Letterproof: Color Contrast
图形与设计
¥8.00 · 专为 iPad 设计。未针对 macOS 验证。
Audit named design roles in light and dark themes, preserve a baseline, create a high-contrast variant, and export exact color tokens alongside an auditable report.
HOW IT WORKS
1. Open Palette, then Theme Proof. Define up to 30 roles with light/dark foreground and background hex values, or load the example themes.
2. Choose normal text, large text or UI component for each role and audit both themes. Filter pairs needing review and inspect their exact ratios.
3. Save a baseline, create a contrast variant, and save it separately. Export the report or color-token JSON and reopen saved proofs after relaunch.
Camera/image audits, manual checks, palette matrices, history and existing tools remain available. Contrast calculations use the current WCAG relative-luminance formula.
WHAT TO KNOW
This checks opaque sRGB color pairs against selected WCAG 2.2 AA thresholds, not complete accessibility compliance. Normal text uses 4.5:1; large text and essential UI boundaries use 3:1. Large text is at least 18 pt regular or 14 pt bold. Choose the correct role and adjacent background. Transparency, gradients, inactive controls, exceptions and actual rendering need separate review. Variants offer black/white foreground alternatives, not nearest-brand colors.
iPhone and iPad.
更多 A clearer App Store name and search details. No other changes in this update.
2.0.1 9月30日
Theme Proof
Audit named design roles in light and dark themes, preserve a baseline, create a high-contrast variant, and export exact color tokens alongside an auditable report.
1. Open Palette, then Theme Proof. Define up to 30 roles with light/dark foreground and background hex values, or load the example themes.
2. Choose normal text, large text or UI component for each role and audit both themes. Filter pairs needing review and inspect their exact ratios.
3. Save a baseline, create a contrast variant, and save it separately. Export the report or color-token JSON and reopen saved proofs after relaunch.
This checks opaque sRGB color pairs against selected WCAG 2.2 AA thresholds, not complete accessibility compliance. Normal text uses 4.5:1; large text and essential UI boundaries use 3:1. Large text is at least 18 pt regular or 14 pt bold. Choose the correct role and adjacent background. Transparency, gradients, inactive controls, exceptions and actual rendering need separate review. Variants offer black/white foreground alternatives, not nearest-brand colors.
2.0 9月15日
This update sharpens the interface: the iPad layout now uses a centered, comfortable reading width instead of stretching edge to edge, plus small display fixes. iPhone is unchanged.
1.4.1 6月26日
What's New in Letterproof 1.4
Palette Contrast Matrix - the new Palette tab lets you enter your entire design-system colour palette (up to 12 colours) and see an NN compliance grid in one view. Every text/background combination is scored simultaneously: each cell shows the WCAG grade (AAA/AA/FAIL) and the contrast ratio right on the coloured background, so failing pairs are visible at a glance. Toggle to large-text thresholds with one tap. Tap any cell for a full detail sheet: contrast bar, APCA Lc score, colour-fix suggestions, and colour-blindness simulations. Share the full matrix as a plain-text report. The palette is saved between sessions.
Bold-text threshold - WCAG 1.4.3 defines large text as 18 pt regular *or* 14 pt bold, but Letterproof previously applied only the 18 pt boundary (the conservative fallback when weight isn't detectable from pixels). A new `isLargeTextSize(_:isBold:)` API now supports both boundaries. The Manual tab's large-text toggle label clarifies the 18 pt regular / 14 pt bold distinction, and the ReadingDetailSheet explanation text references the bold rule.
1.4 6月23日
Export a shareable Accessibility Report — a polished PDF (and annotated PNG) of any audit, ready to drop into a compliance ticket, parent-teacher packet, or client deliverable. Plus contrast-accuracy and overlay-alignment fixes for portrait camera photos and wide-gamut images.
1.3 6月18日
What's New in Letterproof 1.2
Colour-fix suggestions — when any text region fails WCAG AA, Letterproof now shows up to four alternative colours that would pass: darken text, lighten text, darken background, or lighten background. Each suggestion keeps the original hue and saturation, changes only lightness, and shows the contrast it achieves. Tap any hex code to copy it to the clipboard. Available in both the reading detail sheet and the Manual tab.
APCA Lc score — every contrast check now includes the APCA (Advanced Perceptual Contrast Algorithm) perceptual-contrast score alongside the WCAG 2.2 ratio. APCA is the contrast method being evaluated for WCAG 3; it is polarity-aware and better reflects how human vision perceives lightness differences. A readability note (body text / UI text / headlines / too low) appears next to the Lc value. Clearly labelled as experimental — WCAG 2.2 remains the enforceable standard.
CSV export — the share menu in any audit result now offers "Export CSV" in addition to the existing plain-text report. The CSV file has 11 columns — WCAG grade, contrast ratio, APCA Lc, OCR text, estimated point size, foreground hex, background hex, and audit timestamp — sorted worst-first. Open in Numbers or Excel, or paste into an accessibility report template.
1.2 6月15日
What's New in Letterproof 1.1
Manual colour checker — a new tab lets you type any two hex colour codes and get an instant WCAG contrast ratio and AA / AAA verdict. Flip a toggle for large-text thresholds. No camera needed — useful any time you are reviewing a Figma file, design brief, or brand guide.
Colour-blindness simulations — every reading detail sheet now shows how the text / background pair appears under Deuteranomaly, Protanomaly, and Tritanomaly. The simulation uses the Machado et al. (2009) physiologically-based model. The Manual tab includes the same simulations for any colour pair you type in. A red-on-green pair that passes WCAG on paper might still fail readers with colour-vision deficiency — this makes that visible.
Share / export — tap the share button from any audit result to get a plain-text report with the overall verdict, region count, and every reading's grade and contrast ratio. Also available in the Manual tab.
1.1 6月14日
A clearer App Store name and search details. No other changes in this update.
更多 版本 2.0.1 9月30日
未收集数据 开发者不会从此 App 中收集任何数据。