OpenCV  4.10.0
Open Source Computer Vision
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Enumerations | Functions
ColorMaps in OpenCV

Detailed Description

The human perception isn't built for observing fine changes in grayscale images. Human eyes are more sensitive to observing changes between colors, so you often need to recolor your grayscale images to get a clue about them. OpenCV now comes with various colormaps to enhance the visualization in your computer vision application.

In OpenCV you only need applyColorMap to apply a colormap on a given image. The following sample code reads the path to an image from command line, applies a Jet colormap on it and shows the result:

#include <opencv2/core.hpp>
using namespace cv;
#include <iostream>
using namespace std;
int main(int argc, const char *argv[])
{
// We need an input image. (can be grayscale or color)
if (argc < 2)
{
cerr << "We need an image to process here. Please run: colorMap [path_to_image]" << endl;
return -1;
}
Mat img_in = imread(argv[1]);
if(img_in.empty())
{
cerr << "Sample image (" << argv[1] << ") is empty. Please adjust your path, so it points to a valid input image!" << endl;
return -1;
}
// Holds the colormap version of the image:
Mat img_color;
// Apply the colormap:
applyColorMap(img_in, img_color, COLORMAP_JET);
// Show the result:
imshow("colorMap", img_color);
waitKey(0);
return 0;
}
n-dimensional dense array class
Definition mat.hpp:812
bool empty() const
Returns true if the array has no elements.
void imshow(const String &winname, InputArray mat)
Displays an image in the specified window.
int waitKey(int delay=0)
Waits for a pressed key.
CV_EXPORTS_W Mat imread(const String &filename, int flags=IMREAD_COLOR)
Loads an image from a file.
void applyColorMap(InputArray src, OutputArray dst, int colormap)
Applies a GNU Octave/MATLAB equivalent colormap on a given image.
@ COLORMAP_JET
Definition imgproc.hpp:4446
int main(int argc, char *argv[])
Definition highgui_qt.cpp:3
"black box" representation of the file storage associated with a file on disk.
Definition core.hpp:102
STL namespace.
See also
ColormapTypes

Enumerations

enum  cv::ColormapTypes {
  cv::COLORMAP_AUTUMN = 0 ,
  cv::COLORMAP_BONE = 1 ,
  cv::COLORMAP_JET = 2 ,
  cv::COLORMAP_WINTER = 3 ,
  cv::COLORMAP_RAINBOW = 4 ,
  cv::COLORMAP_OCEAN = 5 ,
  cv::COLORMAP_SUMMER = 6 ,
  cv::COLORMAP_SPRING = 7 ,
  cv::COLORMAP_COOL = 8 ,
  cv::COLORMAP_HSV = 9 ,
  cv::COLORMAP_PINK = 10 ,
  cv::COLORMAP_HOT = 11 ,
  cv::COLORMAP_PARULA = 12 ,
  cv::COLORMAP_MAGMA = 13 ,
  cv::COLORMAP_INFERNO = 14 ,
  cv::COLORMAP_PLASMA = 15 ,
  cv::COLORMAP_VIRIDIS = 16 ,
  cv::COLORMAP_CIVIDIS = 17 ,
  cv::COLORMAP_TWILIGHT = 18 ,
  cv::COLORMAP_TWILIGHT_SHIFTED = 19 ,
  cv::COLORMAP_TURBO = 20 ,
  cv::COLORMAP_DEEPGREEN = 21
}
 GNU Octave/MATLAB equivalent colormaps. More...
 

Functions

void cv::applyColorMap (InputArray src, OutputArray dst, InputArray userColor)
 Applies a user colormap on a given image.
 
void cv::applyColorMap (InputArray src, OutputArray dst, int colormap)
 Applies a GNU Octave/MATLAB equivalent colormap on a given image.
 

Enumeration Type Documentation

◆ ColormapTypes

#include <opencv2/imgproc.hpp>

GNU Octave/MATLAB equivalent colormaps.

Enumerator
COLORMAP_AUTUMN 
Python: cv.COLORMAP_AUTUMN
autumn
COLORMAP_BONE 
Python: cv.COLORMAP_BONE
bone
COLORMAP_JET 
Python: cv.COLORMAP_JET
jet
COLORMAP_WINTER 
Python: cv.COLORMAP_WINTER
winter
COLORMAP_RAINBOW 
Python: cv.COLORMAP_RAINBOW
rainbow
COLORMAP_OCEAN 
Python: cv.COLORMAP_OCEAN
ocean
COLORMAP_SUMMER 
Python: cv.COLORMAP_SUMMER
summer
COLORMAP_SPRING 
Python: cv.COLORMAP_SPRING
spring
COLORMAP_COOL 
Python: cv.COLORMAP_COOL
cool
COLORMAP_HSV 
Python: cv.COLORMAP_HSV
HSV
COLORMAP_PINK 
Python: cv.COLORMAP_PINK
pink
COLORMAP_HOT 
Python: cv.COLORMAP_HOT
hot
COLORMAP_PARULA 
Python: cv.COLORMAP_PARULA
parula
COLORMAP_MAGMA 
Python: cv.COLORMAP_MAGMA
magma
COLORMAP_INFERNO 
Python: cv.COLORMAP_INFERNO
inferno
COLORMAP_PLASMA 
Python: cv.COLORMAP_PLASMA
plasma
COLORMAP_VIRIDIS 
Python: cv.COLORMAP_VIRIDIS
viridis
COLORMAP_CIVIDIS 
Python: cv.COLORMAP_CIVIDIS
cividis
COLORMAP_TWILIGHT 
Python: cv.COLORMAP_TWILIGHT
twilight
COLORMAP_TWILIGHT_SHIFTED 
Python: cv.COLORMAP_TWILIGHT_SHIFTED
twilight shifted
COLORMAP_TURBO 
Python: cv.COLORMAP_TURBO
turbo
COLORMAP_DEEPGREEN 
Python: cv.COLORMAP_DEEPGREEN
deepgreen

Function Documentation

◆ applyColorMap() [1/2]

void cv::applyColorMap ( InputArray  src,
OutputArray  dst,
InputArray  userColor 
)
Python:
cv.applyColorMap(src, colormap[, dst]) -> dst
cv.applyColorMap(src, userColor[, dst]) -> dst

#include <opencv2/imgproc.hpp>

Applies a user colormap on a given image.

Parameters
srcThe source image, grayscale or colored of type CV_8UC1 or CV_8UC3. If CV_8UC3, then the CV_8UC1 image is generated internally using cv::COLOR_BGR2GRAY.
dstThe result is the colormapped source image of the same number of channels as userColor. Note: Mat::create is called on dst.
userColorThe colormap to apply of type CV_8UC1 or CV_8UC3 and size 256

◆ applyColorMap() [2/2]

void cv::applyColorMap ( InputArray  src,
OutputArray  dst,
int  colormap 
)
Python:
cv.applyColorMap(src, colormap[, dst]) -> dst
cv.applyColorMap(src, userColor[, dst]) -> dst

#include <opencv2/imgproc.hpp>

Applies a GNU Octave/MATLAB equivalent colormap on a given image.

Parameters
srcThe source image, grayscale or colored of type CV_8UC1 or CV_8UC3. If CV_8UC3, then the CV_8UC1 image is generated internally using cv::COLOR_BGR2GRAY.
dstThe result is the colormapped source image. Note: Mat::create is called on dst.
colormapThe colormap to apply, see ColormapTypes