How to convert image to tensor in golang?

I'm trying to convert this python interface to tensorflow serving into golang:

image = cv2.imread("1.jpg")
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
image = cv2.resize(image, (256, 256))
image = np.expand_dims(image, axis=0)
image = np.true_divide(image, 255)
np.shape(image)

What I'm came up with is:

package main

import (
    "log"
    "image"
    "gocv.io/x/gocv"
)
func main() {
    imageFilePath := "./a.jpg"
    mat := gocv.IMRead(imageFilePath, gocv.IMReadAnyColor)
    if mat.Empty() {
        log.Panic("Can not read Image file : ", imageFilePath)
        return
    } 
    resizeImage := gocv.NewMat()
    gocv.Resize(mat, &resizeImage, image.Point{X: 256, Y: 256}, 0, 0, gocv.InterpolationNearestNeighbor)
 
    img := resizeImage.Clone()
    gocv.CvtColor(resizeImage, &img, gocv.ColorBGRToRGB)
    // equivalent to np.expand_dims(image, axis=0) ? 

}

I've tried to get help from gonum but had no luck plugging it to gocv, so I'm left clueless and appreciate your help about this.