text_computeNMChannels

textfunctionOpenCV 5.0.0

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

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

Explore visually: Text-region detection →

Find candidate text regions before character recognition.

VISUAL WALKTHROUGHText

REFERENCE INPUTText in an image

Characters are pixels before a recognizer assigns text to them.

→

RESULTReturn a text region

Detection returns geometry. Recognition is a separate operation.

Illustrative example. The stages explain the method; they are not a live OpenCV execution.

Compute the different channels to be processed independently in the N&M algorithm [Neumann12].

text_computeNMChannels(_src: Mat, _channels: MatVector, _mode: number): void;

2 available overloads

text_computeNMChannels(_src: Mat, _channels: MatVector): void;

text_computeNMChannels(_src: Mat, _channels: MatVector, _mode: number): void;

_src

Source image. Must be RGB CV_8UC3.

_channels

Output destination, filled by the native operation. Output vector<Mat> where computed channels are stored.

_mode

Mode of operation. Currently the only available options are: ERFILTER_NM_RGBLGrad** (used by default) and ERFILTER_NM_IHSGrad.

In N&M algorithm, the combination of intensity (I), hue (H), saturation (S), and gradient magnitude channels (Grad) are used in order to obtain high localization recall. This implementation also provides an alternative combination of red (R), green (G), blue (B), lightness (L), and gradient magnitude (Grad).

Upstream declaration ↗

These signatures describe this package. Upstream documentation can mention optional backends that are absent from this build. Check runtime compatibility before choosing a backend or file format.