Best Practices

Tips and techniques for getting reliable, high-quality pixel art from LLMs.

Prompt Structure

Be Explicit About Format

LLMs work best with clear, specific instructions. Always include:

1. Dimensions: "16x16 pixels" not just "small"
2. Color count: "using 4-8 colors"
3. Style reference: "SNES-era" or "Game Boy style"
4. Output format: "in pixelsrc JSONL format"

Good Prompt Example

Create a 16x16 pixel art treasure chest in pixelsrc format. Use a warm brown wood color, gold trim, and a dark shadow. Include a keyhole detail. Use semantic token names like {wood}, {gold}, {shadow}. Keep the palette under 8 colors.

Bad Prompt Example

Make me a chest

Token Naming

Use Semantic Names

Semantic token names produce better, more editable output:

Consistent Naming Patterns

For related colors, use suffixes:

{skin}        - base color
{skin_light}  - highlight
{skin_dark}   - shadow

For body parts:

{hair}
{hair_highlight}
{eye}
{eye_pupil}

Color Palettes

Limit Colors

Different color counts suit different styles:

• 4 colors: Game Boy, minimalist
• 8 colors: NES, clean retro
• 16 colors: SNES, detailed retro
• 32+ colors: Modern pixel art

Ask for specific counts: "use exactly 6 colors"

Request Harmony

"Use a complementary color scheme with blue and orange"

"Use an analogous palette of warm earth tones"

"Match the NES palette limitations"

Include Alpha

Always request transparency handling:

"Use {_} with #00000000 for transparent pixels"

Multi-Sprite Workflows

Shared Palettes

When generating multiple related sprites, define the palette first:

"First, create a palette called 'hero_colors' with skin, hair, shirt, pants, and outline colors. Then create 4 sprite frames using that palette."

Animation Frames

For animations, be specific about frame differences:

"Create a 4-frame walk cycle:

• Frame 1: left foot forward
• Frame 2: feet together
• Frame 3: right foot forward
• Frame 4: feet together Keep the body consistent across frames, only animate the legs."

Tileset Consistency

For tilesets, establish rules:

"Create a 4-tile grass tileset that tiles seamlessly. Use the same 3 shades of green across all tiles. Ensure edges match when tiles are placed adjacent."

Large Images with Tiling

For images larger than 32x32, use composition with cell_size:

"Create a 64x64 landscape scene. First generate four 32x32 tiles: sky_left, sky_right, ground_left, ground_right. Then compose them with cell_size [32, 32]."

Example composition:

{"type": "composition", "name": "landscape", "size": [64, 64], "cell_size": [32, 32],
  "sprites": {"A": "sky_left", "B": "sky_right", "C": "ground_left", "D": "ground_right"},
  "layers": [{"map": ["AB", "CD"]}]}

Color Variants

Use variants to recolor existing sprites without regenerating:

"Create a hero sprite, then create a variant called 'hero_fire' with red hair instead of brown"

{"type": "variant", "name": "hero_fire", "base": "hero", "palette": {"{hair}": "#FF4400"}}

Iteration Strategies

Silhouette First

Before adding detail, nail the outline. A good silhouette is recognizable when filled solid.

The Mushroom Principle: Most organic forms can be built from 3 basic shapes:

• Circle - head/cranium
• Rectangle - torso/mid-section
• Triangle/Polygon - tapers (jaw, legs)

Workflow:

1. Define outline with 2-3 basic shapes
2. Adjust proportions until shape reads correctly
3. Add asymmetry for 3/4 view (shift shapes, angle triangles)
4. Only then add internal detail, shading, features

If you can't make the silhouette work with 3 shapes, the problem is proportions, not detail.

Start Simple, Add Detail

1. Generate basic shape
2. Add colors/shading
3. Refine details
4. Create variations

Ask for Variations

"Create 3 color variations of this sprite:

1. Original colors
2. Night version (darker, bluer)
3. Autumn version (warmer oranges)"

Refine Incrementally

"The sword looks good, but make the blade 2 pixels longer and add a shine highlight on the edge"

Quality Checklist

Before using generated sprites, verify:

• Valid JSON (parseable)
• Correct dimensions match request
• All rows have same token count
• Transparency token defined
• Colors are valid hex format
• Token names are semantic
• Renders correctly with pxl render
• No magenta (error color) in output

# Quick validation
pxl render generated.pxl --strict

# Format for consistency
pxl fmt generated.pxl

# If it renders without errors, you're good

Model-Specific Tips

Claude

• Excellent at following complex format rules
• Include the full system prompt for best results
• Can generate and explain in same response
• Handles multi-step workflows well

GPT-4

• Strong at visual concepts
• May need reminding about JSON syntax
• Use "System" message for format instructions
• Good at creative variations

Local Models

• Keep prompts simpler
• Provide more examples
• May need multiple attempts
• Consider fine-tuning for pixelsrc format

Known Rendering Limitations

Some shape combinations can cause rendering artifacts. Keep these in mind:

Safe patterns:

• 3-4 simple shapes (circle, rect, polygon with 3-5 vertices)
• union of simple shapes

Risky patterns:

• 5+ overlapping regions with same color
• Single polygon with 6+ vertices

When in doubt, keep it simple. If you hit artifacts, reduce complexity.