# Brightness

The Brightness tool allows you to determine whether a feature is present or not present based on an average greyscale value, or brightness, of the pixels in the defined region.

The Brightness tool is useful when a feature of a good part is much darker or brighter than the feature on a bad part. Increases or decreases in the brightness of a feature are a good indication of the presence or absence of a part. For example, you can quickly verify the presence or absence of a light-colored bottle cap by measuring the brightness within the region.

To add the Brightness tool to your job:

1. Open the Inspect tool palette, expand the Presence/Absence tool group, and select the Brightness tool.

2. In the dialog, define the region by resizing and repositioning the box on the acquisition display screen. You can change the shape of the box using the Search Shape dropdown on the right. The available shapes are Rectangle, Circle, Annulus, and Polygon.

3. You can also add a subregion to your model region to mask out irrelevant or confusing features by right clicking on the acquisition display screen, and selecting Add Subregion > Shape in the dropdown menu that appears. By default, the subregion is added to the model region, but you can change it to subtract by right clicking on the acquisition screen, and selecting Subregion Operation > Subtract in the dropdown menu.

4. Click OK.

To adjust range limits:

Toggle the Normal/Inverted toggle to change the way the tool result is generated. If set to Normal, the tool produces a passing result if the brightness value falls between the defined minimum and maximum values. If set to Inverted, the tool produces a passing result if the brightness value falls outside the defined minimum and maximum values.

Adjust the valid range by changing the Minimum and Maximum greyscale values using the sliders or by providing the numerical values in the boxes below the slider. To help determine the optimal greyscale values, you can hover your cursor over a pixel in the acquisition display screen to see the Approximate Pixel Value in the bottom right corner of the acquisition display screen. The parentheses contain the coordinates of the pixel, and the greyscale value of the pixel is given after the = sign.

Click Set Min/Max to use automatically calculated minimum and maximum greyscale values. The automatically calculated minimum and maximum values are 10% below and above the mean greyscale value within the defined region when you add the tool or click the Set Min/Max button.

You can also enable advanced tool settings if your job requires more complex configuration. For more information on the advanced tool settings that are available, see Advanced Tool Settings.