears next to the file name. For example, if the Red Analyze tool in the previous example does not find any defects, the Green Classify tool cannot extract any ROIs from the Views produced by the Red Analyze tool, which means that those Views receive an index of -1.