Building a Style Library¶

You just spent ninety minutes on a seven-layer composition with tuned crosshatch angles, balanced thresholds, and a Trace outline layer with exactly the right smoothing value. It looks right. Now you need to apply the same look to thirty more images for a client's annual report.

You could rebuild those seven layers from memory for each image. Or you could save the style once and transfer it to every image in seconds.

A style in Vexy Lines is the complete set of fill layers, parameters, masks, and groups in a .lines document: everything except the source image. Swap the source image and Vexy Lines reinterprets the new photograph through the same fill recipe. This is style transfer, and it's how you turn a one-off experiment into a repeatable tool.

What a Style Contains¶

When you save a .lines file, it stores:

Element	Stored	Transferred
Fill layers (type, parameters)	Yes	Yes
Layer order	Yes	Yes
Masks	Yes	Yes (but may need adjustment for different compositions)
Groups and nesting	Yes	Yes
Mesh warping	Yes	Yes
Clone relationships	Yes	Yes
Source image	Yes	Replaced during transfer
Canvas size	Yes	Adjusted to match new source

The source image is the only element that changes during style transfer. Everything else, the fill recipe, stays intact.

Saving a Style Template¶

Build your composition on any source image. Get every parameter exactly right.
File > Save As with a descriptive name: portrait-engraving-crosshatch.lines, landscape-atmospheric-depth.lines, pop-art-halftone-bold.lines.
Store the file in a dedicated folder: ~/Vexy Styles/ or whatever naming convention you prefer.

That's it. The .lines file is the style template. There is no separate "style format": the document itself carries all the information.

Naming Conventions¶

As your library grows, naming matters. A recommended pattern:

Text Only

[subject]-[technique]-[variant].lines

Examples:

portrait-crosshatch-classic.lines
portrait-crosshatch-fine.lines
portrait-halftone-pop.lines
landscape-wave-atmospheric.lines
landscape-fractal-dense.lines
product-linear-technical.lines
texture-scribble-organic.lines

Folder Organisation¶

Text Only

~/Vexy Styles/
├── Portraits/
│   ├── portrait-crosshatch-classic.lines
│   ├── portrait-crosshatch-fine.lines
│   ├── portrait-halftone-pop.lines
│   └── portrait-trace-minimal.lines
├── Landscapes/
│   ├── landscape-wave-atmospheric.lines
│   └── landscape-fractal-dense.lines
├── Products/
│   ├── product-linear-technical.lines
│   └── product-halftone-catalog.lines
├── Textures/
│   ├── texture-scribble-organic.lines
│   └── texture-fractal-mathematical.lines
└── Screen Print/
    ├── screenprint-2color-bold.lines
    └── screenprint-3color-cmyk.lines

Style Transfer: The Manual Method¶

The simplest way to apply a saved style to a new image:

Open the style template (.lines file).
Replace the source image. Drag your new photo onto the canvas (or use File > Replace Source Image). The fills immediately recalculate against the new photo's brightness data.
Adjust masks. The masks from the template were shaped for the original photo. If the new photo has a different composition (subject in a different position, different framing), you'll need to repaint or adjust the masks.
Fine-tune thresholds. Different photos have different tonal distributions. A template built on a high-contrast portrait may need threshold adjustments on a low-contrast portrait.
Save As with a new name (to preserve the template).

This takes 2–10 minutes per image depending on how much mask and threshold adjustment is needed.

Style Transfer: The SDK/CLI Method¶

For batch processing (applying the same style to dozens or hundreds of images), use the command-line tools. A .lines file is the style source; you do not need to export a separate JSON style file.

Apply a Style¶

vexy-lines-cli style-transfer --style portrait-engraving.lines --images new-photo.jpg --output-dir ./results --format svg

The CLI opens a new document for the source image, applies the fill tree from the style .lines file, renders, and writes the requested output format.

Batch Apply¶

vexy-lines-cli style-transfer --style portrait-engraving.lines --input-dir ./photos --output-dir ./results --format svg

Every image in ./photos gets the style applied. The output directory fills with rendered files.

Export Existing .lines Files¶

vexy-lines-cli export ./results --format svg --output ./svgs

All .lines files in the results directory export to SVG. The export command accepts either one .lines file or a directory and uses --output for the destination file or directory.

