Image Preparation for Mega Drive Graphics

mega-drive-image-prep.md

Steps for Preparing an Image for Mega Drive Graphics

1. Pick an image with a 10:7 aspect ratio.
2. Resize it to the Mega Drive's native resolution.
3. Quantize the image to meet Mega Drive hardware limitations.

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Step 1: Picking an Image

The input image should have (approximately) a 10:7 aspect ratio, matching the Mega Drive's NTSC resolution of 320x224.

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Step 2: Resizing the Image

Resize the image using the following ImageMagick command:

# Adjust -gravity to control the focus area: center, north, south, east, west, etc.
magick input.png -filter Point -resize '320x224^' -gravity center -extent 320x224 -dither None -remap input.png output.png

This resizes the image to the Mega Drive's resolution using nearest neighbor interpolation (-filter Point) to preserve sharp edges and ensures the output matches the original palette without introducing new colors.

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Step 3: Quantizing the Image

Use the Tiled Palette Quantization with the following settings:

• Tile Width: 8
• Tile Height: 8
• Palettes: 4
• Colors per Palette: 16
• Bits per Channel: 3
• Fraction of Pixels: 0.10

Color Index Zero Behavior

Choose either:

• Shared Color
• Transparent Color

Dithering

• Disabled (recommended for cleaner output)
• Or Slow if dithering is desired, with Dither Weight set between 0.10 and 0.50 (depending on the level of dithering you prefer).

Dither Pattern

Select one that suits your aesthetic preferences.