Resize only works when n % 4 = 0, when n = 1 or when i resize a 2x2-pixel BMP and n =2

Question

I don't know exactly where is the problem. Resize gives me a bunch of different colors when n % 4 !=0. Can you guys help me understand what I'm doing wrong?

// iterate over infile's scanlines
{
    // resize vertically.
    {
        // iterate over pixels in scanline
        {
            // temporary storage
            // read RGB triple from infile
            // resize horizontally.
            // write RGB triple to outfile
        }
    }

    // skip over padding, if any

    // then add it back (to demonstrate how)
}

Answer 1

If I'm reading the code correctly, it looks like a padding issue. When you are scaling up by any number that requires padding, here's what I see happening. You read in a line of pixels, process it, and write it out, and then go back and repeat this "L" times. However, the code that adds the padding is outside the loop that does this, causing the padding to only be added after the last line of each group. For example, say that you're scaling up by 3. You will read a line of pixels in, process it 3 times, exit the loop and add the padding to the end of the third line before going back to process the next line from the input file.

Restructure so that the padding is added to each line that is sent to the output file and it should work (assuming there are no other bugs).

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