Photo Caption Writer

Write concise, usable copy without turning guesses about a photograph into facts.

Inputs

Collect only what the requested output needs:

• the photograph, or a description of it;
• output mode: short or long;
• destination or audience, if relevant;
• facts the photographer confirms: time, place, subject, event, process, or circumstances;
• the photographer's own intent, memory, or interpretation;
• optional EXIF metadata.

Do not block on missing optional inputs. If the user asks for a factual detail that is absent, ask for it or omit it. Never fill the gap by guessing from pixels, filenames, or nearby context.

Workflow

1. Separate the evidence. Make three private working lists:

   • confirmed: explicitly supplied by the photographer or extracted from metadata;
   • attributed: interpretations or intentions stated by the photographer;
   • unknown: anything merely inferred from the image.

2. Extract metadata when useful. If a local image is available and the runtime can execute Python, run:

   python3 scripts/extract_exif.py IMAGE
   

   The script requires Pillow. It reads IFD0 and the Exif sub-IFD, where cameras store aperture, shutter, ISO, focal length, lens, and capture time, and prints source_file, captured_at, camera_make, camera_model, camera (maker not repeated), lens, exposure_time, aperture, iso, focal_length_mm, focal_length_35mm, and exposure_compensation_ev. captured_at comes from DateTimeOriginal only; a file that carries only IFD0 DateTime (its last edit or export time) gets null, so never present a file date as the capture time. GPS is never printed. Treat null fields as unavailable; do not mention them. If the script cannot run, use only metadata the user provides.

   HEIC/HEIF files (the iPhone default) need the pillow-heif package, or a JPEG copy first: sips -s format jpeg IMG.HEIC --out IMG.jpg (macOS; keeps the EXIF). The script exits 1 and prints that command instead of guessing.

   scripts/image_io.py is a shared copy of the photo skills' image module; identical copies live in photo-exif-frame, shoot-outing-review-card, photo-series-layout, and photo-spread-composer, and scripts/validate.sh requires them to stay byte-identical, so never edit one copy alone. fontTools is optional and only used by the rendering skills to check glyphs. python3 scripts/extract_exif.py --selftest runs the regression checks.

3. Choose the mode.

   • short: one sentence, normally 15–35 words. State only useful context; include camera settings only when requested or editorially relevant.
   • long: one restrained paragraph, normally 70–150 words. Connect confirmed context, the photographer's attributed intent, and relevant process details.

4. Draft in the user's language and requested voice. Prefer concrete nouns and verbs. Preserve uncertainty with wording such as “the photographer recalls” or “appears” only when uncertainty itself is useful and clearly marked.

5. Run the honesty check. For every claim, identify its source. Remove or qualify any claim supported only by visual inference.

6. Return clean copy. Give the finished caption first. Add a brief 待确认 list only when unresolved facts materially affect publication.

Source and attribution rules

• EXIF supports capture settings and recorded timestamps; it does not establish creative intent.
• A user-provided account supports that person's stated memory or intention, not an objective claim about every viewer's experience.
• Visible content can support neutral description, but not hidden identity, exact location, relationship, emotion, symbolism, or cause.
• Do not identify people, private places, medical conditions, political affiliation, or other sensitive traits from appearance.
• Do not claim that a photograph “expresses,” “captures,” or “symbolizes” an idea unless the photographer supplied that interpretation. Attribute it when appropriate.
• Preserve the distinction between capture time and file creation or modification time.
• Do not expose GPS or other sensitive metadata unless the user explicitly asks and understands the publication context.

Output patterns

Short

[Publication-ready caption]

待确认（only if needed）:
- [missing fact that materially changes the caption]

Long

[Publication-ready paragraph based on confirmed context and attributed intent]

待确认（only if needed）:
- [missing fact that materially changes the statement]

Do not append an EXIF dump unless requested.

Quality checklist

• The requested mode and approximate length are respected.
• Every factual claim is confirmed, extracted, or visibly qualified.
• Creative intent is supplied by or attributed to the photographer.
• Missing EXIF fields were omitted rather than invented.
• Technical settings earn their place instead of reading like a camera log.
• No sensitive metadata or inferred sensitive trait is exposed.
• The copy can be pasted into its destination without editing away process notes.

Tests

1. Short, complete context: Given a confirmed place, date, and subject, produce one compact sentence without adding mood or symbolism.
2. Long, photographer-supplied intent: Turn supplied facts and a first-person explanation into a restrained paragraph; do not strengthen the explanation into an objective truth.
3. Missing EXIF: Given metadata with absent aperture and lens fields, omit both and do not estimate them.
4. Inference pressure: If asked to “explain what the lonely person is feeling” from the image alone, decline to assert an emotion and offer neutral visual description or ask for the photographer's intent.
5. Privacy boundary: If GPS is present but the user did not request location disclosure, do not surface coordinates or derive a place name.
6. Camera JPEG: For a camera file whose exposure fields sit in the Exif sub-IFD (tests/fixtures/photo-caption-writer/camera-subifd.jpg), every field of extract_exif.py is non-null and the file's GPS is not printed.
7. Export time only: For a file with only IFD0 DateTime (export-datetime-only.jpg), captured_at is null; state no capture date and ask for one if the caption needs it.
8. HEIC: For IMG_0001.heic, the script exits 1 with the sips command; convert or ask, never guess the settings.

Full cases: tests/cases/photo-caption-writer.md.

变更记录 / Changelog

版本	日期	变更	类型
0.1.1	2026-09-26	extract_exif.py 改用共享的 image_io.py 读 Exif 子 IFD，相机 JPEG 的光圈、快门、ISO、焦距、镜头、拍摄时间不再全是 null；拍摄时间只取 DateTimeOriginal；新增 camera、focal_length_35mm 两个键和 --selftest；写明 HEIC 先用 sips 转 JPEG；description 前加中文触发语；示例命令改用 python3	patch
0.1.0	2026-09-09	初始版本	minor