OpenCV  4.5.0-pre
Open Source Computer Vision
Enumerations | Functions
Object Detection

Enumerations

enum  cv::TemplateMatchModes {
  cv::TM_SQDIFF = 0,
  cv::TM_SQDIFF_NORMED = 1,
  cv::TM_CCORR = 2,
  cv::TM_CCORR_NORMED = 3,
  cv::TM_CCOEFF = 4,
  cv::TM_CCOEFF_NORMED = 5
}
 type of the template matching operation More...
 

Functions

void cv::matchTemplate (InputArray image, InputArray templ, OutputArray result, int method, InputArray mask=noArray())
 Compares a template against overlapped image regions. More...
 

Detailed Description

Enumeration Type Documentation

◆ TemplateMatchModes

#include <opencv2/imgproc.hpp>

type of the template matching operation

Enumerator
TM_SQDIFF 
Python: cv.TM_SQDIFF

\[R(x,y)= \sum _{x',y'} (T(x',y')-I(x+x',y+y'))^2\]

with mask:

\[R(x,y)= \sum _{x',y'} \left( (T(x',y')-I(x+x',y+y')) \cdot M(x',y') \right)^2\]

TM_SQDIFF_NORMED 
Python: cv.TM_SQDIFF_NORMED

\[R(x,y)= \frac{\sum_{x',y'} (T(x',y')-I(x+x',y+y'))^2}{\sqrt{\sum_{ x',y'}T(x',y')^2 \cdot \sum_{x',y'} I(x+x',y+y')^2}}\]

with mask:

\[R(x,y)= \frac{\sum _{x',y'} \left( (T(x',y')-I(x+x',y+y')) \cdot M(x',y') \right)^2}{\sqrt{\sum_{x',y'} \left( T(x',y') \cdot M(x',y') \right)^2 \cdot \sum_{x',y'} \left( I(x+x',y+y') \cdot M(x',y') \right)^2}}\]

TM_CCORR 
Python: cv.TM_CCORR

\[R(x,y)= \sum _{x',y'} (T(x',y') \cdot I(x+x',y+y'))\]

with mask:

\[R(x,y)= \sum _{x',y'} (T(x',y') \cdot I(x+x',y+y') \cdot M(x',y') ^2)\]

TM_CCORR_NORMED 
Python: cv.TM_CCORR_NORMED

\[R(x,y)= \frac{\sum_{x',y'} (T(x',y') \cdot I(x+x',y+y'))}{\sqrt{ \sum_{x',y'}T(x',y')^2 \cdot \sum_{x',y'} I(x+x',y+y')^2}}\]

with mask:

\[R(x,y)= \frac{\sum_{x',y'} (T(x',y') \cdot I(x+x',y+y') \cdot M(x',y')^2)}{\sqrt{\sum_{x',y'} \left( T(x',y') \cdot M(x',y') \right)^2 \cdot \sum_{x',y'} \left( I(x+x',y+y') \cdot M(x',y') \right)^2}}\]

TM_CCOEFF 
Python: cv.TM_CCOEFF

\[R(x,y)= \sum _{x',y'} (T'(x',y') \cdot I'(x+x',y+y'))\]

where

\[\begin{array}{l} T'(x',y')=T(x',y') - 1/(w \cdot h) \cdot \sum _{ x'',y''} T(x'',y'') \\ I'(x+x',y+y')=I(x+x',y+y') - 1/(w \cdot h) \cdot \sum _{x'',y''} I(x+x'',y+y'') \end{array}\]

with mask:

\[\begin{array}{l} T'(x',y')=M(x',y') \cdot \left( T(x',y') - \frac{1}{\sum _{x'',y''} M(x'',y'')} \cdot \sum _{x'',y''} (T(x'',y'') \cdot M(x'',y'')) \right) \\ I'(x+x',y+y')=M(x',y') \cdot \left( I(x+x',y+y') - \frac{1}{\sum _{x'',y''} M(x'',y'')} \cdot \sum _{x'',y''} (I(x+x'',y+y'') \cdot M(x'',y'')) \right) \end{array} \]

TM_CCOEFF_NORMED 
Python: cv.TM_CCOEFF_NORMED

\[R(x,y)= \frac{ \sum_{x',y'} (T'(x',y') \cdot I'(x+x',y+y')) }{ \sqrt{\sum_{x',y'}T'(x',y')^2 \cdot \sum_{x',y'} I'(x+x',y+y')^2} }\]

Function Documentation

◆ matchTemplate()

void cv::matchTemplate ( InputArray  image,
InputArray  templ,
OutputArray  result,
int  method,
InputArray  mask = noArray() 
)
Python:
result=cv.matchTemplate(image, templ, method[, result[, mask]])

#include <opencv2/imgproc.hpp>

Compares a template against overlapped image regions.

The function slides through image , compares the overlapped patches of size \(w \times h\) against templ using the specified method and stores the comparison results in result . TemplateMatchModes describes the formulae for the available comparison methods ( \(I\) denotes image, \(T\) template, \(R\) result, \(M\) the optional mask ). The summation is done over template and/or the image patch: \(x' = 0...w-1, y' = 0...h-1\)

After the function finishes the comparison, the best matches can be found as global minimums (when TM_SQDIFF was used) or maximums (when TM_CCORR or TM_CCOEFF was used) using the minMaxLoc function. In case of a color image, template summation in the numerator and each sum in the denominator is done over all of the channels and separate mean values are used for each channel. That is, the function can take a color template and a color image. The result will still be a single-channel image, which is easier to analyze.

Parameters
imageImage where the search is running. It must be 8-bit or 32-bit floating-point.
templSearched template. It must be not greater than the source image and have the same data type.
resultMap of comparison results. It must be single-channel 32-bit floating-point. If image is \(W \times H\) and templ is \(w \times h\) , then result is \((W-w+1) \times (H-h+1)\) .
methodParameter specifying the comparison method, see TemplateMatchModes
maskOptional mask. It must have the same size as templ. It must either have the same number of channels as template or only one channel, which is then used for all template and image channels. If the data type is CV_8U, the mask is interpreted as a binary mask, meaning only elements where mask is nonzero are used and are kept unchanged independent of the actual mask value (weight equals 1). For data tpye CV_32F, the mask values are used as weights. The exact formulas are documented in TemplateMatchModes.
Examples:
samples/cpp/tutorial_code/Histograms_Matching/MatchTemplate_Demo.cpp.