Themes

The ImageRenderer accepts a Theme that bundles background colour, glyph palette, noise density and optional font.

Built-in presets

from captchakit import ImageRenderer, Theme

ImageRenderer(theme=Theme.CLASSIC)       # default
ImageRenderer(theme=Theme.DARK)          # dark canvas, pastel glyphs
ImageRenderer(theme=Theme.PASTEL)        # warm, low-contrast
ImageRenderer(theme=Theme.HIGH_CONTRAST) # WCAG AA: black on white, no noise

• HIGH_CONTRAST is the accessibility-friendly default for users with low vision. It removes decorative noise lines entirely.
• DARK is suited for dark-mode UIs; it uses a near-black background and light-on-dark glyphs.

Custom theme

Theme is a frozen dataclass:

from captchakit import ImageRenderer, Theme

brand = Theme(
    bg_color=(250, 240, 220),
    palette=(
        (110, 70, 20),
        (170, 100, 30),
        (200, 130, 40),
    ),
    noise_lines=3,
    font_path="/fonts/MyBrand-Bold.ttf",
)

renderer = ImageRenderer(width=260, height=90, theme=brand)

Field	Default	Notes
bg_color	(245, 245, 245) light gray	RGB tuple
palette	5 muted colours	At least one entry required
noise_lines	4	0 disables decorative noise
font_path	None (Pillow default)	TrueType file path

The renderer's own font_path argument still wins over the theme's — use it to override the theme bundle without redefining the colours.