48 lines
2.1 KiB
Markdown
48 lines
2.1 KiB
Markdown
# Generated CAPTCHA image styles
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The self-hosted and managed engines support 18 concrete renderers plus `random`.
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## Concrete styles
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| Style | Main effect | Suggested use |
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| --- | --- | --- |
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| `classic` | Dots, crossing lines, glyph jitter | General default pool |
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| `collision` | Overlapping coloured glyphs and bars | Medium or hard challenges |
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| `snow` | Dense snow-like speckles | Medium challenges |
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| `corrosion` | Eroded glyph patches and rust-like noise | Medium or hard challenges |
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| `spiderweb` | Connected web lines and nodes | Medium challenges |
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| `cross-shadow` | Multi-colour offset shadows | Medium challenges |
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| `split` | Horizontally shifted image bands | Medium or hard challenges |
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| `split2` | Vertically shifted image strips | Medium or hard challenges |
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| `cut` | Slashed and interrupted character strokes | Medium challenges |
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| `darts` | Radial lines and target rings | Medium challenges |
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| `distortion` | Two-axis sinusoidal distortion | Medium or hard challenges |
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| `stitch` | Dashed seams and cross stitches | Easy or medium challenges |
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| `striped` | Diagonal and horizontal stripes | Easy or medium challenges |
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| `wave` | Strong wave transformation | Medium or hard challenges |
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| `grid-noise` | Grid lines and translucent cells | Easy or medium challenges |
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| `scribble` | Random-walk line scribbles | Medium challenges |
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| `pixel` | Pixel blocks and shifted regions | Medium challenges |
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| `broken-lines` | Missing stroke segments and fragments | Medium or hard challenges |
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## Random pool
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```wrn
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<Captcha
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type="alphanumeric"
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action="signup"
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imageStyle="random"
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allowedStyles="classic,snow,spiderweb,distortion,wave"
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excludedStyles="collision"
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disturbance="50"
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/>
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```
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The engine resolves one concrete style per challenge. Refreshing creates a new challenge and selects again. Challenge metadata contains `imageStyle`, `requestedImageStyle`, and `imageStylePool`; it never contains the answer.
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## Accessibility
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Keep `showAudio="true"` or provide another non-visual path. High disturbance and hard renderers should not be the only completion option.
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