2.6.1.1 imgAutoLevel

1 Menu Information
2 Brief Information
3 Command Line Usage
4 X-Function Execution Options
5 Variables
6 Description
7 Examples
8 Algorithm
9 References
10 Related X-Functions

Menu Information

Image: Adjustments: Auto Level

Brief Information

Apply auto leveling to image

Command Line Usage

1. imgAutoLevel auto:=intensity;

2. imgAutoLevel img:=[Mbook1]Msheet1!Mat(1) auto:=contrast oimg:=<new>;

X-Function Execution Options

Please refer to the page for additional option switches when accessing the x-function from script

Variables

Display Name	Variable Name	I/O and Type	Default Value	Description
Input Matrix	img	Input Image	<active>	Specifies the image to be manipulated and the default input is the active image.
Auto Level	auto	Input int	level	Specifies the leveling method. Option list L:Level Performs leveling on the individual R, G and B channels, treating each of the R, G and B channels as a individual entity. It introduces color cast on the image. C:Contrast Performs leveling on the MASTER channel (the grayscale values of the pixels). No color cast will be introduced. I:Intensity Performs leveling on the RGB channel (the sum of the R, G, and B channels). No color cast will be introduced.
Output Image	oimg	Output Image	<input>	Specifies the output image. By default, it is the same as the input image. See the syntax here.
Level Report	cl	Output ReportData	<new>	Specifies the leveling report.

Description

The imgAutoLevel function applies auto-leveling to an image. It makes the dark values darker and the light values lighter. The function automatically enhances shadows and brightens image by 0.5%. It enhances the contrast and intensity by using the histogram of the image and a color distribution-based algorithm.

The imgLevel function can customize the percentage of white pixels and black pixels to clip from the input image to apply leveling to an image.

Examples

In this example, we use the imgAutoLevel function to increase the contrast of the input image:

When the input image is active, select Image: Adjustments: Auto Level: Contrast. The X-Function is applied and the image is altered. We can see that the contrast has been improved than before.


The original image	The output image

Algorithm

When auto-leveling is applied, 0.5% of the black pixels and 0.5% of the white pixels in the input image is clipped. The computation uses L_AutoColorLevelBitmap()from LEADTOOLS Main API. For more information, please refer to the LEADTOOLS Main API Help file, Version 14 and read the following topic: L_AutoColorLevelBitmap.