dapple

Terminal-centric development is now mainstream. Claude Code runs in your terminal. AI assistants stream their work as text. Developers SSH into remote machines, pair with tmux, and live in the command line. In this world, there's a gap: we want to see graphics without leaving the terminal.

dapple is a unified terminal graphics library. One Canvas API, multiple renderers: braille, quadrants, sextants, ASCII, sixel, kitty, and fingerprint. Choose the renderer that matches your terminal's capabilities and your visual needs.

Why a Unified Library?

Terminal graphics tools are fragmented. One library does braille. Another does quadrant blocks. A third handles sixel. Each has its own API, its own conventions.

dapple unifies these approaches:

• Single Canvas class - Load your bitmap once, output anywhere
• Pluggable renderers - Switch formats with one line: canvas.out(braille) or canvas.out(quadrants)
• Consistent options - Same preprocessing, same color modes, predictable behavior
• Stream-based output - Write to stdout, files, or any text stream

Installation

# Core library (numpy only)
pip install dapple

# Individual CLI tools
pip install dapple[imgcat]          # terminal image viewer
pip install dapple[pdfcat]          # PDF viewer (adds pypdfium2)
pip install dapple[mdcat]           # markdown viewer (adds rich)

# Bundles
pip install dapple[all-tools]       # all CLI tools
pip install dapple[adapters]        # PIL + matplotlib adapters
pip install dapple[dev]             # development (tests + all deps)

Quick Start

import numpy as np
from dapple import Canvas, braille, quadrants, sextants

# Create a canvas from a bitmap
bitmap = np.random.rand(40, 80).astype(np.float32)
canvas = Canvas(bitmap)

# Output to terminal with different renderers
canvas.out(braille)                    # Unicode braille (2x4 dots)
canvas.out(quadrants)                  # Block chars with ANSI color
canvas.out(sextants)                   # Higher-res block chars

# Customize renderer options
canvas.out(braille(threshold=0.3))     # Custom threshold
canvas.out(quadrants(true_color=True)) # 24-bit RGB
canvas.out(braille(color_mode="grayscale"))  # Grayscale ANSI

# Output to file
canvas.out(braille, "output.txt")

# Set default renderer for print()
canvas = Canvas(bitmap, renderer=quadrants)
print(canvas)  # Uses quadrants

Renderers

dapple includes seven renderers, each with different trade-offs:

Renderer	Cell Size	Colors	Best For
braille	2x4	mono/gray/true	Structure, edges, piping, accessibility
quadrants	2x2	ANSI 256/true	Photos, balanced resolution and color
sextants	2x3	ANSI 256/true	Higher vertical resolution
ascii	1x2	none	Universal compatibility, classic look
sixel	1x1	palette	True pixels (xterm, mlterm, foot)
kitty	1x1	true	True pixels (kitty, wezterm)
fingerprint	8x16	none	Artistic glyph matching

Braille (Structure)

from dapple import braille

# Binary threshold
canvas.out(braille)                      # Default threshold 0.5
canvas.out(braille(threshold=0.3))       # Darker threshold
canvas.out(braille(threshold=None))      # Auto-detect from mean

# Color modes
canvas.out(braille(color_mode="none"))       # Plain braille
canvas.out(braille(color_mode="grayscale"))  # 24-level grayscale
canvas.out(braille(color_mode="truecolor"))  # Full 24-bit RGB

Quadrants (Color)

from dapple import quadrants

# Block characters with ANSI colors
canvas.out(quadrants)                    # True color (default)
canvas.out(quadrants(true_color=False))  # 256-color mode
canvas.out(quadrants(grayscale=True))    # Grayscale only

Sixel & Kitty (True Pixels)

from dapple import sixel, kitty

# Sixel for xterm-compatible terminals
canvas.out(sixel)
canvas.out(sixel(max_colors=256, scale=2))

# Kitty graphics protocol
canvas.out(kitty)
canvas.out(kitty(format="png"))          # PNG compression
canvas.out(kitty(format="rgb"))          # Raw RGB

Fingerprint (Artistic)

from dapple import fingerprint

# Glyph matching using font bitmap correlation
canvas.out(fingerprint)
canvas.out(fingerprint(glyph_set="blocks"))    # Block characters
canvas.out(fingerprint(glyph_set="braille"))   # Braille glyphs
canvas.out(fingerprint(cell_width=10, cell_height=20))

Preprocessing

dapple includes preprocessing functions for improved output:

from dapple import (
    auto_contrast,    # Stretch histogram to 0-1 range
    floyd_steinberg,  # Dithering for binary output
    invert,          # Flip brightness values
    gamma_correct,   # Gamma correction
    sharpen,         # Edge enhancement
    threshold,       # Binary threshold
    resize,          # Resize with bilinear interpolation
    crop,            # Extract rectangular region
    flip,            # Mirror horizontally or vertically
    rotate,          # Rotate by degrees
)

# Chain preprocessing
bitmap = auto_contrast(bitmap)
bitmap = floyd_steinberg(bitmap)  # Best for braille
canvas = Canvas(bitmap)
canvas.out(braille)

Floyd-Steinberg dithering is the single most effective improvement for binary output. It creates the illusion of grayscale through varying dot density.

