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Format fix 2012/vik/README.md + add alt code

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Based on the author's description I made an alt version that should
theoretically work in Windows though of course (thank goodness) I have
no way to actually test it.

Just like with 2011/vik I've only done this because part of issue #1 is
to make entries work on as many systems as possible though it's not
entirely clear to me that 'Windows' should even be considered a 'system'
at all let alone one worthy of consideration :-)

Updated .gitignore.
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Cody Boone Ferguson committed 2023-05-04 10:08:19 -07:00
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2012/vik/README.md
+78 -46
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@@ -1,8 +1,8 @@
# Best use of cocoa - Bronze award
Daniel Vik
<daniel@vik.cc>
<http://danielvik.com/>
Daniel Vik
<daniel@vik.cc>
<http://danielvik.com/>
## To build:
@@ -10,7 +10,8 @@
make
```
This entry requires [Zlib](http://www.zlib.net/).
This entry requires [Zlib](https://www.zlib.net).
## To run:
@@ -44,6 +45,16 @@ To extract the embedded PNG:
./vik d encodedimg.png > restored.png
```
There is an alternate version which might work for Windows. See Alternate code
section below.
### INABIAF - it's not a bug it's a feature! :-)
The author stated that the program will crash if no argument is passed to the
program or if invalid arguments or images of mismatching sizes or unsupported
pixel formats though we note that your computer might also [halt and catch
fire](https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing)) :-)
## Try:
```sh
@@ -53,45 +64,65 @@ To extract the embedded PNG:
./vik d ioccc-in-chocolate.png > restored-ioccc.png
```
### Alternate code:
Based on the author's description it should be able to get this entry to work
for Windows. With his instructions [Cody Boone
Ferguson](/winners.html#Cody_Boone_Ferguson) added the alternate version that
does this for the few who might use Windows. To compile:
```sh
make alt
```
Use `vik.alt` as you would `vik` above.
We're not sure whether we want to thank Cody or not for this :-) and he's not
sure if he wants to be thanked either :-) but we appreciate it nonetheless.
## Judges' remarks:
References to chocolate had no effect on judging this entry. We
guarantee it.
Can you discern hidden pieces of chocolate in `chocolate-in-ioccc.png`?
Can you discern hidden pieces of chocolate in
[chocolate-in-ioccc.png](chocolate-in-ioccc.png)?
![chocolate in ioccc](chocolate-in-ioccc.png "Chocolate in IOCCC")
## Author's remarks:
### Introduction
This program is a steganography application for embedding an image or text
into another image as well as extracting the embedded image or text back.
The program stores the embedded image or text in the low bits of the RGB
values.
This program is a [steganography](https://en.wikipedia.org/wiki/Steganography)
application for embedding an image or text into another image as well as
extracting the embedded image or text back. The program stores the embedded
image or text in the low bits of the RGB values.
The program supports any 8 bit true color PNG images (RGB, RGBA, grayscale,
and grayscale+alpha). The output image is always 8 bit RGB. When embedding
The program supports any 8 bit true color PNG images (RGB, RGBA, greyscale,
and greyscale+alpha). The output image is always 8 bit RGB. When embedding
one image into another, the width and height needs to be the same.
The program only updates the IDAT and IHDR chunks of the source image. Any
The program only updates the `IDAT` and `IHDR` chunks of the source image. Any
additional chunks are copied into the resulting image.
### Bonus Extractor:
For some reason the chocolate image seems to have some special properties.
Apart from being quite big and a little bit noisy, it appears that when
embedded into another image and extracted, the bitmap data is also a valid
brain$#@$ program. It is of course possible to get the bitmap data from the
extracted image, and run it through any of the previous winning brain$#@$
interpreters, but I thought it would be easier to include an interpreter in
the program to avoid the hassle:
For some reason the chocolate image seems to have some special properties.
Apart from being quite big and a little bit noisy, it appears that when embedded
into another image and extracted, the bitmap data is also a valid
[brain$#@$](https://en.wikipedia.org/wiki/Brainfuck) program. It is of course
possible to get the bitmap data from the extracted image, and run it through any
of the previous winning brain$#@$ interpreters, but I thought it would be easier
