zx-graphics-assetslisted

# ZX Spectrum graphics assets (images → .scr, sprites, UDGs) This skill converts images into the formats the ZX Spectrum actually uses, and explains the byte-level rules so the output is correct rather than sliced or mis-coloured. It bundles **runnable converters** — you don't hand-pack bytes. Two jobs: 1. **Full-screen images → `.scr`** (a 6912-byte loading screen). Use `scripts/png2scr.py`. 2. **Artwork → 8×8 cell data** (UDGs for BASIC, sprite tables for asm/C). Use `scripts/sprite_extract.py`. The hard parts are two facts about Spectrum video, both covered in depth in the references: the pixel display file uses a **non-linear address layout**, and colour is stored **per 8×8 cell with only two colours each** (colour clash). This skill stays consistent with the screen/attribute model documented in the `zx-spectrum-basic` skill's `references/graphics.md` — read that for the BASIC side (PLOT/DRAW, UDGs, ATTR). ## The .scr format in one screen A `.scr` is a raw dump of screen memory, **6912 bytes**: - **6144 bytes** pixel display file (loads to `0x4000`) — 1 bit/pixel, 256×192, bit set = ink. **Non-linear** layout (see below). - **768 bytes** attribute file (loads to `0x5800`) — 1 byte per 8×8 cell, 32×24, linear. **Non-linear pixel addressing.** For pixel `(x, y)`, `x` 0–255, `y` 0–191, the byte offset inside the 6144-byte region and the bit within it are: ``` third = y >> 6 # which vertical third: 0, 1, 2 char_row = (y >> 3) & 7 # char