Graphics Conversion

Overview

DevCPC includes automatic conversion tools for graphics:

Sprites: PNG → ASM format for use in games
Loading Screens: PNG → SCN format for full-screen images

Both use the CPC color palette and are automatically processed during devcpc build.

Sprite Conversion (PNG → ASM)

Configuration

Add to your devcpc.conf:

# Sprite conversion settings
SPRITES_PATH="assets/sprites"     # Where PNG files are located
SPRITES_OUT_FILE="ASM/sprites.asm" # Output ASM file
MODE=0                              # CPC mode (0, 1, or 2)
SPRITES_TOLERANCE=8                 # RGB tolerance
SPRITES_TRANSPARENT_INK=""          # Optional: INK for transparency

CPC Modes

Mode	Colors	Pixels/byte	Bits/pixel	Resolution
0	16	2	4	160x200
1	4	4	2	320x200
2	2	8	1	640x200

Directory Structure

my-game/
├── assets/
│   └── sprites/           # Your PNG files (recursive search)
│       ├── player.png
│       ├── enemies/
│       │   ├── alien1.png
│       │   └── alien2.png
│       └── tiles/
│           ├── wall.png
│           └── floor.png
│
└── ASM/
    └── sprites.asm       # Generated automatically

Usage

# 1. Place PNG files in assets/sprites/
# 2. Configure SPRITES_PATH in devcpc.conf
# 3. Build project
devcpc build

DevCPC automatically:

Searches recursively for PNG files
Converts to CPC palette
Generates ASM with sprite data
Includes palette information

Build Output

═══════════════════════════════════════
  Convertir Sprites PNG a ASM
═══════════════════════════════════════

ℹ Ruta sprites:    assets/sprites
ℹ Modo CPC:        0
ℹ Archivo salida:  ASM/sprites.asm
ℹ Tolerancia RGB:  8

ℹ Ejecutando png2asm.py...

OK: ASM/sprites.asm
PNGs encontrados: 3  | Convertidos OK: 3  | Errores: 0

Resumen:
PNG           Label      Size(px)  Bytes/line  Colors  Fallback  Status
player.png    player     16x16     2           4       no        OK
enemy1.png    enemy1     16x16     2           3       no        OK
tile1.png     tile1      8x8       1           2       no        OK

✓ Sprites convertidos exitosamente

Generated ASM Format

; MODE 0

PLAYER
;------ BEGIN IMAGE --------
  db 2     ; width in bytes
  db 16    ; height in pixels
  db 0, 0
  db 0, 0
  db 85, 85
  db 170, 170
  ; ... more bytes
;------ END IMAGE --------
  ; Palette (PEN -> INK) detected in PNG
  ; INK 0,0
  ; INK 1,24
  ; INK 2,6

ENEMY1
;------ BEGIN IMAGE --------
  db 2
  db 16
  ; ... sprite data
;------ END IMAGE --------
  ; INK 0,0
  ; INK 1,2

Using Sprites in Code

; Include generated sprites
include "sprites.asm"

; Draw sprites with 8BP
ld hl, PLAYER
call |PSPRITE

ld hl, ENEMY1
call |PSPRITE

CPC Color Palette

The Amstrad CPC has 27 hardware colors (INK 0-26):

INK 0  = Black (0,0,0)
INK 1  = Dark Blue (0,0,128)
INK 2  = Blue (0,0,255)
INK 3  = Dark Red (128,0,0)
INK 4  = Dark Magenta (128,0,128)
INK 5  = Magenta (128,0,255)
INK 6  = Red (255,0,0)
INK 7  = Pink (255,0,128)
INK 8  = Light Pink (255,0,255)
INK 9  = Dark Green (0,128,0)
INK 10 = Dark Cyan (0,128,128)
INK 11 = Cyan (0,128,255)
INK 12 = Dark Yellow (128,128,0)
INK 13 = Gray (128,128,128)
INK 14 = Pastel Blue (128,128,255)
INK 15 = Orange (255,128,0)
INK 16 = Pastel Pink (255,128,128)
INK 17 = Purple (255,128,255)
INK 18 = Green (0,255,0)
INK 19 = Sea Green (0,255,128)
INK 20 = Light Cyan (0,255,255)
INK 21 = Yellow-Green (128,255,0)
INK 22 = Pastel Green (128,255,128)
INK 23 = Pastel Cyan (128,255,255)
INK 24 = Yellow (255,255,0)
INK 25 = Pastel Yellow (255,255,128)
INK 26 = White (255,255,255)

