Add double bed jacquard punchcard generation

.gitignore

@@ -0,0 +1 @@
+__pycache__/

QUICKSTART.md

@@ -78,6 +78,24 @@ find . -name "*.pcx" | python3 punchcard-generator.py --stitches 24 --layout mot
 - `-d ./output` preserve subfolder structure in output folder
 - `--threshold 220` change punch sensitivity
 - `--invert` invert pixel-to-punch behavior
+- `--jacquard {none,doublebed,birdseye,tuck}` double bed jacquard mode
+
+## 6) Double bed jacquard
+
+For double bed jacquard knitting the punchcard rows are doubled — each design row becomes two punchcard rows (pattern row + backing row). Three backing styles are available:
+
+```bash
+# Solid/full-jacquard backing (all stitches punched on backing row)
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard doublebed
+
+# Bird's eye backing (alternating checkerboard on backing row)
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard birdseye
+
+# Tuck-stitch backing (inverse of pattern on backing row)
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard tuck
+```
+
+> A 6-row design with `--jacquard doublebed` produces a 12-row card.
 
 ## Troubleshooting 🔧
 

README.md

@@ -17,6 +17,7 @@ This uttility generates SVG files, usable in most diecutting machines, for punch
 - 🧵 Supports 12-stitch and 24-stitch card widths
 - 🔁 Layout modes: `auto`, `motif`, and `repeat`
 - 📏 Vertical repeats for longer pattern runs
+- 🧶 Double bed jacquard modes: `doublebed`, `birdseye`, and `tuck`
 - 🧪 Batch processing from shell globs and stdin
 - ⚙️ Threshold and inversion controls for image-to-punch mapping
 
@@ -87,6 +88,7 @@ find . -name "*.pcx" | python3 punchcard-generator.py --stitches 24 --layout mot
 - `--stitches {12,24}` card width (default `24`)
 - `--layout {auto,motif,repeat}` layout mode (default `auto`)
 - `--repeat-height N` vertical repeats (default `1`)
+- `--jacquard {none,doublebed,birdseye,tuck}` double bed jacquard mode (default `none`)
 - `--threshold 0-255` image threshold (default `255`)
 - `--invert` invert punched and non-punched spaces on the card
 - `--hole-ratio 0-1` hole size ratio (default `0.55`)
@@ -97,6 +99,23 @@ find . -name "*.pcx" | python3 punchcard-generator.py --stitches 24 --layout mot
 - `repeat`: tiles design across width (design width must divide by card width)
 - `auto`: picks `motif` or `repeat` based on width compatibility
 
+## 🧶 Double Bed Jacquard
+
+Double bed jacquard uses both the main bed and the ribber to create a two-layer fabric. Each design row is split into two punchcard rows: the pattern row (colour selection) and a backing row. Use `--jacquard` to enable this mode:
+
+- `none` (default): standard 1:1 punchcard
+- `doublebed`: solid/full-jacquard backing — every stitch punched on the backing row
+- `birdseye`: bird's eye backing — alternating checkerboard pattern on the backing row
+- `tuck`: tuck-stitch backing — inverse of the pattern row on the backing row
+
+```bash
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard doublebed
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard birdseye
+python3 punchcard-generator.py design.png 24 motif 6 --jacquard tuck
+```
+
+> **Note:** Double bed jacquard doubles the number of rows on the card. A 6-row motif with `--jacquard doublebed` produces a 12-row card.
+
 ## 🤝 Contributing
 
 Ideas, bug reports, and PRs are welcome.

punchcard-generator.py

@@ -184,6 +184,45 @@ def compose_card_rows(rows, card_stitches, card_layout, repeat_height):
     raise ValueError(f"Unsupported card layout '{layout}'")
 
