Wikipedia app or Gmail doubles Wiki image sizes when sharing them

Question

I am sharing a lot of images and articles from mobile Wikipedia app to my Gmail account. Today I noticed that either app itself or Gmail is doubling image sizes during this course of action.

For example, I stumbled across this image.

Corresponding Wikipedia page says:

500 × 373 pixels. No higher resolution available

I shared it to my email address the usual way (using three dot > Share) and when received shared email in my Gmail it turned out that the image has 1280 x 955 pixel dimensions. So it is two and a half times bigger than the original one.

As you can see above, the image itself is very blurred and artificially oversized. So, it is not Wikipedia hiding some actually bigger image resolution. It is either Wikipedia app or Gmail doubling image during share process.

Is this some weird feature that I don't understand? Or is this a bug introduced in Wikipedia mobile app?

Answer 1

This is because the Wikipedia app actually requests a fixed 1280px-width image when viewing it in the in-app gallery and sharing it from there.

When an image is tapped, the app allows the user to view the image in a special viewer (a.k.a. in-app gallery). The image shown in the gallery is actually a resized image.

For this specific image, the URL is

https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Kraszewski_manor_in_Do%C7%94haje%2C_drevaryt.Jpg/1280px-Kraszewski_manor_in_Do%C7%94haje%2C_drevaryt.Jpg

Note the 1280px in the middle of the URL. This link is actually an API for generating an image thumbnail with arbitrary width so that it is possible for Wikipedia/Wikimedia Commons to generate a smaller/larger image than the original when needed.

When tapping the "Share" button, the app uses the image directly from the in-app gallery (which has been resized) and stores it locally as a temporary file for the purpose of sharing, which is why the width is always 1280px when shared.

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One known possible workaround is to download the image first since it is using the original URL, and thus getting the original image with the original size.

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Since the official Wikipedia app is open-sourced:

• For end-users: feel free to file an issue for this to discuss if this is a bug or by design, and to let them know the user's expectation.
• For developers: it is possible to modify the behavior of image sharing. The relevant code should be inside GalleryItemFragment.shareImage() for determining the source of the image and GalleryActivity.onShare() for the filename.