Checking transparent comic pages in ManYue: background compositing versus missing lines

English translation of the Chinese original, translated on 2026-11-03. Original publication dates, attribution, code and version notes are retained.

Black lines in a transparent PNG may be hard to see on a dark background, just as white lines may disappear against a light one. Use a self-made sample to distinguish compositing, missing source content and display-path differences. This concerns transparent page images, not recolouring ordinary white-paper scans or guaranteeing automatic paper backgrounds.

Create transparent and opaque references

Draw black and white lines, a semi-transparent grey patch and coloured corner marks in a familiar tool. Save a transparent PNG and an otherwise identical opaque white-background copy, keeping dimensions equal and names distinct. Preserve the editable original. Verify actual transparency in a checkerboard-capable tool rather than inferring it from PNG alone. Self-made content avoids using a private book and keeps the comparison focused on background and delivery, not different artwork.

Verify the original marks

Inspect the transparent sample over light and dark backing colours, checking every mark and soft edge. A checkerboard preview is not necessarily part of the saved image; a baked-in checkerboard is different opaque content. These controls belong to the external tool, not a promised ManYue transparency panel. Later compare only the backgrounds and viewing controls actually available in the reader.

Import both references as separate pages

Import the two references through an established local-image or simple-archive flow, preserving clear markers and order. Check corners and complete dimensions before line visibility. Keep processing and resizing unchanged. Use a verified packaging path rather than generalising to every animated PNG or bit depth. Open actual pages because cover thumbnails can follow a different rendering path and do not establish body-page transparency behaviour.

Compare available light and dark display states

Compare the pages under light/dark conditions the reader actually exposes. Separate menu appearance from backing behind the image: a dark menu does not prove a dark image backing. A changing transparent page with a stable opaque reference points toward compositing, while shared anomalies require further checks. Change one control at a time without resaving sources. If no background control exists, record the observed state rather than inventing a button or changing unrelated system protections.

Identify what appears to disappear

Background-dependent black or white visibility differs from a region blank in every condition. Recheck source pixels and the opaque control. Semi-transparent grey should depend on the backing and is not automatically corrupt. Missing corner marks call for crop, scale or content checks. Report location and conditions rather than only “transparency unsupported.” PNG compositing explains the concept, but a format specification does not certify this app’s handling of a particular file.

Create a separate fixed-background reading copy if needed

If the intended use requires white paper and the current path is inconvenient, composite an explicit background externally where authorised and save a separate reading copy. Validate lines, soft edges and corners on the sample first. Preserve the transparent original: compositing changes transparency and does not prove recovery of original paper colour or universal losslessness. Label the derivative and re-establish position by chapter/scene if it gains a separate identity rather than assuming automatic progress inheritance.

Keep local and remote comparisons equivalent

For a remote comparison use the same self-made sample and determine whether the service returns a thumbnail or composited derivative. Matching names do not prove identical bytes or alpha; state uncertainty when necessary. Compare backing, corners and edges before isolating a remote-only issue. Downloaded success does not certify every online image request. Use the sample and conditions in reports without private connection details or repeatedly deleting working originals.

Acceptance and rollback

Finish with evidenced differences between transparent and fixed-background pages, verified source marks and reproducible display conditions. Menu and image backing can differ. Renaming an extension neither converts the file nor adds transparency support. Retain baseline settings and both samples. Choose a complete readable route or explicit-background derivative without requiring every transparent design to contrast equally on every background or claiming universal PNG-variant compatibility.

ManYue appearance: dark mode, backgrounds and screen display; ManYue test comic: verify an import with six numbered pages.

Checked on November 3, 2026: Apple public version information lists ManYue 2.0.4, requiring iOS / iPadOS 15.0 or later. Feature scope follows the official App Store description and the installed version. This article describes actions and content checks you can perform; it does not claim step-by-step physical-device or private-server testing. Manual records, external tools and application controls are identified separately, and code observations or personal inferences are not presented as verified automatic capabilities.

For transparency and background compositing, see the W3C PNG specification. A format definition does not replace testing a particular file in an application.