2.6.1.8 imgGamma

Contents

Menu Information

Image: Adjustments: Gamma

Brief Information

Apply gamma correction to image

Command Line Usage

1. imgGamma a:=1;

2. imgGamma a:=2.3 img:=mat(1) oimg:=mat(2);

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
Gamma a

Input

double

1.0

Specifies the gamma value. It can be any number greater than 0.

Input Matrix img

Input

Image

<active>

Specifies the source image to be manipulated. The default input is the active image.

Output Image oimg

Output

Image

<input>

Specifies the output image. By default, the output image is the same as the input image.

See the syntax here.

Description

The imgGamma function adjusts the intensity of colors in a bitmap by changing the gamma constant that is used to map the intensity values. Note that a gamma value greater than 1 will in general lead to an intensity increase, while a gamma value less than 1 will cause the intensity to be reduced.

Examples

In this example, we use the imgGamma function to increase the intensity of the input image:

  1. When the input image is active, select Image: Adjustments: Gamma. This opens the dialog of the X-Function.
  2. In the X-Function dialog, change the settings as the screenshot below and click OK to close the dialog.
    ImgGamma help English files image002.jpg
    A new image is created. We can see that it is brighter than the original image.
ImgGamma help English files image004.jpg
ImgGamma help English files image006.jpg
The original image
The output image


Algorithm

The computation uses L_GammaCorrectBitmap() function from LEADTOOLS Main API. Please refer to the LEADTOOLS Main API Help file, Version 14 and read the L_GammaCorrectBitmap topic.

References

LEADTOOLS Main API Help file, Version 14

Related X-Functions

imgBrightness