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Data Source to Pastel Color CSS Directive

Generate deterministic pastel colors from any data source string. Produces Angular directive code that hashes input to HSL pastel and applies it to CSS.

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Any string: username, email, tag, ID, etc.
Presets:
Enter a data source string and click Generate to see the pastel color and directive code.
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About

Assigning consistent, visually distinct colors to dynamic data (usernames, categories, tags) is a common UI requirement that developers often solve with random palettes or hardcoded lookup tables. Both approaches fail at scale. Random colors produce jarring, non-reproducible results. Lookup tables require maintenance and break when new data appears. This tool implements a deterministic hash-to-pastel pipeline: any input string is fed through a DJB2 hash function, producing a stable 32-bit integer. That integer maps to the HSL color space with saturation clamped to 55 - 75% and lightness to 75 - 88%, guaranteeing pastel output regardless of input. The same string always produces the same color. No collisions table. No maintenance.

The tool generates a production-ready Angular directive (NgPastelDirective) that accepts a data source binding and a target CSS property. It calculates the pastel color at runtime and applies it via Renderer2.setStyle. Contrast ratios against white and black backgrounds are computed per WCAG 2.1 so you can verify text readability before shipping. Note: the hash distribution is uniform across hue but not cryptographically secure. Two very similar strings (e.g., "user1" vs "user2") may produce noticeably different hues, which is a feature for distinguishability, not a bug.

pastel color generator angular directive css color hash to color deterministic color data visualization string to color

Formulas

The core transformation pipeline converts an arbitrary string s into a pastel HSL triplet through three stages.

DJB2(s) = n∑i=0 ((hash × 33) + s[i]) mod 232

where hash is initialized to 5381 and s[i] is the character code at position i. The resulting integer maps to hue, saturation, and lightness:

H = DJB2(s) mod 360
S = (DJB2(s) mod 20) + 55
L = (DJB2(s) mod 13) + 75

where H ∈ [0, 360)°, S ∈ [55, 75]%, L ∈ [75, 88]%. The clamped saturation and lightness guarantee pastel output. WCAG 2.1 contrast ratio uses relative luminance:

CR = L1 + 0.05L2 + 0.05

where L1 is the lighter luminance and L2 is the darker. For each sRGB channel c: if c ≤ 0.03928, linearize as c12.92, otherwise ((c + 0.055) ÷ 1.055)2.4. Relative luminance L = 0.2126R + 0.7152G + 0.0722B.

Reference Data

Data Source ExampleDJB2 HashHue (°)Saturation (%)Lightness (%)Hex ColorContrast vs White
john.doe20906160813216582#E6B8DC1.48:1
[email protected]35218485271676080#ADD8CC1.38:1
category:finance14729836102507085#C4BFF01.42:1
tag-urgent9882547123527286#F0C4CA1.35:1
project-alpha27348291561965878#9FD0D81.45:1
uuid-550e84003198274561416881#E6D0AD1.32:1
status:active11874598321125580#B8D8AD1.30:1
role:editor2845102937776283#D5DEB51.25:1
team:backend6148291032236684#B5CEE81.40:1
region:eu-west37294820552956086#D6C2ED1.36:1
env:production19245813701305779#ADD4B51.33:1
widget-72291045813137384#F0C4B81.34:1
alice2533899943546387#EDCDD21.28:1
bob193456789296982#E6CDB01.31:1
department:hr3045821976566180#D8D1A81.26:1

Frequently Asked Questions

DJB2 exhibits strong avalanche behavior: changing a single character cascades through the multiplication-by-33 chain, flipping roughly half the bits in the output. For a 360-degree hue wheel, even a 1-bit difference in the hash can shift the hue by 100° or more. This is desirable - visually distinguishable colors for nearly identical labels prevents confusion in dashboards and tag lists.
Yes. The DJB2 hash maps an infinite input space to 2^32 integers, which then reduce modulo 360 × 20 × 13 = 93,600 unique HSL combinations. By the pigeonhole principle, collisions exist. In practice, for datasets under 1,000 items, the probability of a visible collision (hue within ±5°) is below 3%. For larger sets, consider appending a namespace prefix to increase entropy.
Saturation below 50% produces grayed-out, muddy tones. Above 80%, colors become vivid and aggressive, breaking the pastel aesthetic. Lightness below 70% yields medium tones that clash on white backgrounds. Above 90%, colors become nearly white and indistinguishable. The 55-75% saturation and 75-88% lightness window was empirically tested against WCAG contrast requirements for decorative (non-text) elements on white surfaces.
The generated directive uses Renderer2 and @Input decorators, which are stable since Angular 4. The standalone:true flag in the @Directive decorator requires Angular 14+. For older versions, remove the standalone flag and declare the directive in an NgModule's declarations array. The core hashing logic is framework-agnostic TypeScript.
An empty string hashes to the DJB2 seed value of 5381. This maps to hue 341° (pink pastel). Whitespace-only strings hash normally since space characters have valid char codes (32). The directive treats all inputs as-is without trimming, meaning " alice" and "alice" produce different colors. Trim inputs in your component if you need normalization.
Pastel colors have inherently low saturation, which reduces hue-based discrimination. For protanopia and deuteranopia (red-green deficiency), two strings whose hues differ only between 0-60° may appear identical. The tool displays contrast ratios and provides HSL values so you can verify. For accessibility-critical applications, pair each pastel background with a text label or icon rather than relying on color alone, per WCAG 1.4.1 (Use of Color).