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EXIFメタデータ解析・撮影情報とGPS位置情報の確認
EXIFメタデータ解析・撮影情報とGPS位置情報の確認
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コアアーキテクチャ & 計算式
Image Buffer ➔ Parse TIFF Header ➔ Extract IFD (Image File Directory) Tags ➔ Decode ASCII/Rational
EXIF data is not standard text; it is stored in structured binary directories (IFDs) directly after the JPEG start marker. The parser reads these hex offsets to translate the binary into readable strings (like 'Apple iPhone 14').
ベストプラクティスとガイドライン
- Check for GPS Coordinates: Modern smartphones tag photos with exact latitude and longitude by default. Never upload a raw photo taken inside your home to a public forum or social media site without verifying the GPS data is stripped.
- Analyze Exposure Triangle Data: EXIF is an incredible learning tool for photographers. You can analyze the Shutter Speed, Aperture (F-Stop), and ISO of professional photos to understand exactly how the shot was achieved.
- Understand Social Media Scrubbing: Major platforms like Instagram and Twitter automatically strip EXIF data upon upload to protect user privacy. However, smaller forums or personal blogs usually do not, leaving your location data fully exposed.
よくある質問 (FAQ)
Does PNG support EXIF data?
Historically no, though recent updates to the PNG specification allow for an EXIF chunk. However, 99% of EXIF privacy leaks occur via JPEG files taken directly from smartphones.
Can EXIF data be faked or altered?
Yes. EXIF data is just unencrypted binary tags. Anyone with a hex editor or a metadata manipulation tool can easily change the 'Date Taken' or fake the GPS location to anywhere in the world.
Why does my photo not have any EXIF data?
If you downloaded the photo from a major social media platform, or if the photo was heavily edited and saved for the web via Photoshop, the EXIF metadata was likely deliberately stripped during that process.