 
+def build_double_bed_rows(rows, backing="doublebed"):
+    """Transform card rows for double bed jacquard knitting.
+
+    Each pattern row is doubled into two punchcard rows:
+      - Row 1 (odd pass):  the original pattern row (selects needles for colour A)
+      - Row 2 (even pass): a backing row whose style is chosen by ``backing``
+
+    Backing modes
+    -------------
+    doublebed : every stitch punched – solid / full-jacquard backing
+    birdseye  : alternating x-/checkerboard backing (bird's eye)
+    tuck      : inverse of the pattern row (tuck-stitch backing)
+    """
+    if not rows:
+        return rows
+
+    width = len(rows[0])
+    result = []
+
+    for i, row in enumerate(rows):
+        result.append(row)
+
+        if backing == "doublebed":
+            result.append("x" * width)
+        elif backing == "birdseye":
+            # Checkerboard: phase shifts by 1 each pair so the backing forms a
+            # diagonal bird's eye grid across the fabric.
+            offset = i % 2
+            backing_row = "".join("x" if (j + offset) % 2 == 0 else "-" for j in range(width))
+            result.append(backing_row)
+        elif backing == "tuck":
+            tuck_row = "".join("-" if ch == "x" else "x" for ch in row)
+            result.append(tuck_row)
+        else:
+            raise ValueError(f"Unsupported double bed backing mode: '{backing}'")
+
+    return result
+
+
 def write_brother_style_svg(
     path,
     rows,
@@ -326,6 +365,7 @@ def generate_punchcard(
     card_stitches=None,
     card_layout="auto",
     card_repeat_height=1,
+    jacquard="none",
 ):
     img = open_flattened_rgb_image(input_path)
     rows, width_cells, height_cells = build_punch_rows(img, threshold=threshold, invert=invert)
@@ -346,6 +386,9 @@ def generate_punchcard(
         )
         output_width = card_stitches
 
+    if jacquard != "none":
+        output_rows = build_double_bed_rows(output_rows, backing=jacquard)
+
     if punchcard_mode in ("text", "both"):
         txt_path = output_base + ".punch.txt"
         write_punch_text(txt_path, output_rows)
@@ -373,7 +416,8 @@ def generate_punchcard(
         print(f"Created: {svg_path}")
 
     if layout_used is not None:
-        print(f"Card layout: {layout_used}, width: {card_stitches}, rows: {len(output_rows)}")
+        jacquard_info = f", jacquard: {jacquard}" if jacquard != "none" else ""
+        print(f"Card layout: {layout_used}, width: {card_stitches}, rows: {len(output_rows)}{jacquard_info}")
 
 
 def process_file(
@@ -389,6 +433,7 @@ def process_file(
     stitches=24,
     layout="auto",
     repeat_height=1,
+    jacquard="none",
 ):
     input_path = input_path.strip()
     if not input_path or not os.path.exists(input_path):
@@ -416,6 +461,7 @@ def process_file(
             card_stitches=stitches,
             card_layout=layout,
             card_repeat_height=repeat_height,
+            jacquard=jacquard,
         )
     except Exception as e:
         print(f"Error on {input_path}: {e}", file=sys.stderr)
@@ -483,6 +529,19 @@ def process_file(
         default=1,
         help="Number of vertical repeats for card pattern. Default: 1.",
     )
+    parser.add_argument(
+        "--jacquard",
+        choices=["none", "doublebed", "birdseye", "tuck"],
+        default="none",
+        help=(
+            "Double bed jacquard mode. Each pattern row is doubled: the original row"
+            " followed by a backing row. "
+            "none: standard 1:1 card (default). "
+            "doublebed: full/solid backing (all stitches punched). "
+            "birdseye: alternating checkerboard backing (bird's eye). "
+            "tuck: inverse of the pattern row (tuck-stitch backing)."
+        ),
+    )
     parser.add_argument("-help", action="help", help="Show this help message and exit.")
 
     parser.add_argument(
@@ -561,6 +620,7 @@ def process_file(
                 stitches=stitches,
                 layout=layout,
                 repeat_height=repeat_height,
+                jacquard=args.jacquard,
             )
 
     # 2. Process files passed via pipe (e.g., find . -name '*.pcx' | punchcard)
@@ -579,6 +639,7 @@ def process_file(
                 stitches=stitches,
                 layout=layout,
                 repeat_height=repeat_height,
+                jacquard=args.jacquard,
             )
 
     # 3. If no input was provided via either method, show the help