Guardian_LTSM

Table of Contents

• Overview
• Installation
• Libraries
• Usage
• 1-Bit Converter
• Colour Converter
• Output
• Configuration file
• Screenshots
• See Also

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Overview

Guardian_LTSM is a Python GUI tool for converting images into C/C++ byte arrays suitable for use with embedded systems, OLED displays, LCDs, and microcontroller projects.

It provides two conversion pipelines:

• 1-Bit Converter — Convert greyscale/monochrome images to 1-bit bitmap arrays, or convert existing 1-bit C arrays back to images. Supports horizontal and vertical addressing modes as used by common OLED display drivers (e.g. SSD1306).

• Colour Converter — Convert colour images into raw byte arrays across multiple colour depth formats (4, 8, 15, 16, 24, 32-bit). Supports multiple output formats and data type options suitable for colour LCD and TFT display drivers.

• GUI built with Tkinter

• Lightweight: only depends on Pillow

• Configurable input/output paths and preview sizes

Installation

1. Github repository
2. Arch Linux AUR
3. Pypi package

The program is present in the Python Package Index, PyPI. Install (you can use pip or pipx) to the location or environment of your choice.

# For example with pipx
pipx install guardian-ltsm

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Libraries

Pillow for image processing

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Usage

0. Github repository: Guardian_LTSM
1. PyPI package name: guardian-ltsm
2. Import path: import guardian_ltsm
3. Executable command: guardian

Run the GUI:

Select from the application menu (if desktop entry installed) or run from terminal with:

guardian
# or directly with Python
python3 -m guardian_ltsm.guardian_main

The main menu presents two options:

• 1-Bit Converter — opens the 1-bit image/data conversion tool
• Colour Converter — opens the colour image conversion tool

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1-Bit Converter

The 1-bit converter has two paths selectable from the main menu:

Image to Data

1. Load a PNG, BMP, JPG, or GIF image
2. Adjust image settings:
   • Threshold — slider (0–255) controls the greyscale cutoff for black/white conversion
   • Invert — invert the bitmap
3. Adjust output settings:
   • Image Name — variable name used in the C array declaration
   • File Name — output file name
   • File Type — .h or .hpp
   • Draw Mode — Horizontal or Vertical addressing
   • Swap Bits in Byte — mirror bit order within each byte
4. Click Output to save the header file. Data is also copied to clipboard automatically.

Data to Image

1. Paste a raw C byte array (0x00 format) into the dialog
2. Enter image width and height in pixels
3. Select addressing mode (Horizontal or Vertical)
4. Click Convert to Image — the image is rendered in the preview
5. Click Output to save as PNG or BMP

Example output:

// Generated by Guardian LTSM - One Bit Converter
// Image Name  : my_image
// Dimensions  : 84 x 24 px
// Data Size   : 252 bytes
// Draw Mode   : Vertical
// Swap Bits   : No
// Threshold   : 128
// Inverted    : No
const uint8_t my_image[] = {
    0xFF, 0x00, 0x1C, 0x22, 0x22, 0x1C, 0x00, 0xFF, ...
};

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Colour Converter

1. Load a PNG, BMP, JPG, or GIF image — file info and preview are displayed
2. Adjust conversion settings:

Setting	Description
Palette Mode	Colour depth and format of the output data
Resize	Optional resize before conversion. Fill one field only to maintain aspect ratio
Output Format	Hex (0x00), Decimal, or Binary (0b00000000)
Endianness	Little-endian or Big-endian byte order (affects 16-bit modes)
Data Type	Array element type: uint8_t, uint16_t, uint32_t
Multi-line	One row of pixels per line in the output array
Separate bytes	Each byte is its own array element. When off, bytes are packed into elements matching the data type size
Image Name	Variable name used in the C array declaration

3. Click Convert — data appears in the result panel and a converted preview is shown
4. Use the output buttons to copy or save the result

Supported Palette Modes

Mode	Bits per pixel	Bytes per pixel
4-bit RBGG	4	0.5 (RBGG-RBGG)
8-bit Greyscale	8	1
8-bit RGB332	8	1
15-bit RGBA555	15	2
16-bit RGB565	16	2
16-bit BGR565	16	2
24-bit RGB	24	3
32-bit RGBA	32	4

Separate Bytes Example (RGBA, uint32_t)

Separate bytes OFF:

const uint32_t my_image[] = {
    0xFF0000FF, 0xFF0000FF, ...
};

Separate bytes ON:

const uint32_t my_image[] = {
    0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, ...
};

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Output

The 1-bit converter saves .h or .hpp header files containing a C array and a comment block with all conversion parameters.

The colour converter saves .h, .hpp, .c, or .txt files. A preview image can also be saved as PNG, BMP, or JPG.

Both tools copy output data to the clipboard automatically on save for quick pasting into an IDE.

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Configuration file

The configuration file is created on startup and populated with default values. The file is located at ~/.config/guardian_ltsm/guardian_ltsm.cfg on Linux systems.

Section	Setting	Type	Default	Note
Paths	input_dir	string	home directory	Default directory for open file dialogs
Paths	output_dir	string	home directory	Default directory for save file dialogs
Display	preview_width	int	160	Width of image preview boxes in pixels
Display	preview_height	int	160	Height of image preview boxes in pixels
Display	screen_resolution	string	1000x800	Size of the main application window on start up
Debug	debugOnOff	bool	0	Enable debug output to terminal

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Screenshots

1-Bit Converter — Image to Data

Colour Converter

4 bit colour (RBGG) palette preview

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See Also

Colossus_LTSM — Sister project. Converts TrueType fonts (.ttf) into C/C++ bitmap arrays and visualizes font data stored in C/C++ header files. Aimed at the same embedded systems audience.