Color Support

Pass RGB colors alongside the bitmap:

import numpy as np
from dapple import Canvas, quadrants

# Grayscale bitmap + RGB colors
bitmap = np.random.rand(40, 80).astype(np.float32)
colors = np.random.rand(40, 80, 3).astype(np.float32)

canvas = Canvas(bitmap, colors=colors)
canvas.out(quadrants)  # Uses RGB colors
canvas.out(braille(color_mode="truecolor"))  # RGB braille

Or use from_array to auto-extract luminance from RGB:

from dapple import from_array

rgb = np.random.rand(40, 80, 3).astype(np.float32)
canvas = from_array(rgb)  # Auto-computes grayscale bitmap

Adapters

Load images from common formats:

# PIL/Pillow
from dapple import from_pil
from PIL import Image

img = Image.open("photo.jpg")
canvas = from_pil(img)                   # original size
canvas = from_pil(img, width=160)        # resize on load
canvas.out(quadrants)

# Matplotlib
from dapple.adapters import MatplotlibAdapter
import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [1, 4, 2])

adapter = MatplotlibAdapter()
canvas = adapter.to_canvas(fig, width=60)
canvas.out(braille)
plt.close(fig)

# Cairo
from dapple.adapters import CairoAdapter
import cairo

surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 200, 100)
ctx = cairo.Context(surface)
# ... draw with cairo ...

adapter = CairoAdapter()
canvas = adapter.to_canvas(surface)
canvas.out(quadrants)

Canvas Operations

# Composition
left = Canvas(bitmap1)
right = Canvas(bitmap2)
combined = left.hstack(right)  # Horizontal stack
combined = left + right        # Same as hstack

top = Canvas(bitmap1)
bottom = Canvas(bitmap2)
combined = top.vstack(bottom)  # Vertical stack

# Overlay
base = Canvas(background)
overlay = Canvas(sprite)
result = base.overlay(overlay, x=10, y=5)

# Crop
cropped = canvas.crop(x1=10, y1=10, x2=50, y2=40)

# Transform
inverted = canvas.with_invert()

CLI Tools

dapple ships several command-line tools, each installed as a standalone entry point:

imgcat photo.jpg                    # view image in terminal
imgcat photo.jpg -r braille         # braille output
imgcat photo.jpg --dither           # Floyd-Steinberg dithering
imgcat photo.jpg -w 120             # custom width

pdfcat document.pdf                 # view PDF pages
pdfcat document.pdf --pages 1-3     # specific pages
pdfcat document.pdf --dpi 300       # higher resolution

mdcat README.md                     # render markdown with formatting
mdcat README.md --no-images         # skip inline images

funcat "sin(x)" -r braille         # plot function
funcat "x**2" --xmin -5 --xmax 5   # custom range

vidcat video.mp4                    # play video in terminal

csvcat data.csv --bar revenue       # chart CSV columns
datacat data.jsonl --spark value    # sparkline from JSONL

Each tool supports -r / --renderer to select the output format (braille, quadrants, sextants, ascii, sixel, kitty, fingerprint) and common preprocessing flags (--dither, --contrast, --invert).

Auto-Detection

dapple can detect terminal capabilities and select the best renderer automatically:

from dapple.auto import auto_renderer, detect_terminal, render_image

# Detect terminal capabilities
info = detect_terminal()
print(info.protocol)       # Protocol.KITTY, Protocol.SIXEL, etc.
print(info.color_support)  # True/False

# Get the best renderer for this terminal
renderer = auto_renderer()             # kitty > sixel > quadrants > braille > ascii
renderer = auto_renderer(plain=True)   # force ASCII (for pipes)

# One-liner: load, detect, render
render_image("photo.jpg")
render_image("photo.jpg", width=640)

When to Use Each Renderer

Scenario	Recommended Renderer
SSH sessions, tmux, screen	braille, quadrants, ascii
Piping output to files	braille, ascii
Screen readers / accessibility	braille
Photo previews	quadrants, sextants
High-quality local display	sixel (xterm), kitty (kitty/wezterm)
Universal compatibility	ascii
Artistic/experimental	fingerprint

License

MIT