vpImageConvert_hsv.cpp

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 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.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Convert image types.
 */

 
#if defined(_OPENMP)
#include <omp.h>
#endif
 
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpImageConvert.h>
 
BEGIN_VISP_NAMESPACE
  void vpImageConvert::HSV2RGB(const double *hue_, const double *saturation_, const double *value_, unsigned char *rgb,
                               unsigned int size, unsigned int step)
{
  int size_ = static_cast<int>(size);
#if defined(_OPENMP)
#pragma omp parallel for
#endif
  for (int i = 0; i < size_; ++i) {
    double hue = hue_[i], saturation = saturation_[i], value = value_[i];
 
    if (vpMath::equal(saturation, 0.0, std::numeric_limits<double>::epsilon())) {
      hue = value;
      saturation = value;
    }
    else {
      double h = hue * 6.0;
      double s = saturation;
      double v = value;
 
      if (vpMath::equal(h, 6.0, std::numeric_limits<double>::epsilon())) {
        h = 0.0;
      }
 
      double f = h - static_cast<int>(h);
      double p = v * (1.0 - s);
      double q = v * (1.0 - (s * f));
      double t = v * (1.0 - (s * (1.0 - f)));
 
      const int val_2 = 2;
      const int val_3 = 3;
      const int val_4 = 4;
      switch (static_cast<int>(h)) {
      case 0:
        hue = v;
        saturation = t;
        value = p;
        break;
 
      case 1:
        hue = q;
        saturation = v;
        value = p;
        break;
 
      case val_2:
        hue = p;
        saturation = v;
        value = t;
        break;
 
      case val_3:
        hue = p;
        saturation = q;
        value = v;
        break;
 
      case val_4:
        hue = t;
        saturation = p;
        value = v;
        break;
 
      default: // case 5:
        hue = v;
        saturation = p;
        value = q;
        break;
      }
    }
 
    unsigned int i_step = static_cast<unsigned int>(i) * step;
    rgb[i_step] = static_cast<unsigned char>(vpMath::round(hue * 255.0));
    rgb[++i_step] = static_cast<unsigned char>(vpMath::round(saturation * 255.0));
    rgb[++i_step] = static_cast<unsigned char>(vpMath::round(value * 255.0));
    const int val_3 = 3;
    if (i_step == val_3) { // alpha
      ++i_step;
      rgb[i_step] = vpRGBa::alpha_default;
    }
  }
}

void vpImageConvert::HSV2RGB(const unsigned char *hue_, const unsigned char *saturation_, const unsigned char *value_,
                             unsigned char *rgb, unsigned int size, unsigned int step, bool h_full)
{
  const int val_2 = 2;
  const int val_3 = 3;
  const int val_4 = 4;
  float h_max;
  if (h_full) {
    h_max = 255.f;
  }
  else {
    h_max = 180.f;
  }
  int size_ = static_cast<int>(size);
#if defined(_OPENMP)
#pragma omp parallel for
#endif
  for (int i = 0; i < size_; ++i) {
    float hue = hue_[i] / h_max;
    float saturation = saturation_[i] / 255.f;
    float value = value_[i] / 255.f;
 
    if (vpMath::equal(saturation, 0.f, std::numeric_limits<float>::epsilon())) {
      hue = value;
      saturation = value;
    }
    else {
      float h = hue * 6.f;
      float s = saturation;
      float v = value;
 
      if (vpMath::equal(h, 6.f, std::numeric_limits<float>::epsilon())) {
        h = 0.0f;
      }
      float f = h - static_cast<float>(static_cast<int>(h));
      float p = v * (1.0f - s);
      float q = v * (1.0f - (s * f));
      float t = v * (1.0f - (s * (1.0f - f)));
 
      switch (static_cast<int>(h)) {
      case 0:
        hue = v;
        saturation = t;
        value = p;
        break;
 
