Edge detection: Sobel & Canny

Sobel measures how fast brightness changes at every pixel — mathematically, the gradient. Where the gradient is large, there's an edge. Our Pencil Sketch and Ink Outline tools build their lines from Sobel edges, then shape them with thresholds and softness.

Canny is the more refined cousin: it suppresses noise first, then keeps only the strongest edges as thin lines. Our Ink Outline approximates this behavior with smoothing plus a threshold.

Geometry: Delaunay & low poly

Delaunay triangulation connects a set of points into triangles such that no point lies inside another triangle's circumcircle. The payoff: the most balanced mesh possible — no slivers, no overlaps. We use it to rebuild photos as faceted low-poly art, sampling more points where edges are strong.

Low poly is the art style: hundreds of flat triangles, each filled with the average color of the photo beneath it.

Color: quantization & median cut

Quantization reduces the number of distinct colors. Posterize divides each channel into a fixed number of steps; Cartoon does the same and adds edges. The result is flat, graphic, 'printed' color.

Median cut is how our Color Palette tool finds dominant colors: it repeatedly splits the color space at the median until the target number of swatches is reached, then averages each bucket. Simple, fast, and reliably pleasing palettes.

Texture: blur, grain & halftone

Box blur averages each pixel with its neighbors — cheap and effective. Watercolor stacks several shifted box blurs to simulate pigment bleeding; Tilt-Shift applies a blur that fades with distance from a focus line.

Film grain adds random luminance noise; halftone converts brightness into dot size, exactly like newspaper printing; chromatic aberration (used in Glitch and VHS) offsets color channels to mimic lens and signal artifacts.

The takeaway

None of this requires a math degree to enjoy. The tools hide the algorithms and expose what matters: a slider for how strong, a slider for how soft, a button for random. Understanding the terms just makes you a better artist with them — you'll know why a low-poly face still looks like a face, and why raising the threshold cleans up an ink sketch.

And since everything runs locally, you can experiment with every parameter without cost or consequence — the fastest way to learn any of these concepts is to drag the sliders.

Histogram & tone mapping

A histogram is a bar chart of your photo's brightness distribution — how many pixels are dark, mid, and bright. Effects like Posterize and Duotone work by remapping these tones. Tone mapping is the general term for any remapping: push shadows darker, pull highlights brighter, or flatten everything. Understanding your histogram explains why a flat photo yields flat effects — garbage tonal range in, garbage tonal range out.

Sampling & resampling

Every effect that changes size — pixel art, low poly, mosaic — involves sampling: choosing which pixels survive when you shrink. Simple nearest-neighbor sampling keeps hard edges (perfect for pixel art); bilinear and bicubic interpolation smooth the result (better for watercolor and oil). When an effect looks unexpectedly sharp or soft, the resampling method is usually the quiet culprit.

Why it matters to you

You don't need to implement these algorithms — that's the tool's job. But knowing their names and behaviors turns slider-pushing into informed slider-pushing. When a client asks 'can you make it smoother?', you know whether to reach for softness, blur, or resampling. Vocabulary is leverage; the glossary is your vocabulary.

Frequently asked questions

Do I need to understand these terms to use the tools? No. Every effect works with plain-language sliders. The glossary exists so that when you want to go deeper — asking a client, searching for a tutorial, or explaining to a friend — you have the vocabulary.

What's the difference between a filter and an algorithm? An algorithm is the math that transforms pixels; a filter is the packaged result. Sobel is an algorithm; 'Pencil Sketch' is the filter that packages it with thresholds and softness into something usable.

Are these algorithms standard? Yes — Sobel, Delaunay, median cut and box blur are textbook techniques used across the industry. The tool's job is to combine them with sensible defaults and instant feedback.

Where can I learn more? The algorithms are taught in any computer-graphics course and documented widely online. But the fastest teacher remains this site: drag the sliders, watch what changes, and the terms start to mean something real.