Pixel Art Scaling programs

Programs for scaling up small low-color images like icons and game sprites without blurring.

Apparently useful for scaling up grey text scans with low resolution before OCR, to improve OCR quality.

Currently Scale2x (aka AdvMAME2x), Scale3x (aka AdvMAME3x), Scale2xSFX and Scale3xSFX methods are implemented.

ScaleNxGUI.py is a common shell joining together image formats reading/writing and image rescaling modules. Program provides suitable GUI to access both single file and batch files processing.

ScaleNxGUI

[!NOTE] In version 25.08.22.22 PNG compression options and PPM/PGM format preferences may be saved to disk as JSON file scalenx.ini, edited with any text editor, and loaded back to ScaleNx. Currently file is saved to your user directory (for easy access location is copied to clipboard when saving). Simply point you mouse to status field right above “Exit” button to display the reminder.

[!CAUTION] Batch processing programs replace original files with scaled copies. Batch processing programs in this version use async multiprocessing, thus drastically reducing processing time but loading all CPUs at 100% and rendering GUI almost unresponsive.

Sample of Scale3x (twice)

Dependencies

1. PyPNG. Copy included into current ScaleNx distribution.
2. PyPNM. Copy included into current ScaleNx distribution.
3. Multiprocessing. Included into standard CPython distribution.
4. Tkinter. Normally included into standard CPython distribution for “big” OS-es, although Linux users may need installing it separately.

[!NOTE] Programs are written entirely on Python, using image representation as list of lists of lists. While this representation is logical for human understanding, Python processing of this is slow. Moreover, programs contain lists reshaping for PNG I/O purposes, also performed using Python native means only. As a result, programs are slow but quite compatible with anything capable of running Python, and don’t require large external packages causing version conflicts.

References

1. Scale2x and Scale3x algorithms description by the inventor, Andrea Mazzoleni.

2. Scale2xSFX and Scale3xSFX algorithms description at forums archive.

3. Pixel-art scaling algorithms review at Wikipedia.

Related

Dnyarri website - more Python freeware by the same author.

ScaleNx page with illustrations, explanations etc.

ScaleNx source at github

ScaleNx source at gitflic mirror

ScaleNx at PyPI - install current ScaleNx core library via pip. Does not contain shell, image I/O, and GUI, only ScaleNx core for developers.