BitPast

What's New

Version 4.6 lets you choose how a photo fills the screen and brings Per-Line palettes to the Apple IIgs. Version 4.5 brought better colors, disk images that load on real machines, and an app that stays responsive while it works.

whats_new.txt

4.6 - FIT AND ASPECT

Fit for every machine: Stretch, Contain (black bars), Cover (crop) or None (no scaling)
Aspect: allow for each machine's non-square pixels, so circles stay round
Drag the preview to choose which part of the picture shows

4.6 - APPLE IIGS

New SCB Mode for 256 colors: Per-Line lets every line pick the best of its 16 palettes
Palette editor changes are now saved in the file, in batch exports and on disk images

4.6 - FIXES

H-Flip and V-Flip now flip the saved file and disk images too, not just the preview
Apple II and IIgs results no longer depend on the attached screens

4.5 - BETTER COLORS

Smarter color selection for Atari 800, Atari ST, Amiga 500/1200, PC (EGA 64) and MSX Screen 5 - small details keep their color
Atari 800 Graphics 8 uses two shades of one hue, exactly like the real hardware
The same picture with the same settings always converts the same way

4.5 - DISK IMAGES

New: Spectrum +3 disk images (180 KB .dsk)
Fixed BBC Micro, TRS-80 CoCo, Amiga ADF, Atari ATR and ZX Spectrum TRD disks
Amstrad CPC files use the correct colors on a real CPC
Double-sided CoCo disks and DOS 2.5 for 130 KB Atari disks

4.5 - FASTER AND SMOOTHER

Conversions run in the background - the app stays responsive
A progress indicator shows while a new picture is calculated
Much faster PC 256-color conversion

One Photo, 15 Machines

The same photo, converted with each machine's default settings - exactly as BitPast saves it, shown on a 4:3 screen like the original hardware.

original.jpg

The original photo

Rose on the Apple II — **Apple II**Double Hi-Res, 16 colors

Rose on the Apple IIgs — **Apple IIgs**3200 colors, a palette per line

Rose on the Amiga 500 — **Amiga 500**32 of 4096 colors

Rose on the Amiga 1200 — **Amiga 1200**256 colors (AGA)

Rose on the Amstrad CPC — **Amstrad CPC**Mode 1, 4 of 27 colors

Rose on the Atari 800 — **Atari 800**Graphics 15, 4 of 128 colors

Rose on the Atari ST — **Atari ST**Low Res, 16 of 512 colors

Rose on the BBC Micro — **BBC Micro**Mode 2, 8 colors

Rose on the Commodore 64 — **Commodore 64**Multicolor, 16 colors

Rose on the MSX2 — **MSX2**Screen 5, 16 of 512 colors

Rose on the IBM PC — **IBM PC**VGA, 256 colors

Rose on the Commodore Plus/4 — **Plus/4**Hi-Res, 121-color TED palette

Rose on the TRS-80 Color Computer — **TRS-80 CoCo**PMODE 3, fixed 4-color set

Rose on the VIC-20 — **VIC-20**Hi-Res, custom characters

Rose on the ZX Spectrum — **ZX Spectrum**2 colors per 8x8 cell

Screenshots

Drop in your pictures, pick a machine, tune the look - and pick a theme that matches.

BitPast in the GS/OS theme converting a rose to Apple IIgs 3200 colors — **Apple IIgs in the GS/OS theme**Near-photographic 3200-color pictures, with a 16-color palette on every one of the 200 lines.

BitPast in the Apple II green phosphor theme with a Double Hi-Res conversion — **Apple II green phosphor**Double Hi-Res with b2d dithering and authentic NTSC palettes.

BitPast in the Commodore 64 theme with a Multicolor conversion of a fort by the sea — **Commodore 64 blue**Multicolor and Hi-Res, saved as Koala Painter or Art Studio files.

BitPast converting a red flowering tree to 256 Amiga AGA colors — **Amiga 1200, 256 colors**Standard, HAM6 and HAM8 modes, saved as IFF/ILBM - with dithering, contrast, filters, saturation and gamma.

Palette editor showing the line palettes of a 3200-color picture — **Palette editor**Fine-tune every line palette of a 3200-color picture, with undo and redo.

Create Disk Image window with an Amiga ADF disk selected — **Disk images for every machine**Put all your converted pictures on a disk image, ready for an emulator or real hardware.

