Image Toolbox

★★★★☆

An extremely powerful image editor for Android. And not just the usual features like crop, adjust contrast or brightness, maybe apply a filter, but you can do batch edits, format conversion, scaling the actual pixel image, editing metadata…all the things that mobile apps tend to hide behind the curtain (because why would someone need to even know the pixel depth, never mind change it? :eyeroll:). The downside is that it’s a bit awkward to use.

So far this is the only image editing app I’ve tried on Android that I can get to keep both location and timestamp EXIF data intact when editing. Sometimes. It seems to keep all EXIF data if you start with “single edit,” but drops at least location if you start with “crop.” Within a single edit, you can make a lot of adjustments, including cropping, arbitrary rotation, saturation, etc. and it’ll preserve the metadata.

I’m still getting a sense of where things are and which controls will get me the effect I want, which is usually cropping and adjusting the contrast for iNaturalist. That’s why I really want to be able to make these edits without losing or altering the EXIF data: the location and timestamp matter for the observation.

Google Play vs. FOSS Variants

The version in the Play store uses Google’s machine learning for some features, as well as Google’s crash reports and other analytics. It can also be built as capital-F Free software, without the telemetry and Google-dependent features, making it suitable for F-Droid’s stricter requirements (though there’s a bug keeping the latest release out of F-Droid).

On Preserving Metadata

You’d think “don’t change the stuff that the user isn’t changing” would be a low bar, but most image editors I’ve used on Android handle EXIF data in one of three ways:

• Treat EXIF as junk and throw it away haphazardly, often including the time a photo was taken! (At least Fossify Gallery considers this a bug.)
• Remove some or all metadata, including location, for privacy reasons. (Scrambled EXIF is great, but it removes everything.)
• Preserve metadata, but with bugs. (For instance: Google Photos forgets the time zone if you’re not syncing with their cloud, so I ended up with photos stamped with the right location, but the time off by the difference from UTC and I’d have to use a desktop anyway to fix all the timestamps. And while Sly has an option to save metadata, it doesn’t seem to work.)

I still haven’t sorted out all the circumstances under which Image Toolbox keeps or discards it, but at least I’ve found something for the specific phone-to-iNat workflow.