PxThresholdImage

Arguments

Returns

A PhImage.

Description

This function converts greys to black and white, at a given threshold point. As the threshold increases, the image darkens.

Example

This example, ex_PxThresholdImage.g, is included in the product distribution.

#!/usr/cogent/bin/phgamma

/*
The following example demonstrates PxCopyImage(), PxGreyImage(),
and PxThresholdImage().  An image is loaded and converted to grey
scales.  Then four threshold images are created.
*/

PtInit(nil);
require_lisp("PhotonWidgets.lsp");

win = new(PtWindow);

// Load and display the image.
pic1 = PxLoadImage("taj.bmp");
lab1 = new(PtLabel);
lab1.label_type = Pt_IMAGE;
lab1.label_data = pic1;

// Copy the image and convert the colors to grey scales.
pic2 = PxCopyImage(pic1);
pic2 = PxGreyImage(pic2);
lab2 = new(PtLabel);
lab2.label_type = Pt_IMAGE;
lab2.label_data = pic2;
lab2.SetPos(300,0);

// Copy the grey_scale and make a threshold image
// with a medim_level threshold and reversed high/low.
pic3 = PxCopyImage(pic2);
pic3 = PxThresholdImage(pic3, 150, -2, 1);
lab3 = new(PtLabel);
lab3.label_type = Pt_IMAGE;
lab3.label_data = pic3;
lab3.SetPos(600,0);

// Copy the grey_scale and make a threshold image
// with a low_level threshold.
pic4 = PxCopyImage(pic2);
pic4 = PxThresholdImage(pic4, 100, 1, -2);
lab4 = new(PtLabel);
lab4.label_type = Pt_IMAGE;
lab4.label_data = pic4;
lab4.SetPos(0,200);

// Copy the grey_scale and make a threshold image
// with a medium_level threshold.
pic5 = PxCopyImage(pic2);
pic5 = PxThresholdImage(pic5, 150, 1, -2);
lab5 = new(PtLabel);
lab5.label_type = Pt_IMAGE;
lab5.label_data = pic5;
lab5.SetPos(300,200);

// Copy the grey_scale and make a threshold image
// with a high_level threshold.
pic6 = PxCopyImage(pic2);
pic6 = PxThresholdImage(pic6, 200, 1, -2);
lab6 = new(PtLabel);
lab6.label_type = Pt_IMAGE;
lab6.label_data = pic6;
lab6.SetPos(600,200);

PtRealizeWidget(win);
PtMainLoop();

See Also

PxCopyImage, PxGreyImage, PxConvolveImage