About

JPEG files carry metadata in APP1 (EXIF) segments defined by the TIFF 6.0 and EXIF 2.32 specifications. Stripping or corrupting this data during editing causes loss of authorship proof, GPS provenance, and timestamp chains critical for legal evidence, stock photography licensing, and digital forensics. This tool injects a standards-compliant EXIF IFD structure directly into the JPEG binary stream without re-encoding pixel data, so image quality remains at 100%. Fields follow the tag IDs from the EXIF specification: tag 0x013B for Artist, tag 0x8298 for Copyright, and the GPS IFD for coordinates encoded as rational degree-minute-second triples.

Limitation: this tool builds a new APP1 segment and replaces any existing one. Existing EXIF data (including embedded thumbnails and maker notes) will be overwritten. If you need to preserve existing tags while adding new ones, a full round-trip parser is required. Processing is entirely client-side; no image data leaves your browser.

Formulas

GPS coordinates are stored as three RATIONAL values representing degrees, minutes, and seconds. Each RATIONAL is a pair of 32-bit unsigned integers (numerator and denominator).

Decimal = D + M60 + S3600

Where D = degrees (integer), M = minutes (integer), S = seconds (may include fractional part). The tool converts a decimal coordinate like 48.8566 into the DMS rational triple stored in the EXIF GPS IFD.

The inverse conversion used internally:

Seconds are multiplied by 1000 and stored as rational S_int1000 to preserve three decimal places of precision, yielding positional accuracy of approximately 0.11m.

EXIF RATIONAL type structure per value:

[4 bytes numerator] [4 bytes denominator] = 8 bytes total

Reference Data

EXIF Tag	Tag ID	IFD	Type	Description
ImageDescription	0x010E	IFD0	ASCII	Caption or description of the image content
Make	0x010F	IFD0	ASCII	Camera manufacturer name
Model	0x0110	IFD0	ASCII	Camera model identifier
Software	0x0131	IFD0	ASCII	Software used to create or process the image
Artist	0x013B	IFD0	ASCII	Photographer or creator name
Copyright	0x8298	IFD0	ASCII	Copyright notice string
DateTime	0x0132	IFD0	ASCII	File modification date (YYYY:MM:DD HH:MM:SS)
DateTimeOriginal	0x9003	Exif IFD	ASCII	Date the original image was captured
UserComment	0x9286	Exif IFD	UNDEFINED	Free-form user comment (ASCII charset prefix)
GPSLatitudeRef	0x0001	GPS IFD	ASCII	N or S hemisphere indicator
GPSLatitude	0x0002	GPS IFD	RATIONAL ×3	Latitude as degrees, minutes, seconds rationals
GPSLongitudeRef	0x0003	GPS IFD	ASCII	E or W hemisphere indicator
GPSLongitude	0x0004	GPS IFD	RATIONAL ×3	Longitude as degrees, minutes, seconds rationals
GPSAltitudeRef	0x0005	GPS IFD	BYTE	0 = above sea level, 1 = below
GPSAltitude	0x0006	GPS IFD	RATIONAL	Altitude in meters as unsigned rational
ExifIFDPointer	0x8769	IFD0	LONG	Offset pointer to Exif Sub-IFD
GPSInfoIFDPointer	0x8825	IFD0	LONG	Offset pointer to GPS IFD
ExifVersion	0x9000	Exif IFD	UNDEFINED	EXIF version, typically 0232
ColorSpace	0xA001	Exif IFD	SHORT	1 = sRGB, 65535 = Uncalibrated

Frequently Asked Questions

No. This tool operates at the binary segment level. It locates the JPEG SOI marker (0xFFD8), removes any existing APP1 segment, and injects a new APP1 block before the remaining segments. The entropy-coded image data (SOS segment and scan data) is never decoded or re-encoded, so there is zero quality loss.

Any existing APP1/EXIF segment is fully replaced by the newly constructed one. Existing tags not present in this tool's field set (e.g., lens data, exposure settings, embedded thumbnails, maker notes) will be lost. If you need to preserve specific original tags, export them first using a reader tool before writing.

Seconds are stored with 3 decimal places via the rational pair S×1000 / 1000. This yields angular precision of 0.001 arc-seconds, which corresponds to roughly 0.03 meters at the equator. For practical purposes, the limiting factor is the accuracy of the coordinates you input, not the storage format.

The EXIF 2.32 specification (JEITA CP-3451C) mandates this exact 19-character ASCII format with colons separating date components and a space before the time. Using hyphens or ISO 8601 T-separator will cause non-compliant readers to reject or misinterpret the timestamp. This tool auto-formats your input to match.

No. PNG uses tEXt/iTXt chunks and WebP uses RIFF/XMP containers - both are structurally different from JPEG APP1 segments. This tool exclusively handles the JPEG/JFIF container format. Attempting to load a non-JPEG file will trigger a validation error.

This tool limits ASCII string fields to 256 characters each. While the EXIF spec allows longer strings via offset data, extremely long values can cause compatibility issues with certain viewers and OS file property dialogs. The UserComment field supports up to 512 characters.