1d array to grayscale QImage issue

superdu

Hello everyone.

i need your help. I try to display an image which is store on a 1d array. The image is 8288 *5644 grayscale of 16bits/pixel.
for manage this i tried this:

    QImage I((unsigned char*) Image, width , height, width*2, QImage::Format_Grayscale16);
    QPixmap px = QPixmap::fromImage(I);
    ui->label->setPixmap(px);
    ui->label->setScaledContents( true );

i let here two image, one which is the result of the code on the top and the other which is the same image that i exported in 2d csv table and ploted using matplotlib:

of course i can give you the code if the error is not clear to see with this few lines and the data file for debbuging . But they are nothing more than that.

thank you in advance

result
matplotlib plot

VRonin

2 things:

try removing the width*2 argument (Format_Grayscale16 already knows it's 16 bits per pixel)
try removing ui->label->setScaledContents( true ); it might be the scaling algorithm messing up your image. Instead of showing it in a label try saving it to file to see the result

superdu

thank you for your reply and for your time. I tried what you said: save the image give the same result, dont put the *2 next to the width display nothing. i also tried to convert it in 8bits image and just use:

QImage I((unsigned char*) Image, width , height, width, QImage::Format_Grayscale8);

but that not function.

VRonin

@superdu said in 1d array to grayscale QImage issue:

dont put the *2 next to the width display nothing.

No, I meant: QImage I((unsigned char*) Image, width , height, QImage::Format_Grayscale16);

If that still doesn't work you need to tell us what Image is

superdu

here the data: transfernow.net/dl/20210608V8bNa7fC

the code for read data:

fit.cpp

#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 = (long*)malloc(Img->dim * sizeof(long));
    fits_get_img_size(fptr, 2, Img->size, &status); // get size of image (pixels)
    Img->totalPixels = getTotalPixel(Img->dim, Img->size);
    Img->data = (int*)malloc(Img->totalPixels * sizeof(int));
    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;

}

fit.h

#ifndef FIT_H
#define FIT_H

#include "cfitsio/fitsio.h"
#include "GlobalStruct.h"
#include <vector>
#include <utility>

using namespace std;
class Fit
{

public:

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



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



#endif // FIT_H

GlobalStruct

#ifndef FIT_H
#define FIT_H

#include "cfitsio/fitsio.h"
#include "GlobalStruct.h"
#include <vector>
#include <utility>

using namespace std;
class Fit
{

public:

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



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



#endif // FIT_H

mainwindow

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "GlobalStruct.h"
#include "fit.h"
#include <fstream>
#include<iostream>


using namespace std;

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    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 = (float*)malloc(Img.totalPixels * sizeof(float)); // 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)(65535 * newImg[i]);

    }


    QImage I((unsigned char*) Img.data, Img.size[0], Img.size[1], Img.size[0]*2, QImage::Format_Grayscale16);
    QPixmap px = QPixmap::fromImage(I);
    ui->label->setPixmap(px);
}

MainWindow::~MainWindow()
{
    delete ui;
}

superdu

someone have an idea?