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Overview

DevCPC includes powerful graphics conversion tools that automatically convert modern PNG images into Amstrad CPC formats. The tools handle palette conversion, format encoding, and optimization.

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Components

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png2asm.py

Converts PNG images to ASM sprite data:
  • Input: PNG images (any size)
  • Output: Z80 assembly sprite data
  • Features: Automatic palette detection, mode validation, label generation

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img.py (ABASM)

Converts PNG to SCN screen files:
  • Input: PNG images (160×200, 320×200, or 640×200)
  • Output: 16KB SCN screen files
  • Features: Full-screen conversion with palette info

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Pillow (PIL)

Python Imaging Library for image processing: 
pip3 install Pillow

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Sprite Conversion

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Configuration

Enable sprite conversion in devcpc.conf:
devcpc.conf
# Sprite conversion settings
SPRITES_PATH="assets/sprites"
SPRITES_OUT_FILE="ASM/sprites.asm"
MODE=0
SPRITES_TOLERANCE=8
SPRITES_TRANSPARENT_INK=""

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Directory Structure

my-game/
├── assets/
│   └── sprites/
│       ├── player.png      # 16×16 sprite
│       ├── enemies/
│       │   ├── enemy1.png
│       │   └── enemy2.png
│       └── tiles/
│           ├── tile1.png
│           └── tile2.png
└── ASM/
    └── sprites.asm         # Generated

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PNG Requirements

  • Resolution: 160×200 max
  • Sprite width: Multiple of 2 pixels
  • Colors: Up to 16 colors from CPC palette
  • Encoding: 2 pixels per byte (4 bits each)

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CPC Palette

The converter maps RGB colors to the 27-color CPC palette:
INKRGBName
0(0,0,0)Black
1(0,0,128)Blue
2(0,0,255)Bright Blue
6(255,0,0)Red
24(255,255,0)Yellow
26(255,255,255)White
See full palette

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Tolerance

The SPRITES_TOLERANCE setting controls color matching: 
# Exact match only (RGB must match exactly)
SPRITES_TOLERANCE=0

# Recommended (allows small variations)
SPRITES_TOLERANCE=8

# Always find closest color
SPRITES_TOLERANCE=-1

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Generated ASM Format

ASM/sprites.asm
; MODE 0
; Generated by png2asm.py

PLAYER
;------ BEGIN IMAGE --------
  db 2      ; width in bytes
  db 16     ; height in pixels
  db 0, 0
  db 85, 85
  db 170, 170
  ; ... sprite data
;------ END IMAGE --------
  ; Palette detected:
  ; INK 0,0   (Black)
  ; INK 1,24  (Yellow)
  ; INK 2,6   (Red)

ENEMY1
;------ BEGIN IMAGE --------
  db 2
  db 16
  ; ... sprite data
;------ END IMAGE --------

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Using Sprites in Code

include "sprites.asm"

; Draw player sprite
ld hl, PLAYER
call |PSPRITE

; Draw enemy sprite
ld hl, ENEMY1
call |PSPRITE

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Screen Conversion

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Configuration

Enable screen conversion in devcpc.conf:
devcpc.conf
# Screen conversion settings
LOADER_SCREEN="assets/screen"
MODE=0

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Directory Structure

my-game/
├── assets/
│   └── screen/
│       ├── title.png       # 160×200 Mode 0
│       └── loading.png     # 160×200 Mode 0
├── obj/
│   ├── title.scn           # Generated
│   ├── title.scn.info      # Palette info
│   ├── loading.scn
│   └── loading.scn.info
└── dist/
    └── my-game.dsk         # SCN files included

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PNG Requirements

Screen PNGs must be exact dimensions:
  • Mode 0: 160×200 pixels (16 colors)
  • Mode 1: 320×200 pixels (4 colors)
  • Mode 2: 640×200 pixels (2 colors)

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Generated Files

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SCN File

title.scn       # 16384 bytes (16 KB)
                # Direct screen memory dump
                # Load to &C000

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Info File

title.scn.info  # Palette information
Example info contents: 
FILE: title.scn
WIDTH: 160
HEIGHT: 200
MODE: 0
PALETTE COLORS: 8

FW              HW              RGB
0               0x14            (0, 0, 0)
24              0x0A            (255, 255, 0)
6               0x04            (255, 0, 0)

; ASM HW palette
db 0x14, 0x0A, 0x04

' BASIC palette
INK 0,0: INK 1,24: INK 2,6

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Loading Screens

From BASIC: 
10 MODE 0
20 LOAD"TITLE.SCN",&C000
30 INK 0,0: INK 1,24: INK 2,6
40 PAUSE 100
From ASM: 
; Load screen from binary
ld hl, title_scn
ld de, &C000
ld bc, 16384
ldir

; Set palette (from .info file)
ld bc, &7F00
ld a, 0
out (c), a
ld bc, &7F01
ld a, &14    ; INK 0 = Black
out (c), a
; ... continue for all inks

title_scn:
incbin "title.scn"

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Manual Conversion

Run converters manually:

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Sprites

python3 ~/.DevCPC/tools/8bp-graphics-converter/png2asm.py \
    --mode 0 \
    --tolerance 8 \
    --input assets/sprites \
    --output ASM/sprites.asm

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Screens

python3 ~/.DevCPC/tools/abasm/src/img.py \
    --input assets/screen/title.png \
    --output obj/title.scn \
    --mode 0

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Creating Graphics

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GIMP Workflow

1

Create image

  • File → New
  • Set dimensions (e.g., 160×200 for Mode 0)
  • Image → Mode → RGB color
2

Use CPC palette

Import CPC palette:
  • Windows → Dockable Dialogs → Palettes
  • Import CPC.gpl palette file
  • Use Colors from palette only
3

Draw graphics

  • Use Pencil tool (hard edges)
  • Zoom in for pixel-perfect editing
  • Use only colors from CPC palette
4

Export

  • File → Export As
  • Choose PNG format
  • Save to assets/sprites/ or assets/screen/

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Aseprite Workflow

For sprite animation:
  1. Create sprite at correct size (e.g., 16×16)
  2. Set palette to CPC colors
  3. Draw frames
  4. Export each frame as separate PNG
  5. Place in assets/sprites/ directory

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Troubleshooting

pip3 install Pillow
python3 -c "import PIL; print('Pillow OK')"
Sprite width must be:
  • Mode 0: multiple of 2 (2, 4, 6, 8, 10, 12, 14, 16…)
  • Mode 1: multiple of 4 (4, 8, 12, 16, 20…)
  • Mode 2: multiple of 8 (8, 16, 24, 32…)
Resize your PNG to match requirements.
Increase tolerance:
SPRITES_TOLERANCE=16
Or use automatic:
SPRITES_TOLERANCE=-1
Reduce colors in your image:
  • Mode 0: max 16 colors
  • Mode 1: max 4 colors
  • Mode 2: max 2 colors
Use GIMP or Aseprite to reduce palette.

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Resources

Graphics Guide

Complete graphics conversion guide

Loading Screens Recipe

Create and load screen graphics

Sprite Animation Recipe

Animate sprites in your games

Configuration

Graphics configuration reference

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Credits

Build docs developers (and LLMs) love

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