Why i get wrong horizontal resize

Question

I\m really stuck in the formula for horizontal resize.For my new padding if i enter 4 for (n) i get for my new padding answer 1, is that correct?

   fpos_t startline;
   for (int a = 0, biHeight = abs(bi.biHeight); a < biHeight; a++)
    {
       for(s = 0; s < n; s++)
         if s < 0
       fgetpos(inptr, &startline);  
       fsetpos(inptr, &startline);
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
            // temporary storage
            RGBTRIPLE triple;

             //verticaly works...
         }

        // skip over padding, if any
        fseek(inptr, -padding, SEEK_CUR);

        // then add it back (to demonstrate how)

        for (int k = 0; k < newpadding; k++)
        {

            fputc(0x00, outptr);
        }

    }

So it go's from 0 to abs height and if it ends should return me start position and write it, but i've got only 3 lines. Where I make mistake ??

This is what i get from peek check:

And when i check with xxd with student version when i resize with 4 i get this:

I'm sure that something is skipped, but I can't found my mistake. Thanks!

Answer 1

This is saying that your header info is wrong for sizeimage and bfsize. Don't forget that you need to recalculate padding values as well, and that changes in padding will affect the overall size of the image.

pseudocode for resize:

//for every row in the source file, if iterations of for loop is less than the multiplier, run again <-you need to add this

 //for every RGB triple in the source file, if iterations of for loop for width is less than the multiplier, run again   <--you have

this entire piece done

what you are currently doing:

source file

> RGBTRIPLE

and if the multiplier is 4 you are outputting:

> RGBTRIPLE RGBTRIPLE RGBTRIPLE RGBTRIPLE 

but you need to output:

> RGBTRIPLE RGBTRIPLE RGBTRIPLE RGBTRIPLE 
> RGBTRIPLE RGBTRIPLE RGBTRIPLE RGBTRIPLE 
> RGBTRIPLE RGBTRIPLE RGBTRIPLE RGBTRIPLE 
> RGBTRIPLE RGBTRIPLE RGBTRIPLE RGBTRIPLE 

4 times the height AND width. You need a for loop for the height, and nested inside of that, a for loop for the width.