Program to convert image and rotate

I've been trying to make this program in c++ with opencv that converts the image to greyscale and rotates the image afterwards, but the output I get is all kinds of messed up.

I haven't been able to find what the hell I have done wrong so if any of you could help me it'd be great

http://pastebin.com/FSJKyaeU

Install GIMP.

With ImageMagick:
convert input_image.png -colorspace Gray -rotate 90 output_image.png

There's a C++ library for it, so use that if it has to be C++ for some reason.

>>2
>>3
The thing is that i'm trying to actually make a program that rotates the image by using an algorithm, and outputting it as a greyscale image.

>>4
Someone has already done it, and they've done it better than you. Be grateful: now you don't have to do any work!

>>5
I don't think you understand.
This is how I have to do it.

>>1

Check Line 22 again

>>6
The sooner you get over your obsessive-compulsive disorder, the better.

>>7
Yeah, I suspected that's where it goes wrong, but I just can't put my finger on it

>>9

if you can't see the mistake in there, then you need a break.

>>3

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(int argc, char ** argv)
{
  const char * str = new char[512];
  char * d = memchr(argv[1], '.', strlen(argv[1]));
  const char * str2 = new char[512];
  memmove(str2, argv[1], d -  argv[1]);
  str2[d - argv2 + 1] = 0;
  snprintf(str, 512, "%s %s %s%s%s", "convert", argv[1], "-colorspace Gray -rotate 90", str2, "output", argv[1] + d);
  system(str);
  delete [] str; delete [] str2;
  return 0;
}

whoops


#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(int argc, char ** argv)
{
  const char * str = new char[512];
  char * d = memchr(argv[1], '.', strlen(argv[1]));
  const char * str2 = new char[512];
  memmove(str2, argv[1], d -  argv[1]);
  str2[d - argv2 + 1] = 0;
  snprintf(str, 512, "%s %s %s%s%s", "convert", argv[1], "-colorspace Gray -rotate 90", str2, "output", argv[1] + d);
  system(str);
  delete [] str; delete [] str2;
  return 0;
}

whoops


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

int main(int argc, char ** argv)
{
  char * str = malloc(512);
  char * d = memchr(argv[1], '.', strlen(argv[1]));
  char * str2 = malloc(512);
  memcpy(str2, argv[1], d -  argv[1]);
  str2[d - argv[1] + 1] = 0;
  snprintf(str, 512, "%s %s %s %s%s%s", "convert", argv[1], "-colorspace Gray -rotate 90", str2, "output", d);
  system(str);
  free(str); free(str2);
  return 0;
}

,K,¨⊃(⊂⊂¯9 ¯11)+.○¨¨∘.,/⍳¨⍴K
This converts a bitmap K into a value paired with a complex number representing the coordinates.

>>14
Now write it in Lisp.

>>14
Is that symta?

Sepples a shit.

>>15
,K,¨⊃(⊂⊂¯9 ¯11)+.○¨¨∘.,/⍳¨⍴K))))))))))))))))))))))

Paradife Loft

>>1
Just move each pixel to a x*(cos angle), y*(sin angle), then fill result pixels with closest matching rotated-neighbors. Using a simple N-linear interpolation will greatly increase rotation quality.

using namespace std;

i see  your code is off to an amazing start, op

youre going to go far

>>20
You're an idiot. That's not linear interpolation, that's nearest neighbor.

>>9
The problem is that you're truncating on lines 20 and 21. When you rotate an image the resulting coordinates are not going to fall exactly on the pixels and it's going to look like crap.

What you need to do is look up bilinear interpolation. Then, write a function that does that by taking the image and two double coordinates and gives you the value between the pixels. Use that function instead of im.at<unsigned char>.

Also, your rotation matrix is inverted.

>>22
Reading comprehension.