https://github.com/greg-kennedy/nfo2png
Render ASCII text files to PNG images
https://github.com/greg-kennedy/nfo2png
ansi ascii cp437 nfo png txt
Last synced: 27 days ago
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Render ASCII text files to PNG images
- Host: GitHub
- URL: https://github.com/greg-kennedy/nfo2png
- Owner: greg-kennedy
- License: cc0-1.0
- Created: 2021-02-28T08:02:21.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2021-11-06T06:48:07.000Z (about 4 years ago)
- Last Synced: 2025-04-15T18:40:36.794Z (8 months ago)
- Topics: ansi, ascii, cp437, nfo, png, txt
- Language: Perl
- Homepage:
- Size: 9.77 KB
- Stars: 6
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# nfo2png
*Greg Kennedy, 2021*
Render ASCII text files to PNG images.
## Usage
cat input.txt | ./nfo2png.pl > output.png
## About
This is a tool to render an ASCII text file to a .png output. There is only one code page supported, [CP437](https://en.wikipedia.org/wiki/Code_page_437), and only one choice of font: the [VGA BIOS 9x16 font](https://int10h.org/oldschool-pc-fonts/fontlist/font?ibm_vga_9x16) from the IBM PS/2.
The restrictive set of output formats is deliberate. This script is part of a larger project and is used to render .nfo files, commonly distributed by warez groups along with their releases. NFO files were usually intended for viewing on ANSI-compatible systems, especially MS-DOS, and often featured elaborate ASCII art or logos built from the standard CP437 character set. These systems are rare today: for example, Windows 95 would instead use [Windows-1252](https://en.wikipedia.org/wiki/Windows-1252) by default, replacing many of the box-drawing characters with international characters (accented vowels, etc) instead.
The IBM PS/2, in VGA Text mode, could display 80x25 characters on screen pulled from a 9x16 font. This makes effectively a 720x400 pixel "virtual" screen. However, CRT monitors at the time were exclusively 4:3 which caused the mode to use non-square pixels. In other words, the font at 1:1 appears too wide. The image should be scaled vertically by 1.35x to make a "correct" image. This tool supports integer scaling of the output: with `SCALE_W` of 3, and `SCALE_H` of 4, we achieve a 1.33x vertical increase - quite close to the intended value.
## Config
A few settings are available by editing these constants at the top of the script:
use constant {
MARGIN_W => 0,
MARGIN_H => 0,
SCALE_W => 3,
SCALE_H => 4,
INVERT => 0
};
`MARGIN_W` and `MARGIN_H` add extra padding to the sides and top/bottom of the output. The values are in whole-character units, so `MARGIN_W => 1` creates an 82-column-wide output image, where the left- and right-most columns are always empty. Similarly, `MARGIN_H => 1` effectively adds a blank line to the top and bottom of the output.
`SCALE_W` and `SCALE_H` repeat columns or rows in the output image to perform nearest-neighbor upscaling. The minimum values are 1 for each, and must be whole integer values. As stated earlier, `SCALE_W => 3` and `SCALE_H => 4` achieves a nearly 4:3 aspect ratio as it would appear on legacy hardware.
`INVERT` can be 0 or 1. When set to 1 it swaps the black and white pixels - in other words, the image will become black text on a white background.
## Hacking
The IBM BIOS font is stored as a 16-element list constant, containing long strings of hex characters. Characters are 9 bits wide, which makes editing complicated. These values were obtained by taking a 256x1 image of the IBM character set, converting to .pbm format, and extracting the image data. Perl's `vec()` function works only in little-endian mode, so it was necessary to reverse the bit positions of each byte when creating the font constant.
[Devel::NYTProf](https://metacpan.org/pod/Devel::NYTProf) was helpful in identifying hot areas of the code to improve, allowing me to drastically cut the runtime.