구차니의 잡동사니 모음

1. 롤링셔터 현상((Rolling Shutter) : 가령 이동 중인 자동차 안에서 동영상을 찍으면 건물의 기둥들이 사선으로 기울어져 보입니다.

2. 젤로 현상(Jello Effect) : 카메라를 좌우로 왔다 갔다 하면 가끔 화면 중간이 끊어진 것처럼 보입니다.

3. 워블링 현상(Wobbling Effect) : 진동이 심한 물체위에는 카메라를 고정하더라도 이미지가 춤추듯이 왜곡됩니다.

4. 얼라이어싱 현상(Aliasing Effect), 모아레(Moire) 현상 : 수평직선이 곧게 보이지 않고 계단모양으로 단절되고, 패턴이 일정한 피사체를 찍을 때 빛의 간섭이 일어납니다.

5. 부분 노출 불량(Partial Exposure) : 센서의 노출시간과 이미지 처리시간이 동기화되지 못해서 깜박임이 나타납니다.

6. 기타 : 줌을 할 때 초점이 자동으로 맞지 않는 경우가 많고, 밝은 부분에서 어두운 부분으로 가거나 그 반대인 경우 카메라는 노출조절이 단계적이기 때문에 명암조절이 부드럽지 못하고, 저장시간에도 제한이 있습니다.

[링크 : http://cluster1.cafe.daum.net/...docid=14Asm70Cw2416920120413225725] 

How to overcome negative effects of rolling shutter?

Slow down.

Shoot at slower shutter speeds so the motion blur can mask the rolling shutter effects. Secondly, rolling shutter effects happen when you’re moving quickly, for example whipping your pans. Slow down your pans. Whipping your shots just makes your audience nauseous anyway.

Remove it or blur it.

The obvious answer is if the jello effect is occurring in a subject that is not the primary focus then recompose the shot so the items is not within the scene. For example, if that propeller blade is not necessary, move your camera around so the viewer can no longer see that propeller. If the skew is occurring in something in the background, you can attempt to blur it out by changing your depth of field.

Fix it in post.

There are some plugins and software available to help correct the footage.

[링크 : http://www.dslrvideocollege.com/what-is-rolling-shutter-and-the-jello-effect] 

-D name

Predefine name as a macro, with definition 1. 

-D name=definition

The contents of definition are tokenized and processed as if they appeared during translation phase three in a ‘#define’ directive. In particular, the definition will be truncated by embedded newline characters.

If you are invoking the preprocessor from a shell or shell-like program you may need to use the shell's quoting syntax to protect characters such as spaces that have a meaning in the shell syntax.

If you wish to define a function-like macro on the command line, write its argument list with surrounding parentheses before the equals sign (if any). Parentheses are meaningful to most shells, so you will need to quote the option. With sh and csh, -D'name(args...)=definition' works.

-D and -U options are processed in the order they are given on the command line. All -imacros file and -include file options are processed after all -D and -U options. 

-U name

Cancel any previous definition of name, either built in or provided with a -D option. 

-undef

Do not predefine any system-specific or GCC-specific macros. The standard predefined macros remain defined. 

[링크 : https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html] 

$ cat test.c

#include <stdio.h>

#include <setjmp.h>

jmp_buf pos;

void proc()

{

   static int i = 0;

   ++i;

   if(i<10)

       longjmp(pos, i);

   return;

}

int main()

{

   int a;

   a = setjmp(pos);

   printf("%d\n", a);

   proc();

   return 0;

}

[링크 : http://www.jiniya.net/wp/archives/5030]

[링크 : http://egloos.zum.com/studyfoss/v/5275830]

#include <setjmp.h>

int setjmp(jmp_buf env);

void longjmp(jmp_buf env, int val);

[링크 : http://linux.die.net/man/3/setjmp]

[링크 : http://linux.die.net/man/3/longjmp]