convertTo

Usage

Converts the data type of an image to another with optional scaling. You can adjust the value range of the image by specifying the target data type and scaling factor.

Interface

void Mat::convertTo(OutputArray dst, int type_, double alpha, double beta) const;

Parameters

Parameter	Description	Value Range	Input/Output
dst	Output image.	Mat class	Output
type_	Target data type.	(CV_8U, CV_64F)	Input
alpha	(Optional) Scaling factor. The default value is 1.	(-inf, inf)	Input
beta	(Optional) Offset. The default value is 0.	(-inf, inf)	Input

Return Values

Success: KP_CV_SUCCESS
Failure: an error code

Error Codes

Error Code	Description
INVALID_PARAM_MSG	The input image is null.
NOT_SUPPORT_MSG	The input image type is incorrect or the type_ value is not supported.

Example

#include <opencv2/opencv.hpp>
#include <iostream>

int main() {
    // Create a 5x5 image.
    cv::Mat src = (cv::Mat_<uint8_t>(5, 5) << 0, 0, 0, 0, 0,
                                              0, 1, 1, 1, 0,
                                              0, 1, 0, 1, 0,
                                              0, 1, 1, 1, 0,
                                              0, 0, 0, 0, 0);

    // Convert the data type of the image from 8-bit unsigned integers to 32-bit floating point numbers and scale the image.
    cv::Mat dst;
    src.convertTo(dst, CV_32F);  // Data type conversion
    cv::convertScaleAbs(dst, dst, 2.0, 0); // Image scaling

    // Output image
    std::cout << dst << std::endl;

    return 0;
}

Output:

[[ 0  0  0  0  0]
 [ 0  2  2  2  0]
 [ 0  2  0  2  0]
 [ 0  2  2  2  0]
 [ 0  0  0  0  0]]

Parent topic: Interface Definition