to include an interpreter in the program to avoid the hassle:
```sh
./vik e ioccc.png chocolate.png > encodedimg.png
./vik b encodedimg.png
```
It is of course also possible to embed a brain$#@$ program as a text file
It is of course also possible to embed a
[brain$#@$](https://en.wikipedia.org/wiki/Brainfuck) program as a text file
(as explained above) and decode it, e.g.:
```sh
@@ -101,26 +132,25 @@ It is of course also possible to embed a brain$#@$ program as a text file
### Obfuscation
I really wanted to keep the program simple, so instead of adding multiple
macros or helper methods that can be confusing, I placed all functionality
in the main function. Main is called recursively and quite extensively, but
it gives the benefit that all invocations of the function has the same
parameters, argv and argc. This really helps readability, as a programmer
doesn't need to remember several variable or function names. I also tried
to reduce the number of keywords, and the program only has four for-loops
followed by a single return statement. There is a little bit of use of the
question mark operator, but this is really there to keep the program as
simple as possible.
I really wanted to keep the program simple, so instead of adding multiple macros
or helper methods that can be confusing, I placed all functionality in the
`main()` function. `main()` is called recursively and quite extensively, but it
gives the benefit that all invocations of the function have the same parameters,
`argv` and `argc`. This really helps readability, as a programmer doesn't need
to remember several variable or function names. I also tried to reduce the
number of keywords, and the program only has four for-loops followed by a single
return statement. There is a little bit of use of the ternary (`?:`) operator,
but this is really there to keep the program as simple as possible.
### Portability
The program is portable to most platforms that have zlib available. The
only system dependency is that the program relies on writing binary data to
stdout.
The program is portable to most platforms that have [zlib](https://www.zlib.net)
available. The only system dependency is that the program relies on writing
binary data to stdout.
By default, Microsoft compilers adds carriage returns to new lines, and to
By default, Microsoft compilers adds carriage returns to new lines, and to
compile the program on this platform, the following line can be added after
the variable declarations in the main declaration in order to run
the variable declarations in the main declaration in order to run
correctly:
```c
@@ -129,31 +159,33 @@ _setmode(_fileno(stdout), 0x8000);
### Limitations
The program doesn’t have many error checks so passing in invalid arguments
The program doesn't have many error checks so passing in invalid arguments
or images of mismatching sizes, or unsupported pixel formats will cause the
program to crash.
### Extendability
Since a lot of care was taken to keep the code simple, it turned out to be
quite easy to extend functionality. I did include a small brain$#@$ after I
Since a lot of care was taken to keep the code simple, it turned out to be
quite easy to extend functionality. I did include a small
[brain$#@$](https://en.wikipedia.org/wiki/Brainfuck) after I
realized that the chocolate image had some interesting properties.
But there is more functionality I added that didn’t fit within the size
limits and could not remain included. For example, I added a method to
format source code based on a PNG image. So the format of the program is
But there is more functionality I added that didn't fit within the size
limits and could not remain included. For example, I added a method to
format source code based on a PNG image. So the format of the program is
actually done by the program itself.
And to be honest, the chocolate image did not have a brain$#@$ program
embedded to begin with. I added functionality to the program to embed a
brain$#@$ into a PNG image and used it to create the image provided with
And to be honest, the chocolate image did not have a
[brain$#@$](https://en.wikipedia.org/wiki/Brainfuck) program
embedded to begin with. I added functionality to the program to embed a
brain$#@$ into a PNG image and used it to create the image provided with
the entry.
I also added a method to analyze PNG images, to print the size and format,
I also added a method to analyze PNG images, to print the size and format,
as well as the scan line filters.
All these features were quite easy to add, much thanks to the (actually
All these features were quite easy to add, much thanks to the (actually
pretty good) design of the code.
## Copyright and CC BY-SA 4.0 License: