pset4 resizing not resizing my image

Question

I'm trying to do pset 5 and can not seem to resize my image, I tried many different way to formulate the image size but somehow its not working, I was wondering if anyone can spot what I am doing wrong? much appreciated for anyone's help, here is the code:

#include <stdio.h>
#include <stdlib.h>

#include "bmp.h"

int main(int argc, char* argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        printf("Usage: ./copy infile outfile\n");
        return 1;
    }

    // resizing the varible

    int resize = atoi(argv[1]);

    // checking invalid resize values
    if (resize < 0 || resize > 100)
    {
        printf("Resize must be between 1 and 100 \n");
        return 2;
    }

    // remember filenames
    char* infile = argv[2];
    char* outfile = argv[3];

    // open input file 
    FILE* inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        printf("Could not open %s.\n", infile);
        return 3;
    }

    // open output file
    FILE* outptr = fopen(outfile, "w");
    if (outptr == NULL)
    {
        fclose(inptr);
        fprintf(stderr, "Could not create %s.\n", outfile);
        return 4;
    }

    // read infile's BITMAPFILEHEADER
    BITMAPFILEHEADER bf;
    fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);

    // read infile's BITMAPINFOHEADER
    BITMAPINFOHEADER bi;
    fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);

    // ensure infile is (likely) a 24-bit uncompressed BMP 4.0
    if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 || 
        bi.biBitCount != 24 || bi.biCompression != 0)
    {
        fclose(outptr);
        fclose(inptr);
        fprintf(stderr, "Unsupported file format.\n");
        return 4;
    }

    // making varibles for bitmap headers for resizefile
    BITMAPFILEHEADER resize_bf;
    BITMAPINFOHEADER resize_bi;
    resize_bf = bf;
    resize_bi = bi;
    // updating by the size factor
    resize_bi.biWidth = bi.biWidth * resize;
    resize_bi.biHeight = bi.biHeight * resize; 

     // determine padding for scanlines
    int padding =  (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    // determine the padding for resizing it with its factor
    int outPadding = (4 - (resize_bi.biWidth *sizeof(RGBTRIPLE)) % 4) % 4;

// THIS FORMULATION I NEED TO FIGURE OUT CORRECTLY // calculating file and image size from formulating the following

resize_bi.biSizeImage = (resize_bi.biWidth * sizeof(RGBTRIPLE) + outPadding) * abs(resize_bi.biHeight); // resize_bf.bfSize = bf.bfSize - bi.biSizeImage + resize_bi.biSizeImage; resize_bf.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + resize_bi.biSizeImage;

// write outfile's BITMAPFILEHEADER
fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outptr);

// write outfile's BITMAPINFOHEADER
fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outptr);

// iterate over infile's scanlines
for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
{

    // write each line for resize times
    for (int s = 0; s < resize; s++)
    {


    // iterate over pixels in scanline
    for (int j = 0; j < bi.biWidth; j++)
    {
        // temporary storage for width
        RGBTRIPLE triple;

        // read RGB triple from infile
        fread(&triple, sizeof(RGBTRIPLE), 1, inptr);

        // write the tripled size to the outfile
        for (int t = 0; t < resize; t++)
        {

            // write RGB triple to outfile for horizontal update
            fwrite(&triple,sizeof(RGBTRIPLE), 1, outptr);
        }
    }




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

    // then add it back (to demonstrate how)
    for (int k = 0; k < padding; k++)
    {
        fputc(0x00, outptr);
    }

    // more skipping for resize padding if its odd number of bytes
    fseek(inptr, -(bi.biWidth * 3 + padding),SEEK_CUR);
    }

 // same as above but for other direction   
 fseek(inptr, bi.biWidth * 3 + padding, SEEK_CUR);

}

// close infile
fclose(inptr);

// close outfile
fclose(outptr);

// that's all folks
return 0;

}

Answer 1

You have 3 errors, essentially all the same problem. In short, you're writing input file vars and values to the output file.

You're writing out both input file headers instead of the modified output file headers (breaking all except resize = 1), and you're using the input padding variable as the control in the for loop when writing padding to the output file when you should be using outPadding.

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