Most mature social networks do remove this information to prevent users accidentally sharing their locations. Can someone positively say whether Lemmy is aware enough to strip extra information from photos?
I'll have a look at this when I get a sec. I know the images are re-processed on upload (and cropped etc) so I assume no useful data is preserved in that process. Good to confirm tho
Looking in ImageRepository.php it doesn't appear that images have their extra data stripped. Also testing it on my dev instance showed that GPS data remained in the image. Should be an easy fix since all image uploads are processed through that repository.
“I have just tested by uploading/re-downloading an image, and the EXIF data is removed. I then looked through the Lemmy issues and found this issue related to the image-uploading back-end (pict-rs) removing the EXIF data. In response to this issue, the developer of pict-res (asonix) comments that striping the EXIF data was one of the original motivations for building the uploader. I am not sure about how to search through the source code of pict-rs, and it seems like this step is not properly documented in the readme file, so I have not been able to find exactly where the metadata removal operation takes place. I think that this is done by invoking ‘exiftool’.”
You could check by downloading a bunch of photos and looking at the exif data, I suppose. Someone said the other day it isn’t, which would be definitely a problem. It’s also possible a specific instance could not strip it, which is worth checking for your own photos. I noticed that photos seem to retain the original filename which is not optimal.
Exactly. Even if the standard Lemmy software does it, there’s no guarantee that your instance admin hasn’t altered the code or done something else to keep that data.
I’m hesitant to name anything specific since time exists and tech fluctuates, but there’s definitely a small, free utility app for your device that will strip exif data from your images.
Search for ‘remove exif’ in your App Store and see what people are saying about the top several apps listed.
(EtA: In nongeek, ‘exif’ data includes the photo’s gps coordinates, specific type of camera or device that created the image, timestamp, and other info, and its all quite easily viewable.).
Nerds use these apps more than most, so their reviews tend to go into some detail. There are certainly apps available that are easy to use on your device. Obviously don’t use an online service for this, either.
I load an image into Gimp, scale it to a smaller size and export it with EXIF and XMP removed. Make sense also since devices these days create 3200x3200 images which is unnecessarily large for uploading.
No no not needless. I haven’t looked into it past what I’ve seen while lurking. I’m putting together a workstation for SD, but have only used cloud instances so far and haven’t tried to use the embedded prompt. I merely noted it exists. Now I have something else to look up and reference. Thanks.
Basically the PNG file format is a series of chunks. The most useful being the IDAT chunk which is the image data. IHDR has the info about the resolution too. Everything else can be removed and it should work the same as far as viewing is concerned. EXIF and TEXT are just two other chunks. I believe EXIF is for information about the camera. It seems useful for photographers. TEXT is just meant for any textual data you want to put into the image.
This is a python tool I was making recently to do this which is why it is all so fresh on my mind. There seem to be tools on webpages to do it too but I don’t know how well they work. Here is one. They are probably easier to get going.
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