Visual Servoing Platform  version 3.6.1 under development (2024-06-12)

Create a sub-image from an image by cropping a rectangular area.Read an image from the disk, crop a rectangular area and save the cropped image on the disk.

* ViSP, open source Visual Servoing Platform software.
* Copyright (C) 2005 - 2023 by Inria. All rights reserved.
* This software is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* See the file LICENSE.txt at the root directory of this source
* distribution for additional information about the GNU GPL.
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* GPL, please contact Inria about acquiring a ViSP Professional
* Edition License.
* See for more information.
* This software was developed at:
* Inria Rennes - Bretagne Atlantique
* Campus Universitaire de Beaulieu
* 35042 Rennes Cedex
* France
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* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* Description:
* Test for sub-image extraction.
#include <visp3/core/vpDebug.h>
#include <visp3/core/vpImage.h>
#include <visp3/core/vpImageTools.h>
#include <visp3/core/vpIoTools.h>
#include <visp3/core/vpRect.h>
#include <visp3/io/vpImageIo.h>
#include <visp3/io/vpParseArgv.h>
#include <stdlib.h>
using namespace VISP_NAMESPACE_NAME;
// List of allowed command line options
#define GETOPTARGS "cdi:o:h"
Print the program options.
\param name : Program name.
\param badparam : Bad parameter name.
\param ipath: Input image path.
\param opath : Output image path.
\param user : Username.
void usage(const char *name, const char *badparam, const std::string &ipath, const std::string &opath,
const std::string &user)
fprintf(stdout, "\n\
Read an image from the disk (Klimt.pgm), crop a rectangular area\n\
and save the cropped image on the disk (Klimt_cropped.pgm).\n\
%s [-i <input image path>] [-o <output image path>]\n\
fprintf(stdout, "\n\
OPTIONS: Default\n\
-i <input image path> %s\n\
Set image input path.\n\
From this path read \"Klimt/Klimt.pgm\"\n\
Setting the VISP_INPUT_IMAGE_PATH environment\n\
variable produces the same behaviour than using\n\
this option.\n\
-o <output image path> %s\n\
Set image output path.\n\
From this directory, creates the \"%s\"\n\
subdirectory depending on the username, where \n\
Klimt_cropped.pgm output image is written.\n\
Print the help.\n\n",
ipath.c_str(), opath.c_str(), user.c_str());
if (badparam)
fprintf(stdout, "\nERROR: Bad parameter [%s]\n", badparam);
bool getOptions(int argc, const char **argv, std::string &ipath, std::string &opath, const std::string &user)
const char *optarg_;
int c;
while ((c = vpParseArgv::parse(argc, argv, GETOPTARGS, &optarg_)) > 1) {
switch (c) {
case 'i':
ipath = optarg_;
case 'o':
opath = optarg_;
case 'h':
usage(argv[0], nullptr, ipath, opath, user);
return false;
case 'c':
case 'd':
usage(argv[0], optarg_, ipath, opath, user);
return false;
if ((c == 1) || (c == -1)) {
// standalone param or error
usage(argv[0], nullptr, ipath, opath, user);
std::cerr << "ERROR: " << std::endl;
std::cerr << " Bad argument " << optarg_ << std::endl << std::endl;
return false;
return true;
int main(int argc, const char **argv)
try {
std::string env_ipath;
std::string opt_ipath;
std::string opt_opath;
std::string ipath;
std::string opath;
std::string filename;
std::string username;
// Get the visp-images-data package path or VISP_INPUT_IMAGE_PATH
// environment variable value
// Set the default input path
if (!env_ipath.empty())
ipath = env_ipath;
// Set the default output path
#if defined(_WIN32)
opt_opath = "C:/temp";
opt_opath = "/tmp";
// Get the user login name
// Read the command line options
if (getOptions(argc, argv, opt_ipath, opt_opath, username) == false) {