Features

Everything you need to create authentic retro graphics.

🖥️

15 Classic Computers

Apple II and IIgs, Amiga 500 and 1200, Amstrad CPC, Atari 800 and ST, BBC Micro, C64, MSX, IBM PC, Plus/4, TRS-80 CoCo, VIC-20 and ZX Spectrum.

🌈

Real Palettes and Modes

Each machine's own colors, resolutions and limits - from Apple IIgs 3200 colors and Amiga HAM to Spectrum attribute cells and C64 multicolor.

🎯

Smart Color Selection

Colors are chosen to cover the whole picture, so small details keep their color even when a machine can only show a handful.

🖼️

Fit and Aspect

Stretch, letterbox, crop or keep the original size - and allow for each machine's non-square pixels so circles stay round.

⚙️

Fine-Tuning

15+ dithering algorithms, HE, CLAHE and SWAHE contrast, filters, color matching modes, saturation and gamma - with live preview.

💾

Native Files and Disks

Save .SHR, .3200, .IFF, .PI1, .KLA, .ART, .PRG, .SCR, .PCX, .SC5 and more, and put them on disk images for every machine.

🎨

Palette Editor

Edit the palettes of Apple IIgs pictures line by line, copy and paste palettes, with full undo and redo. Your changes go into the saved file.

📦

Batch Conversion

Drag in many pictures at once, lock settings per picture, and export them all - or straight onto a disk.

📺

Retro Themes

Work in the GS/OS look, Apple II green phosphor or Commodore 64 blue - or a clean modern interface.

Supported Systems

Modes and native file formats for every machine.

apple ii / iigs

Apple II: Double Hi-Res, Hi-Res, Lo-Res and Double Lo-Res (.BIN)
Apple IIgs: 3200 colors, 256 colors with Banded or Per-Line palettes, 320 and 640 modes (.SHR, .3200)

commodore

C64: Hi-Res, Multicolor and PETSCII (.ART, .KLA, .PRG)
VIC-20: Hi-Res and Low-Res (.PRG)
Plus/4: Hi-Res and Multicolor (.PRG)

amiga

Amiga 500: OCS/ECS up to 32 colors and HAM6 (.IFF)
Amiga 1200: AGA 256 colors and HAM8 (.IFF)

atari

Atari 800: Graphics 8, 9, 10, 11 and 15 (.GR8 to .GR15)
Atari ST: 16 of 512 colors, Low and High Res (.PI1 Degas)

british micros

ZX Spectrum: 256x192 with attribute cells (.SCR)
BBC Micro: Modes 0, 1, 2, 4 and 5
Amstrad CPC: Mode 0 and Mode 1 (.SCR)

pc / msx / coco

IBM PC: CGA, EGA, VGA and ANSI text modes (.PCX, .ANS)
MSX / MSX2: Screen 2, 5 and 8 (.SC2, .SC5, .SC8)
TRS-80 CoCo: PMODE 1-4 and CoCo 3 (.BIN, .CM3)

Disk Images

Create disk images for every supported machine.

disk_formats

Extension	Machine	Sizes
.po .2mg .hdv	Apple II / IIgs (ProDOS)	140 KB, 800 KB, 32 MB
.d64 .d71 .d81	C64, VIC-20, Plus/4	170 KB, 340 KB, 800 KB
.adf	Amiga 500 / 1200	880 KB, 1.76 MB
.atr	Atari 800 (DOS 2 / 2.5)	90 KB, 130 KB, 180 KB, 360 KB
.st	Atari ST	360 KB, 720 KB, 1.44 MB
.ssd .dsd	BBC Micro (DFS)	100 KB, 200 KB, 400 KB
.dsk	MSX	360 KB, 720 KB
.dsk	Amstrad CPC	180 KB, 360 KB
.trd .dsk	ZX Spectrum (TR-DOS, +3)	640 KB, 180 KB
.img	IBM PC	360 KB, 720 KB, 1.2 MB, 1.44 MB
.dsk	TRS-80 CoCo (RS-DOS)	180 KB, 360 KB

Get BitPast

Get it ready to run on the Mac App Store. Buying it is also a way to say thank you for my work - it makes me very happy and keeps the app growing.

Buy on App Store Download the Manual (PDF)

macOS 15.7 or later Apple Silicon or Intel Mac See also Retro Graphics Converter - view and convert original retro pictures