      case 1:
        hue = q;
        saturation = v;
        value = p;
        break;
 
      case val_2:
        hue = p;
        saturation = v;
        value = t;
        break;
 
      case val_3:
        hue = p;
        saturation = q;
        value = v;
        break;
 
      case val_4:
        hue = t;
        saturation = p;
        value = v;
        break;
 
      default: // case 5:
        hue = v;
        saturation = p;
        value = q;
        break;
      }
    }
 
    unsigned int i_step = static_cast<unsigned int>(i) * step;
    rgb[i_step] = static_cast<unsigned char>(hue * 255.f);
    rgb[++i_step] = static_cast<unsigned char>(saturation * 255.0f);
    rgb[++i_step] = static_cast<unsigned char>(value * 255.0f);
    if (i_step == val_3) { // alpha
      ++i_step;
      rgb[i_step] = vpRGBa::alpha_default;
    }
  }
}

void vpImageConvert::RGB2HSV(const unsigned char *rgb, double *hue, double *saturation, double *value,
                             unsigned int size, unsigned int step)
{
  int size_ = static_cast<int>(size);
  int step_ = static_cast<int>(step);
#if defined(_OPENMP)
#pragma omp parallel for
#endif
  for (int i = 0; i < size_; ++i) {
    double red, green, blue;
    double h, s, v;
    double min, max;
    int i_ = i * step_;
 
    red = rgb[i_] / 255.0;
    ++i_;
    green = rgb[i_] / 255.0;
    ++i_;
    blue = rgb[i_] / 255.0;
 
    if (red > green) {
      max = std::max<double>(red, blue);
      min = std::min<double>(green, blue);
    }
    else {
      max = std::max<double>(green, blue);
      min = std::min<double>(red, blue);
    }
 
    v = max;
 
    if (!vpMath::equal(max, 0.0, std::numeric_limits<double>::epsilon())) {
      s = (max - min) / max;
    }
    else {
      s = 0.0;
    }
 
    if (vpMath::equal(s, 0.0, std::numeric_limits<double>::epsilon())) {
      h = 0.0;
    }
    else {
      double delta = max - min;
 
      if (vpMath::equal(red, max, std::numeric_limits<double>::epsilon())) {
        h = (green - blue) / delta;
      }
      else if (vpMath::equal(green, max, std::numeric_limits<double>::epsilon())) {
        h = 2.0 + ((blue - red) / delta);
      }
      else {
        h = 4.0 + ((red - green) / delta);
      }
 
      h /= 6.0;
      if (h < 0.0) {
        h += 1.0;
      }
      else if (h > 1.0) {
        h -= 1.0;
      }
    }
 
    hue[i] = h;
    saturation[i] = s;
    value[i] = v;
  }
}

void vpImageConvert::RGB2HSV(const unsigned char *rgb, unsigned char *hue, unsigned char *saturation, unsigned char *value,
                             unsigned int size, unsigned int step, bool h_full)
{
  int size_ = static_cast<int>(size);
  std::vector<float> h_scale(4);
  const unsigned int index_0 = 0;
  const unsigned int index_1 = 1;
  const unsigned int index_2 = 2;
  const unsigned int index_3 = 3;
  if (h_full) {
    h_scale[index_0] = 42.5f;
    h_scale[index_1] = 85.f;
    h_scale[index_2] = 170.f;
    h_scale[index_3] = 255.f;
  }
  else {
    h_scale[index_0] = 30.f;
    h_scale[index_1] = 60.f;
    h_scale[index_2] = 120.f;
    h_scale[index_3] = 180.f;
  }
#if defined(_OPENMP)
#pragma omp parallel for
#endif
  for (int i = 0; i < size_; ++i) {
    float red, green, blue;
    float h, s, v;
    float min, max;
    unsigned int i_ = static_cast<unsigned int>(i) * step;
 
    red = rgb[i_];
    green = rgb[++i_];
    blue = rgb[++i_];
 
