### Adaptive Threshold

**Block Category:** Operations

Input Image
Format

**Input Image Requirements:** Gray scale

**Description:** The Adaptive Threshold block creates a
binary image by classifying each pixel as either dark or light based on whether
its intensity value is above or below the specified threshold.

**Constant: **Indicates a constant value subtracted from
the mean or weighted mean**. **Specify the constant as an integer.

**Matrix Dim:** Indicates the matrix size of the pixel
neighborhood used to calculate a threshold value for a pixel. Specify the size
as an odd integer greater than 1.

#### Method

*Gaussian*: Indicates
that the threshold value T(*x,y*) is a weighted sum (cross-correlation with
a Gaussian window) of the pixel neighborhood of (*x,y*) minus the specified
constant.

*Mean*: Indicates that the threshold value T(*x,y*) is the
mean of the pixel neighborhood of (*x,y*) minus the specified constant.

**Threshold: **Indicates the thresholding type. There
are two choices: **Binary** and **Binary Invert**.

#### Example

In this example, four binary images are created by varying
the algorithm, threshold, size, and constant values. In all but Output1 (bottom
display), the mean of neighborhood size of 35 x 35 is applied to the adaptive
threshold. In Output1, a smaller neighborhood size is used and results in a
blurrier image. Output 2 uses the Binary (rather than Binary Invert) threshold
type.