EXIF Viewer & Editor

Introduction:

Image metadata, often called photo metadata, is the structured information embedded inside pictures. The Exchangeable Image File Format (EXIF) defines common tags for camera settings, capture time, and optional location. Use it to view and edit photo EXIF metadata while keeping pixels unchanged. These tags travel with the image across apps and devices, which is helpful for organizing, auditing, and sharing responsibly.

You provide a picture, the utility reads its tags and returns human‑readable fields, a map when coordinates exist, and a JSON view you can copy. Outputs are new images created from the original pixels, with optional rotation applied to make them upright. You choose how metadata is handled, either removed, carried over from the file, or replaced by your edits.

Imagine a vacation shot reporting f/1.8, 1/120 s, ISO 64, and coordinates near 48.8584 2.2945. You might correct the date, clear the artist field, or remove GPS before sharing with a group. Metadata can reveal sensitive context. Share images only when you’re comfortable with the information they contain.

Technical Details:

The tool inspects Exchangeable Image File Format (EXIF) records directly in your browser. It parses tags for camera make, model, lens, exposure, aperture, ISO, focal length, orientation, and optional GPS coordinates. If coordinates are present, the UI renders a map pin for quick verification. Exporting redraws pixels onto a canvas, optionally applying the orientation so output pixels are upright. For JPEG, a curated tag set can be re‑embedded or authored from your edits; PNG and WebP export without metadata. Processing is deterministic and client‑side, with no server round trips.

Core processing pipeline

1. Validate that the selected file’s MIME type starts with image/.
2. Decode the image and record width, height, and file size.
3. Parse EXIF and GPS tags, prefill editable fields, and count detected tags.
4. Show a map pin when both latitude and longitude are finite numbers.
5. On export, choose output format and quality based on your selections.
6. Redraw onto a canvas, applying EXIF orientation when auto‑rotate is enabled.
7. For JPEG with “Keep” or “Apply edits”, build a new EXIF object and set Orientation=1.
8. Encode the image; for JPEG re‑embedding uses a data‑URL path, others use blob encoding.
9. Create a blob URL, compute output size, and prepare a downloadable filename.

Symbols & Units

Variables & parameters

Units, precision & rounding policy

• Decimal separator is a period; displayed values are locale‑neutral.
• File sizes show two decimals in kilobytes; exposure ≥1 s shows three decimals.
• Aperture shows one decimal; focal length rounds to the nearest integer.
• Coordinates display to six decimals; altitude shows one decimal when edited.
• Rounding follows JavaScript toFixed semantics (IEEE‑754 round‑to‑nearest; ties may appear even due to binary representation).
• In JPEG EXIF, GPS seconds and altitude are encoded as rationals with a denominator of 100.

Validation & bounds extracted from code

I/O formats & encoding

*GPS is written only when both latitude and longitude are finite. PNG and WebP exports do not include EXIF.

Networking & storage behavior

• All image parsing and export occur locally in your browser.
• Map tiles are requested from a public tile service when the map tab is opened and GPS exists.
• No server‑side storage; JSON and CSV are generated in memory for download or clipboard use.
• Temporary blob URLs are created for previews and downloads; they are revoked on reset.

Performance & complexity

• Parsing and redraw scale linearly with image pixels and metadata size.
• Exporting via data‑URL for JPEG briefly duplicates image data in memory.
• Map rendering is lightweight and only initialized when the map tab is active.

Diagnostics & determinism

• Error messages include: could not load image, failed to read metadata, and export failed.
• “Copied!” states confirm clipboard actions for CSV, JSON, and output URL.
• For identical inputs and selections, outputs are deterministic.

Security considerations

• EXIF may reveal location and device details; clear sensitive tags before sharing.
• Only open images from sources you trust.
• Map tiles load from the internet; no image content is uploaded.

Worked example

Assumptions & limitations

• Only JPEG exports can include EXIF; PNG and WebP export without metadata.
• Heads‑up “Keep” writes a curated subset, not every original tag.
• Heads‑up Advanced toggles for GPS scrubbing, rounding, and digitized time are present but not applied during export.
• EXIF Orientation is always set to 1 on JPEG export.
• Quality control does not affect PNG; browsers may limit supported output MIME types.
• Date edits use local time; seconds are not captured in the edit field.

Edge cases & error sources

• Corrupted or unsupported EXIF may prevent tag parsing.
• Very large images can exceed memory during data‑URL generation.
• Images without both latitude and longitude will not show a map.
• GPS values outside allowed ranges are rejected on save.
• Non‑numeric date strings are rejected on save.
• Floating‑point rounding may surprise near half steps (for example, “.005”).
• Choosing “Auto” for formats unsupported by the encoder may fallback to a default.
• Clipboard actions require browser permission and may be blocked by policy.

Scientific/standards backing

• Exchangeable Image File Format (EXIF) tag structure and fields.
• WGS84 latitude and longitude for GPS coordinates.
• ISO 8601 date and time representations for display parsing.

Privacy & compliance

Files are processed locally in your browser; no data is transmitted or stored server‑side. Map tiles are requested from an external service solely for display. Remove sensitive metadata before sharing when privacy obligations apply.

Step‑by‑Step Guide:

Follow these steps to inspect, edit, and export safely.

1. Select a photo that reports as an image MIME type.
2. Review details and, if needed, switch to the map or JSON tabs.
3. Edit fields such as Make, Model, Description, Artist, Date, or GPS.
4. Pick Export format and adjust Quality for lossy types.
5. Choose a Metadata mode: Strip, Keep, or Apply edits.
6. If in doubt, strip GPS before sharing.
7. Export and download the new image.

Example: Set format to JPEG, quality 92%, auto‑rotate on, mode “Apply edits”, then export and download the JPEG with your updated tags.

• Tip: Use CSV or JSON export to archive original and edited values together.

You now have a share‑ready image with the metadata handling you selected.

FAQ:

Troubleshooting:

• “Unsupported file type” → Pick a file whose MIME starts with image/.
• No map shown → Ensure both latitude and longitude are present and valid.
• “Failed to read EXIF metadata.” → The file may have corrupted tags; try another copy.
• “Export failed.” → Reduce image size or switch format to PNG.
• Clipboard blocked → Allow clipboard permissions in your browser settings.

Advanced Tips:

• Tip Use “Apply edits” with JPEG to author a minimal, privacy‑aware tag set.
• Tip Strip metadata for screenshots and illustrations to keep files lean.
• Tip Prefer PNG when exact pixel fidelity matters more than file size.
• Tip Use JSON export to diff metadata before and after edits.
• Tip When sharing widely, remove GPS unless location adds clear value.

Glossary:

EXIF

Standardized tags embedded in image files for capture and device details.

GPS IFD

The EXIF section that stores latitude, longitude, and altitude.

Orientation

EXIF tag indicating how pixels should be rotated for correct display.

DMS

Degrees, minutes, seconds representation of geographic coordinates.

Blob URL

Temporary browser URL that references in‑memory binary data.

Data URL

Inline base64 representation used here to embed JPEG metadata.

MIME type

String that labels the format of a file, such as image/jpeg.