BitPast

About BitPast

BitPast is a modern, native macOS application for converting images into authentic Apple II and Apple IIgs graphic formats. It acts as a powerful GUI wrapper around the legendary b2d tool by Bill Buckels for 8-bit systems, while utilizing a custom-built native Swift engine for 16-bit Apple IIgs graphics.

Key Features

Everything you need to create authentic retro graphics

🖥️

Modern macOS Interface

Drag & drop multiple images directly from Finder or the web. Batch processing with grid browser and live preview with real-time adjustments.

🎨

Powerful Conversion

Powered by b2d for Apple II (8-bit) and native Swift engine for Apple IIgs (16-bit) with advanced Median Cut Quantization.

🔍

Zoom & Pan

Inspect every single pixel with a high-performance zoomable preview and real-time rendering.

⚙️

Fine-Tuning Control

Extensive dithering algorithms (Floyd-Steinberg, Atkinson, Jarvis-Judice-Ninke, Stucki, Burkes, Ordered), crosshatch threshold, color bleed reduction.

🌈

3200 Color Mode

Uses Median Cut Quantization and intelligent scanline clustering for near-photorealistic images with all 16 palettes simultaneously.

💾

Flexible Exports

Export as modern formats (PNG, JPG, GIF, TIFF) or native binaries (.BIN, .SHR). Create bootable ProDOS disk images directly from the app.

Supported Graphics Formats

Convert graphics for Apple II and IIgs systems

🍏 Apple II (8-Bit)

DHGR (Double Hi-Res) 140×192 (16 colors) or 560×192 (Monochrome)

HGR (Hi-Res) 280×192 6 colors

LGR / DLGR Lo-Res and Double Lo-Res Block graphics

🌈 Apple IIgs (16-Bit)

3200 Mode (Smart Scanlines) 320×200 All 16 palettes simultaneously

Standard Mode 320×200 (16 colors) 640×200 (4 colors)

Super Hi-Res (SHR) Full 12-bit RGB 4096 color space

💾 Export Formats

Modern Preview PNG, JPG, GIF, TIFF For web use

Native Binaries .BIN (Apple II) .SHR (Apple IIgs)

ProDOS Disk Images .PO, .2MG, .HDV Bootable disks

Screenshots

See the app in action

Apple II Double Hi-Res Mode

Convert modern images to authentic Apple II DHGR format with advanced dithering algorithms. Live preview shows exactly how your image will look on vintage hardware.

Apple IIgs 3200 Color Mode

Utilize all 16 palettes simultaneously for near-photorealistic results. Smart scanline clustering and Median Cut Quantization deliver stunning quality.

Technical Details

BitPast is built with Swift and SwiftUI for macOS. The frontend uses SwiftUI with Grid Views, HSplitView, and Combine for debounced live previews. For Apple II (8-bit), it uses the b2d tool (modified build with struct packing fixes for modern macOS ARM64/x86_64). For Apple IIgs (16-bit), it features a native Swift implementation using Median Cut algorithm and Euclidean distance scanline clustering. Disk operations are handled via integrated wrapper for cadius by BrutalDeluxe to manage ProDOS volumes.