Question

What is flat-field correction?

Answer

Flat field correction is a technique that improves image quality by removing artifacts that are caused by variations in the pixel-to-pixel sensitivity of the camera (image sensor) and/or illuminator. Additionally, flat field correction can remove distortions in the optical path (including small dirt particles on the image sensor). It is a standard calibration procedure in contemporary digital cameras.

• For the overview camera, flat field correction uses the flat field image that is created when you recalibrate.
• For the objective camera, flat field correction uses the flat field image that is created when you recalibrate and when the uScope self-calibrates before each scan.

Flat field correction eliminates or reduces gradient effects of the illuminator and objective as well as optical distortions like dirt on the image sensor. It will not eliminate the effects of dirt or debris on the slide or cover slip.

The following two images illustrate the effects of flat-field correction.

Refer to uScope Navigator Filters or more information about image processing filters.

Note
The flat-field correction filter is available only for overview and slide camera filter sequences. It may be selected as the first filter in a sequence only.

Selecting the Overview Filter

The overview filter is applied to the overview image. It may be selected under Device Settings–Overview Camera. The Default Filter drop down lets you select from the available filters.

There are several filters that are included when you install uScope Navigator.

• FF includes the Flat-Field correction filter.
• FF-LUT includes Flat-Field correction and a conservative Look-Up Table that increases the brightness and contrast.

We recommend using the FF-LUT filter for the overview camera.

Selecting the Objective Filter

The objective filter is applied to images captured through the objective. It may be selected from the Device Settings or from the Browse window in Browse Mode.

Device Settings

Under Device Settings–10x/20x/40x/60x Camera, the Default Filter drop down lets you select from the available filters.

The FF filter includes flat-field correction only. This is the filter we recommend using for the objective camera.

Browse Mode Settings

In uScope Navigator v4.5 and later, you may select the objective filter while browsing as shown.