ClickyApps

Thumbnail Contrast Checker

Audit and boost thumbnail contrast with smart highlights and instant exports.

Tip: Your data stays in your browser.
Overall
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Upload a thumbnail to start
Needs work

or drag & drop a PNG/JPG/WebP (≤12 MB). Files never leave your browser.

Examples

Load a sample thumbnail with hotspots and presets.

Focus areas

Drag boxes on the preview or adjust them here.

  • Text colour
    Background colour
    Plate colour

Contrast adjustments

Apply overlays and colour tweaks to lift readability.

Overlay colour

Insights

Run an analysis to see tailored suggestions.

AreaOriginalCorrected

Exports & report

FAQs

  • What contrast ratios do you check?
    We compute WCAG 2.1 contrast ratio between your chosen text colour and the average of the pixels inside each focus area. The dashboard shows AA/AAA thresholds for both normal (4.5:1 / 7:1) and large text (3:1 / 4.5:1).
  • Can the checker improve my thumbnail automatically?
    Yes. Use Auto-tune or adjust the overlay, contrast, and highlight plate sliders to darken busy regions. You can also add or remove highlight plates per focus area.
  • What exports are available?
    Download the corrected thumbnail as PNG or JPG, grab a before/after comparison sheet, or export a Markdown report for handoff.
  • Tips for readable thumbnails?
    Keep type bold, aim for ≥4.5:1 contrast, and add a darker highlight plate behind text on busy footage. Sampling multiple hotspots helps catch tricky regions.
  • Does this upload my image?
    No. Everything processes locally in your browser — thumbnails never leave your device.

Guides

YouTube Thumbnail Size and Ratio (2025)
Exact dimensions, aspect ratios, and export settings for YouTube, Shorts, and Instagram thumbnails—with quick presets and quality checks.
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Safe Text Areas for Thumbnails (YouTube/Shorts/Instagram)
Keep your thumbnail text readable across all devices by positioning it inside safe zones—with practical margin guides, platform-specific overlays, and real-device validation using Thumbnail Resizer.
Read →
Convert 16:9 to 9:16 Without Cropping (ffmpeg) (2025)
Transform horizontal video into vertical format using ffmpeg—with pad-vs-crop strategies, copy-ready commands, quality presets, and workflows that preserve subject framing for Shorts, TikTok, and Reels.
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Thumbnail Color Pairings that Pop Without Artifacts (2025)
Build high-contrast color combinations that survive compression and platform overlays using Contrast Checker, plus workflows to keep edges clean on every export.
Read →
Strokes, Shadows, and Outlines: Thumbnail Legibility Toolkit (2025)
Build stroke, shadow, and highlight-plate stacks that keep thumbnail text readable on every feed using Contrast Checker plus fast mobile checks.
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Real-Device Thumbnail Contrast Checks (2025)
Validate thumbnail contrast on real phone and tablet previews so hooks survive upload compression using a Capture > Simulate > Verify workflow.
Read →