Style Interpolation¶

What happens when you blend two styles together? Style interpolation takes two style templates and generates a hybrid, with a blend factor controlling how much of each style appears in the result.

How It Works¶

vexy-lines-cli style-transfer --style style-a.lines --end-style style-b.lines --input-dir ./frames --output-dir ./hybrid

The first image gets Style A, the last image gets Style B, and images between them receive interpolated fill parameters. For direct control over one blend ratio, use interpolate_style(a, b, t) from vexy_lines_api.

The interpolation blends numeric parameters: intervals, angles, thresholds, thickness values, randomization, smoothing. Non-numeric properties (fill type, masks, colours) are taken from Style A when blend < 0.5 and Style B when blend ≥ 0.5.

Practical Uses¶

Gradual transitions in a series. For a set of 10 images (a gallery wall, an animation sequence, a book chapter), interpolate from Style A (sparse, light) to Style B (dense, dark) across the series. Each image gets a slightly different blend value, creating a visual progression.
Finding the sweet spot. You built a bold engraving style and a delicate fine-line style. Neither is quite right. Interpolate at 0.3 (mostly bold with some delicacy) or 0.7 (mostly delicate with some weight) to find a hybrid that combines the best qualities.
Animation. For video style transfer, interpolate across frames to create evolving visual textures. The style shifts gradually over time. See the video documentation for details.

Your First Five Styles¶

If you're starting a style library from scratch, build these five first. They cover the most common use cases and give you a foundation to build variants from.

1. Classic Engraving¶

Based on the Portrait Engraving recipe. Linear at 15° + Linear at 75° for crosshatch + Trace outlines. Universal starting point for portraits and figurative work.

2. Atmospheric Landscape¶

Based on Landscape and Nature. Wave for sky + Linear for midground + Fractal for foreground + Trace outlines. The interval gradient (wide-to-tight, top-to-bottom) creates depth in any landscape.

3. Pop Art Halftone¶

Based on the Composition Recipes pop-art recipe. Halftone with Dynamic Color + bold Trace outlines. Works on any bold, simple composition.

4. Technical Line Drawing¶

Linear at 0° and 90° with zero randomization + Trace outlines at max smoothing. Clean, precise, mechanical. Works for product photography, architecture, and engineering subjects.

5. Organic Texture¶

Scribble background + Handmade detail + Fractal midlayer. The all-organic style: no straight lines, no grid patterns, no mechanical precision. Works for natural subjects, abstracts, and textures.

A .lines file is a complete, self-contained style. To share:

Email or file share the .lines file. The recipient opens it in Vexy Lines and replaces the source image with their own.
Publish to a shared folder (Dropbox, Google Drive, network share). Team members pull templates as needed.
Include in a project repository. If your team uses version control, styles can be committed alongside other project assets.

The only dependency is Vexy Lines itself. No plugins, no fonts, no external resources: everything is in the .lines file.

Maintaining a Library¶

As your library grows past twenty or thirty styles, maintenance matters:

Delete styles you never use. If you haven't touched texture-fractal-experiment-7.lines in six months, it's clutter.
Version your favourites. When you improve a style, save it as a new version (portrait-crosshatch-v2.lines) rather than overwriting the original. You may want to go back.
Add notes. Keep a text file (style-notes.md) alongside your library with one-line descriptions: "Classic engraving for high-contrast portraits, 6 layers, works best with faces lit from upper-left."
Test on diverse images. A style built on one portrait may not work on all portraits. Test each template on at least 3–5 different source images before considering it "library-ready."

Summary¶

Action	How
Save style	File > Save As (the .lines file is the style)
Apply style manually	Open template, replace source image, adjust masks, Save As
Apply style via CLI	`vexy-lines-cli style-transfer --style template.lines --images photo.jpg --output-dir ./results`
Batch apply	`vexy-lines-cli style-transfer --style template.lines --input-dir ./photos --output-dir ./results`
Interpolate styles	`vexy-lines-cli style-transfer --style a.lines --end-style b.lines --input-dir ./frames --output-dir ./results`
Export .lines files	`vexy-lines-cli export ./results --format svg --output ./svgs`

Next: Preparing Files for Print