Possible Loss of Data during Double to Unsigned Char Conversion?

[DavyS]

Hello. I am currently trying to copy an array of ‘double’ values into an array of “unsigned char”.

I have checked my code to know that the expected values in 2 dimensional double arrays, sig_out_imageR, sig_out_imageG and sig_out_imageB are correct (values were written to a file).

I am currently trying to get these values into a 1 dimensional array of unsigned char for later processing. However, the values are incorrect (normally down by 1). For example, instead of the value being 36, it’s 35, or instead of the value being 204, it’s 203.

I have tried casting the double to an unsigned char in hope of preventing loss of data but this clearly hasn’t helped.

I am using Visual Studio 2010. Would appreciate to learn how to fix this error, thank you.

//put RGB from 2D array contents back into a 1D array
unsigned char* array_1D_RGB_FFT;
array_1D_RGB_FFT = new unsigned char[height*width*bytesPerPixel];
if (array_1D_RGB_FFT == NULL) return 0;  // return if memory not allocated 

ofstream RGBdata1D;
RGBdata1D.open("RGBdata1D.txt");

int offset = 0;
int counter = 0;
int bytesPerPixel = 3;
	
for (int j = 0; j<height; j++)  // traverse height (or rows) 
{
    offset = width * bytesPerPixel * j;
    for (int i = 0; i<width*bytesPerPixel; i+= bytesPerPixel) // width  
   {
       array_1D_RGB_FFT[offset + i + 0] = static_cast<unsigned char>(sig_out_imageB[j][counter]);
       array_1D_RGB_FFT[offset + i + 1] = static_cast<unsigned char>(sig_out_imageG[j][counter]);
       array_1D_RGB_FFT[offset + i + 2] = static_cast<unsigned char>(sig_out_imageR[j][counter]);

       RGBdata1D << "B: " <<(int)array_1D_RGB_FFT[offset + i + 0]
	            << " G: " <<(int)array_1D_RGB_FFT[offset + i + 1]
	             << " R: " <<(int)array_1D_RGB_FFT[offset + i + 2]<< endl;

         ++counter;

   }
	
 counter = 0;

}

RGBdata1D << "count of pixels: " <<c<< endl;
RGBdata1D.close();