// Get the option values
if (!opt_ipath.empty())
ipath = opt_ipath;
if (!opt_opath.empty())
opath = opt_opath;
// Append to the output path string, the login name of the user
opath = vpIoTools::createFilePath(opath, username);
// Test if the output path exist. If no try to create it
if (vpIoTools::checkDirectory(opath) == false) {
try {
// Create the dirname
catch (...) {
usage(argv[0], nullptr, ipath, opt_opath, username);
std::cerr << std::endl << "ERROR:" << std::endl;
std::cerr << " Cannot create " << opath << std::endl;
std::cerr << " Check your -o " << opt_opath << " option " << std::endl;
// Compare ipath and env_ipath. If they differ, we take into account
// the input path coming from the command line option
if (opt_ipath.empty()) {
if (ipath != env_ipath) {
std::cout << std::endl << "WARNING: " << std::endl;
std::cout << " Since -i <visp image path=" << ipath << "> "
<< " is different from VISP_IMAGE_PATH=" << env_ipath << std::endl
<< " we skip the environment variable." << std::endl;
// Test if an input path is set
if (opt_ipath.empty() && env_ipath.empty()) {
usage(argv[0], nullptr, ipath, opt_opath, username);
std::cerr << std::endl << "ERROR:" << std::endl;
std::cerr << " Use -i <visp image path> option or set VISP_INPUT_IMAGE_PATH " << std::endl
<< " environment variable to specify the location of the " << std::endl
<< " image path where test images are located." << std::endl
<< std::endl;
// Here starts really the test
vpImage<unsigned char> I; // Input image
vpImage<unsigned char> C; // Cropped output image
// Read the input grey image from the disk
filename = vpIoTools::createFilePath(ipath, "Klimt/Klimt.pgm");
std::cout << "Read image: " << filename << std::endl;
vpImageIo::read(I, filename);
// Specify the cropping area
vpRect roi;
// Create the cropped image
vpImageTools::crop(I, roi, C);
// Write the cropped image on the disk
filename = vpIoTools::createFilePath(opath, "Klimt_crop.pgm");
std::cout << "Write cropped image: " << filename << std::endl;
vpImageIo::write(C, filename);
catch (const vpException &e) {
std::cout << "Catch an exception: " << e.getStringMessage() << std::endl;
error that can be emitted by ViSP classes.
Definition: vpException.h:60
const std::string & getStringMessage() const
Definition: vpException.cpp:67
static void read(vpImage< unsigned char > &I, const std::string &filename, int backend=IO_DEFAULT_BACKEND)
Definition: vpImageIo.cpp:147
static void write(const vpImage< unsigned char > &I, const std::string &filename, int backend=IO_DEFAULT_BACKEND)
Definition: vpImageIo.cpp:291
static void crop(const vpImage< Type > &I, double roi_top, double roi_left, unsigned int roi_height, unsigned int roi_width, vpImage< Type > &crop, unsigned int v_scale=1, unsigned int h_scale=1)
Definition: vpImageTools.h:313
unsigned int getWidth() const
Definition: vpImage.h:246
static std::string getViSPImagesDataPath()
Definition: vpIoTools.cpp:1847
static bool checkDirectory(const std::string &dirname)
Definition: vpIoTools.cpp:837
static std::string getUserName()
Definition: vpIoTools.cpp:730
static std::string createFilePath(const std::string &parent, const std::string &child)
Definition: vpIoTools.cpp:2210
static void makeDirectory(const std::string &dirname)
Definition: vpIoTools.cpp:986
static bool parse(int *argcPtr, const char **argv, vpArgvInfo *argTable, int flags)
Definition: vpParseArgv.cpp:71
Defines a rectangle in the plane.
Definition: vpRect.h:79
void setHeight(double h)
Definition: vpRect.h:308
void setWidth(double w)
Definition: vpRect.h:378
void setTop(double pos)
Definition: vpRect.h:357
void setLeft(double pos)
Definition: vpRect.h:321