matchTemplate

Image processingfunctionOpenCV 5.0.0

import { matchTemplate } from '@banou/opencv-wasm'

Use after await initOpenCV(). See the initialization and named imports guide.

Explore visually: Template matching →

Slide a patch across an image and score how well it agrees at each location.

VISUAL WALKTHROUGHMatching

REFERENCE INPUTSearch image

Find the location of a known 8 × 9 patch within this larger scene.

→

RESULTLocate the best match

The minimum-error response points back to the matching patch in the original image. Correlation-based methods use a different score convention.

Computed teaching example on a 24 × 16 image. Small kernels and simplified settings keep each change visible; use the image laboratory for native OpenCV.

example: samples/cpp/tutorial_code/Histograms_Matching/MatchTemplate_Demo.cpp An example using Template Matching algorithm example: samples/cpp/snippets/mask_tmpl.cpp An example using Template Matching algorithm with mask 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.

matchTemplate(image: Mat, templ: Mat, result: Mat, method: number, mask: Mat): void;

2 available overloads

matchTemplate(image: Mat, templ: Mat, result: Mat, method: number): void;

matchTemplate(image: Mat, templ: Mat, result: Mat, method: number, mask: Mat): void;

image

Image where the search is running. It must be 8-bit or 32-bit floating-point.

templ

Searched template. It must be not greater than the source image and have the same data type.

result

Output destination, filled by the native operation. Map 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) .

method

Parameter specifying the comparison method, see #TemplateMatchModes

mask

Optional 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 type #CV_32F, the mask values are used as weights. The exact formulas are documented in #TemplateMatchModes.

Upstream declaration ↗

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