Normalisation and .TIFF format

Question

I'm currently using OpenCV (in C++) to normalize some data in the form of images. Since I'm planning to train an autoencoder I found some articles and papers suggesting that it's better if the data is normalised in the range from -1 to 1 (tanh vs sin). I managed to do this with the following code:

cv::VideoCapture cap(video);
cv::Mat frame;
cap.read(frame);

//convert to grayscale
cv::cvtColor(*frame, *frame, cv::COLOR_BGR2GRAY);

//normalise
frame->convertTo(*frame, CV_32FC1); //change data type from CV_8UC1 to CV_32FC1
cv::normalize(*frame, *frame, -1, 1, cv::NORM_MINMAX);

//downscale
cv::resize(*frame, *frame, cv::Size(256, 256));

The next thing I want to do is to save the normalised image and for this I'm using cv::imwrite(), so I have the following line: cv::imwrite("normImage.tiff", *frame);.

I'm wondering, however, if writing the image to .TIFF format actually reverses the normalisation and I haven't been able to verify whether that's the case or not. I'd also like to ask if there's a better way/format to write the image using OpenCV?

Cheers