Tolerance Settings

Tolerance controls how closely PNG colors must match the CPC palette:

# Exact match only (strict)
SPRITES_TOLERANCE=0

# Recommended (allows small variations)
SPRITES_TOLERANCE=8

# Automatic (always finds closest color)
SPRITES_TOLERANCE=-1

Transparency

Define an INK for transparent pixels (alpha=0):

# Transparent pixels become INK 0 (black)
SPRITES_TRANSPARENT_INK=0

# Transparent pixels become INK 16 (pastel pink)
SPRITES_TRANSPARENT_INK=16

Loading Screen Conversion (PNG → SCN)

Configuration

Add to your devcpc.conf:

# Screen conversion settings
LOADER_SCREEN="assets/screen"  # Where PNG screens are located
MODE=0                          # CPC mode (0, 1, or 2)

Screen Requirements

PNG files must match the CPC mode resolution:

Mode	Resolution	Colors	Use Case
0	160×200	16	Title screens, menus
1	320×200	4	High-res graphics
2	640×200	2	Text screens

Directory Structure

my-game/
├── assets/
│   └── screen/            # Your PNG screens
│       ├── title.png      # 160x200 (Mode 0)
│       ├── loading.png
│       └── credits.png
│
├── obj/                   # Generated by build
│   ├── title.scn         # 16KB screen file
│   ├── title.scn.info    # Palette info
│   ├── loading.scn
│   └── loading.scn.info
│
└── dist/
    └── my-game.dsk       # SCN files included

Usage

# 1. Create PNG screens (exact resolution required)
# 2. Place in assets/screen/
# 3. Configure LOADER_SCREEN in devcpc.conf
# 4. Build
devcpc build

Build Output

═══════════════════════════════════════
  Convertir Pantallas de Carga
═══════════════════════════════════════

ℹ Ruta:  assets/screen
ℹ Modo:  0 (160x200, 16 colores)

→ Convirtiendo title.png...
✓ title.scn generado (16384 bytes)

→ Convirtiendo loading.png...
✓ loading.scn generado (16384 bytes)

✓ 2 pantalla(s) convertida(s)

→ Añadiendo pantallas al DSK...

ℹ   title.scn
ℹ   loading.scn
✓ 2 pantalla(s) añadida(s) al DSK

SCN Info Files

Each screen generates a .scn.info file with palette data:

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

// C palette
hwpal = { 0x14, 0x0A, 0x04 }

Using Screens from BASIC

REM Load title screen
MODE 0
LOAD"TITLE.SCN",&C000
REM Set palette (from .info file)
INK 0,0: INK 1,24: INK 2,6
PAUSE 200

Using Screens from ASM

; Load screen to video memory
ld hl, title_scn
ld de, &C000
ld bc, 16384
ldir

; Set hardware palette
ld bc, &7F00
ld a, 0
out (c), a
ld bc, &7F01
ld a, &14    ; INK 0 = Black
out (c), a
; ... more INKs

title_scn:
incbin "title.scn"

PNG Requirements

Sprite PNGs

Width constraints:

Mode 0: Multiple of 2 pixels (2, 4, 6, 8, 10, 12, 14, 16…)
Mode 1: Multiple of 4 pixels (4, 8, 12, 16, 20…)
Mode 2: Multiple of 8 pixels (8, 16, 24, 32…)

Height: Any value (no constraint) Colors:

Mode 0: Maximum 16 colors
Mode 1: Maximum 4 colors
Mode 2: Maximum 2 colors

Screen PNGs

Resolution (exact):

