What Metadata Is in the File, and When Should You Strip It?

The useful metadata in these PNGs is the color tag, if one exists, and the pixel size, which is always 3840x2160. Everything else is optional text: a title, a keyword list, an XMP block, maybe a software stamp. Keep the color tag. Strip the chatter when a client intake forbids unidentified XMP, when you do not want your working path in the file, or when a CMS indexes description fields you never meant to publish.

Do not strip blindly as a ritual. A file with no sRGB tag is still sRGB by the rule on the color-space page, but some RIPs then guess. If you strip, write sRGB back, or convert in a color-managed app and export a tagged copy.

What is actually inside a PNG

PNG is a stack of chunks. The ones you will meet on a work file:

• IHDR holds width, height, bit depth and color type. This is not "metadata" you strip. If it says 3840, 2160, 8-bit, RGB, you have the right master.
• sRGB or iCCP holds the color assumption. Keep it. If both are missing, assume sRGB anyway.
• gAMA and cHRM sometimes travel with sRGB. Leave them unless a tool complains.
• tEXt, zTXt and iTXt are key-value strings: Title, Author, Description, Comment, Software, sometimes a warning. This is the first place a leftover phrase shows up.
• eXIf is an EXIF dump. More common on camera JPEGs than on these plates, but a round trip through Photoshop can create one.
• iTXt or a sidecar-like XMP packet may carry IPTC Core fields (title, keywords, copyright, creator). Photo tools love this block. Client security tools hate surprise XMP.

This archive is a still-image library, not a camera roll. You should not expect GPS, lens model or a shutter speed. You should expect, on some files, a title that matches the public page and a keyword list that matches the tags. That is convenient in a local catalog. It is inconvenient when a bank's media intake flags "unknown XMP" and rejects the upload.

Photoshop's File Info, ExifTool and pngcheck all see different slices. Trust ExifTool when you need a full dump:

exiftool -a -G1 -s slug-3840x2160-srgb.png

You are looking for XMP, IPTC, EXIF, and any text chunk that contains a path like C:\Users\ or an old job name. Pixel size should stay 3840x2160 after any strip. If it changes, you ran the wrong tool and resampled.

When to strip, when to leave it, how to do it

Leave metadata on the library master if you are the only one using the disk. Keywords make Bridge and Photo Mechanic searchable. A title beats a hash.

Strip, or replace, before these exits:

• A client security questionnaire that says "no embedded metadata."
• A packaging vendor that auto-prints IPTC titles on contact sheets.
• A public Git or marketing ZIP where Author would name a freelancer who does not want that.
• A moment you pasted a confidential project name into File Info at 1 a.m.

A clean, boring command that removes textual bags and keeps pixels:

exiftool -overwrite_original -all= -tagsfromfile @ -icc_profile -png:sRGB slug-3840x2160-srgb.png

If ExifTool drops the sRGB chunk on your build, write it back or reopen in Photoshop, assign sRGB IEC61966-2.1, and Save As a new PNG. Then check dimensions. Then check file size: a 12 MB plate should not become 800 KB unless you accidentally exported a preview.

Other tools: pngcrush -rem alla -reduce is aggressive and can drop color. ImageMagick mogrify -strip is the blunt object; run it on a copy. Do not run a "compress PNG" website on a client master. Those services resample and recompress.

What not to strip: the fact of being 3840x2160, and the color interpretation. What not to add: a fake copyright line that contradicts the license, or a required-attribution claim. Attribution is optional. Putting "© you" in XMP on a sourced plate is how legal teams get letters.

If you credit Unique Live Wallpaper, do it in the readme or on a colophon, not as an IPTC Author that will pop up inside InDesign's Links panel in six months. The credit wording belongs in human-readable text.

After stripping, the file you send still follows the hand-off folder. Metadata is not a substitute for 00_readme.txt.