2.6.1.10 imgHisteq

Menu Information

Image: Adjustments: Histequalize

Brief Information

Apply histogram equalization to image

Command Line Usage

imgHisteq cs:=yuv;

imgHisteq cs:=yuv oimg:=mat(2);

Variables

Display
Name
Variable
Name
I/O
and
Type
Default
Value
Description
Color Space cs

Input

int

rgb

Specifies which color space to equalize.
Option list

  • RGB:RGB</center>
    Linearizes the number of pixels across the RGB color space.(separated channels)
  • YUV:YUV
    Linearizes the number of pixels across the YUV color space.(Best results)
  • GRAY:GRAY
    Linearizes the number of pixels per gray level in a gray level representation of the image.
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

This function applies histogram equalization to the input image. We can use it to improve the dynamic range and the contrast of the input image.

Examples

In this example, we use the Histequalize function to boost the contrast of the input image:

  1. When the input image is active, select Image: Adjustments: HistEqualize: Open Dialog. 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.
    ImgHisteq help English files image002.jpg
    We can see that the input image is modified and the contrast is increased.
ImgHisteq help English files image004.jpg
ImgHisteq help English files image006.jpg
The original image
The output image


Algorithm

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

References

LEADTOOLS Main API Help file, Version 14

Related X-Functions

imgBrightness, imgHue, imgSaturation