    if (red > green) {
      max = std::max<float>(red, blue);
      min = std::min<float>(green, blue);
    }
    else {
      max = std::max<float>(green, blue);
      min = std::min<float>(red, blue);
    }
 
    v = max;
 
    if (!vpMath::equal(max, 0.f, std::numeric_limits<float>::epsilon())) {
      s = (255.f * (max - min)) / max;
    }
    else {
      s = 0.f;
    }
 
    if (vpMath::equal(s, 0.f, std::numeric_limits<float>::epsilon())) {
      h = 0.f;
    }
    else {
      float delta = max - min;
 
      if (vpMath::equal(red, max, std::numeric_limits<float>::epsilon())) {
        h = (h_scale[index_0] * (green - blue)) / delta;
      }
      else if (vpMath::equal(green, max, std::numeric_limits<float>::epsilon())) {
        h = h_scale[index_1] + ((h_scale[index_0] * (blue - red)) / delta);
      }
      else {
        h = h_scale[index_2] + ((h_scale[index_0] * (red - green)) / delta);
      }
 
      if (h < 0.f) {
        h += h_scale[index_3];
      }
    }
 
    hue[i] = static_cast<unsigned char>(h);
    saturation[i] = static_cast<unsigned char>(s);
    value[i] = static_cast<unsigned char>(v);
  }
}

void vpImageConvert::HSVToRGBa(const double *hue, const double *saturation, const double *value, unsigned char *rgba,
                               unsigned int size)
{
  const unsigned int val_4 = 4;
  vpImageConvert::HSV2RGB(hue, saturation, value, rgba, size, val_4);
}

void vpImageConvert::HSVToRGBa(const unsigned char *hue, const unsigned char *saturation, const unsigned char *value,
                               unsigned char *rgba, unsigned int size, bool h_full)
{
  const unsigned int val_4 = 4;
  vpImageConvert::HSV2RGB(hue, saturation, value, rgba, size, val_4, h_full);
}

void vpImageConvert::RGBaToHSV(const unsigned char *rgba, double *hue, double *saturation, double *value,
                               unsigned int size)
{
  const unsigned int val_4 = 4;
  vpImageConvert::RGB2HSV(rgba, hue, saturation, value, size, val_4);
}

void vpImageConvert::RGBaToHSV(const unsigned char *rgba, unsigned char *hue, unsigned char *saturation,
                               unsigned char *value, unsigned int size, bool h_full)
{
  const unsigned int val_4 = 4;
  vpImageConvert::RGB2HSV(rgba, hue, saturation, value, size, val_4, h_full);
}

void vpImageConvert::HSVToRGB(const double *hue, const double *saturation, const double *value, unsigned char *rgb,
                              unsigned int size)
{
  const unsigned int val_3 = 3;
  vpImageConvert::HSV2RGB(hue, saturation, value, rgb, size, val_3);
}

void vpImageConvert::HSVToRGB(const unsigned char *hue, const unsigned char *saturation, const unsigned char *value,
                              unsigned char *rgb, unsigned int size, bool h_full)
{
  const unsigned int val_3 = 3;
  vpImageConvert::HSV2RGB(hue, saturation, value, rgb, size, val_3, h_full);
}

void vpImageConvert::RGBToHSV(const unsigned char *rgb, double *hue, double *saturation, double *value,
                              unsigned int size)
{
  const unsigned int val_3 = 3;
  vpImageConvert::RGB2HSV(rgb, hue, saturation, value, size, val_3);
}

void vpImageConvert::RGBToHSV(const unsigned char *rgb, unsigned char *hue, unsigned char *saturation,
                              unsigned char *value, unsigned int size, bool h_full)
{
  const unsigned int val_3 = 3;
  vpImageConvert::RGB2HSV(rgb, hue, saturation, value, size, val_3, h_full);
}
END_VISP_NAMESPACE