# 1D array to 16bits greyscale mat

**URL:** <https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888>\
**Category:** C++\
**Tags:** mat, core\
**Created:** [June 17, 2021, 12:17am UTC](https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888 "2021-06-17T00:17:09Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![superdu](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@superdu](https://forum.opencv.org/u/superdu)\
**Post date:** [June 17, 2021, 12:17am UTC](https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888/1 "2021-06-17T00:17:09Z")

</div>

hello everyone.

That make a long time now that im blocked  
and i didn’t find solutions yet. I really need your help.

I have a 1d dynamical int array which represent a grayscale image of 8288x5644 pixels. I try to display it using imshow. But the result is not good. I have a matrix of good dimension but with columns of 0 every 2 columns (ex: column 1, 0 , column 2, 0 column 3, o etc…).

I really dont understand why. Here my code and the link at the end is the data file.

**main**

```auto
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include "Fit.h"

using namespace cv;

int main(){

const char* path = "c:/.../light_m51_60.0s_bin1_l_gain60_20210515-015357_-9.4c_0001.fit";
    img Img;
    Fit::open(path, &Img);

float* newImg = new float[Img.totalPixels]; // just for rescale the dynamics of the image
    for (int i = 0; i < Img.totalPixels; i++) {
        newImg[i] = (Img.data[i] - 1000.0) / (9000 - 1000);
        if (newImg[i] < 0)
            newImg[i] = 0;
        if (newImg[i] > 1)
            newImg[i] = 1;
        Img.data[i] = (int)(65355* newImg[i]);

    }
    Mat m(Img.size[1], Img.size[0], CV_16U, Img.data);
    imshow("yolo", m);

}

```

**Fit.h**

```auto
#include "cfitsio/fitsio.h"
#include "GlobalStruct.h"

using namespace std;
class Fit
{
	
public:

    static void open(const char* path, img* Img);

	

private:
	static int getTotalPixel(int dim, long * size);
};

```

**Fit.cpp**

```auto
#include "fit.h"

void Fit::open(const char* path, img * Img) {

    int status = 0;
    int nullval = 0;
    int anynul = 0;
    fitsfile* fptr;
    fits_open_file(&fptr, path, READONLY, &status); // open file
    fits_get_img_dim(fptr, &Img->dim, &status);	// get dim of image (color or gray scale basicly
    Img->size = new long[Img->dim];
    fits_get_img_size(fptr, 2, Img->size, &status); // get size of image (pixels)
    Img->totalPixels = getTotalPixel(Img->dim, Img->size);
    Img->data = new int[Img->totalPixels];
    fits_read_img(fptr, ULONG_IMG, 1, Img->totalPixels, &nullval, Img->data, &anynul, &status);
    fits_close_file(fptr, &status);

}

int Fit::getTotalPixel(int dim, long* size) {
    int multOfAllPixel = 1;
    for (int i = 0; i < dim; i++)
        multOfAllPixel *= size[i];
    return multOfAllPixel;

}

```

**GlobalStruct.h**

```auto
#ifndef GLOBALSTRUCT_H
#define GLOBALSTRUCT_H

//Any type definitions needed
using namespace std;
typedef struct img
{
   
    long * size;
    long totalPixels;
    int dim;
    int *data;

} img;

#endif

```

the link to the file:

[https://www.transfernow.net/dl/202106170bmYcJF3](https://www.transfernow.net/dl/202106170bmYcJF3)

thank you in advance!

---

<div class="post-metadata">

**Author:** ![crackwitz](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/crackwitz/32/14_2.png) [@crackwitz](https://forum.opencv.org/u/crackwitz)\
**Post date:** [June 17, 2021, 6:17am UTC](https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888/2 "2021-06-17T06:17:49Z")

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> [@superdu](#):
>
> ```auto
> Mat m(Img.size[1], Img.size[0], CV_16U, Img.data);
> 
> ```

`Img.data` is of type `float` but by saying `CV_16U` you claim it to be of `unsigned short` (uint16\_t).

you decide what it should be, but be consistent.

you multiplied by `65355` which is probably a typo of `65535`.

I would recommend sticking with float, which is CV\_32F. floats need to be in the range of 0 … 1.

---

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**Author:** ![berak](https://avatars.discourse-cdn.com/v4/letter/b/85f322/32.png) [@berak](https://forum.opencv.org/u/berak)\
**Post date:** [June 17, 2021, 6:53am UTC](https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888/3 "2021-06-17T06:53:29Z")

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> [@superdu](#):
>
> `Mat m(Img.size[1], Img.size[0], CV_16U, Img.data);`

type problem here, your `img` struct has an `int` data pointer  
(4 bytes per pixel, not 2, that’s why every second CV\_16U pixel is 00)

it should be either:

```
Mat m(Img.size[1], Img.size[0], CV_32S, Img.data);

```

(and the range be adjusted)

or `ushort *data` in the Img struct

---

<div class="post-metadata">

**Author:** ![superdu](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@superdu](https://forum.opencv.org/u/superdu)\
**Post date:** [June 17, 2021, 9:29am UTC](https://forum.opencv.org/t/1d-array-to-16bits-greyscale-mat/3888/4 "2021-06-17T09:29:01Z")

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Thank you berak and crackwitz. You helped me a lot. Indeed if i use ushort than int, that solve my problem.