About

Distributing color across text requires mapping each character (or word) to a position on the HSL color wheel. A naive approach assigns random colors, producing visual noise. This tool computes evenly-spaced hue values across a configurable arc of the 360° spectrum, maintaining constant S (saturation) and L (lightness) for perceptual uniformity. The output is real, copy-pasteable code: inline HTML <span> elements, ANSI 256-color escape sequences for terminal use, or raw CSS class mappings. Misconfigured ANSI codes break terminal rendering and corrupt log files. Incorrect HTML color spans produce invalid markup that fails accessibility contrast checks.

The ANSI output maps each computed RGB triplet to the nearest color in the xterm-256 palette using Euclidean distance in RGB space. This approximation loses fidelity below 16 distinct hues. For terminal output, the tool assumes xterm-compatible \x1b[38;5;nm sequences. Results vary on Windows cmd.exe without ANSI support enabled. The HTML output produces valid, accessible markup with each character wrapped in a <span> carrying an inline style attribute.

Formulas

Each colorizable unit (character, word, or line) at index i out of n total units receives a hue value computed by linear interpolation across the configured arc:

H_i = H_start + in − 1 × (H_end − H_start)

where H_start and H_end define the hue arc in degrees (0 - 360), i is the zero-based index, and n is the total count of colorizable units. For a full rainbow, H_start = 0 and H_end = 360.

The final color is expressed as:

hsl(H_i, S, L)

where S = saturation (0 - 100%) and L = lightness (0 - 100%).

For ANSI 256-color mapping, the nearest palette index is found via Euclidean distance in RGB space:

d = √(r₁ − r₂)² + (g₁ − g₂)² + (b₁ − b₂)²

where (r₁, g₁, b₁) is the target color and (r₂, g₂, b₂) iterates over the 256 xterm palette entries.

Reference Data

Color Mode	Hue Range	Best For	Output Format	Color Count
Classic Rainbow	0° - 360°	Full spectrum text	HTML / ANSI / CSS	Unlimited
Warm Gradient	0° - 60°	Red to yellow themes	HTML / CSS	Unlimited
Cool Gradient	180° - 270°	Cyan to purple themes	HTML / CSS	Unlimited
Pastel Rainbow	0° - 360°	Soft, readable text	HTML / CSS	Unlimited
Neon	0° - 360°	High-contrast displays	HTML / ANSI	Unlimited
ANSI 16-Color	Fixed palette	Legacy terminals	ANSI escape codes	16
ANSI 256-Color	Mapped from RGB	Modern terminals	ANSI escape codes	256
Monochrome Gradient	Single hue	Lightness variation only	HTML / CSS	Unlimited
Custom Range	User-defined	Brand-specific palettes	All formats	Unlimited
Per-Word	Any	Readable colored output	All formats	Word count
Per-Line	Any	Log file highlighting	All formats	Line count
Per-Character	Any	Maximum color density	All formats	Char count

Frequently Asked Questions

The xterm-256 palette contains only 216 color cube entries (6×6×6 grid in RGB space) plus 24 grayscale shades and 16 system colors. When mapping an arbitrary HSL-derived RGB value, the tool finds the nearest palette entry by Euclidean distance. At high character counts with subtle hue shifts (below approximately 1.5° per step), multiple consecutive characters may map to the same ANSI index, creating visible banding. HTML output preserves full 24-bit color and does not suffer this limitation.

Spaces, tabs, and newlines carry no visible glyph. Assigning color spans to them inflates output size without visual effect and produces invalid ANSI sequences in some terminal emulators. The tool skips whitespace during index assignment but preserves it in the output. This means n (total colorizable units) counts only visible characters, words, or lines depending on selected granularity.

The tool wraps the hue arc correctly. If H_start is 300° and H_end is 60°, the interpolation crosses the 360°/0° boundary, producing a magenta-to-red-to-yellow sequence. The effective arc length is computed modulo 360°. This allows reverse rainbows and partial spectrum selections that cross the red boundary.

The tool splits on whitespace boundaries only. A hyphenated compound like "well-known" counts as one unit and receives one color. Punctuation attached to a word (e.g., 'hello,') stays with that word. For finer control, use per-character mode where each glyph including punctuation gets its own hue step.

Copy the ANSI output and paste it into an echo -e command or printf statement in bash. The escape sequences use the format \x1b[38;5;Nm where N is the palette index. Remember to append \x1b[0m at the end to reset the terminal color. The tool includes this reset automatically. Note: piping ANSI-colored output through programs that strip escape codes (like grep without --color) will display raw escape characters.

Saturation between 70% and 85% with lightness between 40% and 50% maintains sufficient contrast against white (#FFFFFF) for WCAG AA compliance at normal text sizes. The default Pastel preset uses S=80%, L=65%, which sacrifices some contrast for aesthetic softness. For accessibility-critical applications, use the Neon preset (S=100%, L=45%) which exceeds 4.5:1 contrast ratio for all hues except yellow, where lightness drops automatically to 38%.