PassReal vs ExifTool: which one do you need?

If you only need to remove metadata from a file, ExifTool is enough, and it is the more precise tool. PassReal does that too, but it also re-encodes the pixels, adds sensor-style grain and writes a coherent camera profile. Choose it when the file's pixels matter as well, or when you would rather not use a command line.

Last updated: 2026-10-08

What each tool is for

ExifTool is a metadata tool. According to its own site it reads, writes and edits meta information in a very wide range of file types, and it ships as a Perl library plus a command-line application, with a Windows executable and a macOS package. It does one thing and does it precisely: it touches tags and leaves the image data alone. The project's FAQ describes editing a file with it as lossless as far as the image is concerned.

PassReal is an image pipeline. It removes metadata too, but it does so by rebuilding the file from decoded pixels, and then it changes the pixels themselves in a few documented ways. Those two designs answer different questions, and the honest comparison is to ask which question you have.

Where ExifTool is simply better

If your question is "delete the GPS position and the camera serial number from this photo", use ExifTool. It can delete a single group or a single tag, copy tags from one file to another, and leave everything else byte for byte as it was. PassReal cannot do a surgical edit: it always rebuilds the whole file.

ExifTool also supports far more formats than PassReal, which accepts PNG, JPEG and WebP only, up to 20 MB and 8192 pixels on the longest side. If you are working with RAW files, TIFF, video or PDF, PassReal is not an option, and the ExifTool documentation itself warns that some formats, RAW among them, should not have all of their metadata removed.

Finally, ExifTool is a tool you run on your own machine. Nothing is uploaded. For a sensitive photograph that matters. PassReal processes files on a server, so for private material the local tool is the safer default.

What a metadata-only pass leaves behind

Dropping tags is only half of what a generated image carries. A metadata pass does not touch the pixels, so whatever statistical signature the generator left in them stays. It also leaves a file with no camera data at all, and cameras and phones always write EXIF, so an image with none is unusual among photographs.

A few specifics are worth knowing if you use ExifTool for this job:

• -all= removes color space information as well, which the documentation says may affect colors. The FAQ shows a variant that keeps the ICC profile and restores the EXIF color space tags.
• ExifTool writes a backup named with an _original suffix unless you pass -overwrite_original, so a folder of results can double in size.
• C2PA manifests are not rewritten. They can be deleted from supported types by removing the JUMBF group, and after that you should re-read the file to check that the removal worked.
• MakerNotes are described as permanent in the documentation: they can be edited but not created or deleted individually.

None of these are flaws. They are the edges of a tool that is designed to edit metadata, not to make an image look like it came from a camera.

What PassReal adds

PassReal runs four stages that are switched on today. It strips the metadata by re-encoding from a pixel array, it simulates a sensor, it smooths the frequency spectrum with an FFT filter, and it encodes a JPEG with EXIF taken from a consistent device profile and a matching quantization table. Two more stages exist in the code and are switched off, because measurements showed no gain.

The sensor step adds grain and a small lateral chromatic aberration that is zero at the center and larger at the corners, as a real lens would produce. The profile step writes a make, model, lens data and capture settings that agree with each other, so the file does not carry the empty EXIF block that a plain strip leaves.

After processing, the interface shows a provenance report: how many markers the file carried before, grouped by family such as C2PA, XMP, EXIF and IPTC, and how many remain. On a Gemini export, 174 markers went down to 0. That is a statement about declared provenance, and it is the thing the product really does.

What neither tool does

Neither tool makes an image impossible to detect. A classifier reads pixel statistics, and our own measurements show that processed images can still score high on public detectors: ZeroGPT returned 0.96 to 0.97 after processing. Both tools remove what an image says about itself. Neither changes what the image shows, and an implausible subject stays implausible.

SynthID is a separate case. It is a watermark written into the pixels by Google tools, and Google describes it as designed to survive cropping, filters and lossy compression. Removing metadata, with either tool, does not target it, and we do not guarantee that processing removes it.

A quick way to decide

• You want to delete a few tags from your own photo: ExifTool.
• You need to process RAW, TIFF, video or PDF files: ExifTool.
• The file is private and must not leave your machine: ExifTool.
• You have many generated images and want new pixels plus a camera profile without writing commands: PassReal.
• You want a report of what provenance data the file carried before and after: PassReal.

The two are not rivals. Many people end up using ExifTool to inspect a result with exiftool file.jpg and PassReal to produce it.

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