Mode 0: 160×200 pixels
Mode 1: 320×200 pixels
Mode 2: 640×200 pixels

Colors: Same as sprite limits File size: All generate 16KB SCN files

Complete Example

Project Configuration

# devcpc.conf
PROJECT_NAME="space-game"
BUILD_LEVEL=0

# Graphics conversion
SPRITES_PATH="assets/sprites"
SPRITES_OUT_FILE="ASM/sprites.asm"
LOADER_SCREEN="assets/screen"
MODE=0
SPRITES_TOLERANCE=8

Create Graphics

# Create directories
mkdir -p assets/sprites
mkdir -p assets/screen

# Add your PNG files
# sprites: 16x16, 16 colors max
# screens: 160x200, 16 colors max

Build and Test

# Build everything
devcpc build

# Files generated:
# - ASM/sprites.asm (sprite data)
# - obj/title.scn (screen file)
# - obj/title.scn.info (palette)
# - dist/space-game.dsk (all included)

# Test in emulator
devcpc run

BASIC Loader Example

MODE 0
REM Load title screen
LOAD"TITLE.SCN",&C000
INK 0,0: INK 1,24: INK 2,6
PAUSE 200
REM Load 8BP with sprites
MEMORY 23599
LOAD"8BP0.BIN"
CALL &6B78

Troubleshooting

Common Errors

“Pillow no instalado”

pip3 install Pillow

“ancho no divisible”

Mode 0: Width must be even (2, 4, 6…)
Mode 1: Width must be ×4 (4, 8, 12…)
Mode 2: Width must be ×8 (8, 16, 24…)

“usa X INKs pero MODE permite Y”

Reduce colors in your PNG
Use a mode with more colors
Mode 0 = 16, Mode 1 = 4, Mode 2 = 2

“Color no coincide con paleta CPC”

Increase tolerance: SPRITES_TOLERANCE=16
Use automatic: SPRITES_TOLERANCE=-1
Adjust PNG colors to CPC palette

“Resolución incorrecta”

Mode 0: Must be exactly 160×200
Mode 1: Must be exactly 320×200
Mode 2: Must be exactly 640×200

Best Practices

Use CPC colors - Design with the 27-color palette
Test tolerance - Start with 8, adjust if needed
Organize sprites - Use subdirectories for categories
Check .info files - Verify palettes before coding
Validate early - Run devcpc build frequently

Sprites vs Screens Comparison

Feature	Sprites (ASM)	Screens (SCN)
Format	ASM source code	Binary data
Size	Variable	16KB (fixed)
Usage	Game graphics	Full screens
Load address	Any	0xC000 only
Included in	Compiled binary	DSK as file
PNG size	Any width (aligned)	Exact resolution
Output	One ASM file	Multiple SCN files

Getting Started

Core Concepts

Guides

Advanced

Tools

​Overview

​Sprite Conversion (PNG → ASM)

​Configuration

​CPC Modes

​Directory Structure

​Usage

​Build Output

​Generated ASM Format

​Using Sprites in Code

​CPC Color Palette

​Tolerance Settings

​Transparency

​Loading Screen Conversion (PNG → SCN)

​Configuration

​Screen Requirements

​Directory Structure

​Usage

​Build Output

​SCN Info Files

​Using Screens from BASIC

​Using Screens from ASM

​PNG Requirements

​Sprite PNGs

​Screen PNGs

​Complete Example

​Project Configuration

​Create Graphics

​Build and Test

​BASIC Loader Example

​Troubleshooting

​Common Errors

​Best Practices

​Sprites vs Screens Comparison

​See Also

Build docs developers (and LLMs) love

Overview

Sprite Conversion (PNG → ASM)

Configuration

CPC Modes

Directory Structure

Usage

Build Output

Generated ASM Format

Using Sprites in Code

CPC Color Palette

Tolerance Settings

Transparency

Loading Screen Conversion (PNG → SCN)

Configuration

Screen Requirements

Directory Structure

Usage

Build Output

SCN Info Files

Using Screens from BASIC

Using Screens from ASM

PNG Requirements

Sprite PNGs

Screen PNGs

Complete Example

Project Configuration

Create Graphics

Build and Test

BASIC Loader Example

Troubleshooting

Common Errors

Best Practices

Sprites vs Screens Comparison

See Also