The Google Image Search server - https://www.google.com/imghp - can handle transparent images uploaded via the page UI, but the built-in search command sends a JPG thumbnail [1] of the image to the server, completely ignoring the transparency of the image thus mangling the result. This has always worked this way since 2013 when the feature was added [2].

Some thoughts:
* There should be no need to re-encode small images such as the reported png because the resultant jpg may easily have a larger file size.
* In case re-encoding is unavoidable and the image has transparency, it would make sense to force a white background color.
* WebP encoder supports lossy mode with transparency would be a better choice - if the encoder is built-in.

  [1]: https://cs.chromium.org/chromium/src/chrome/browser/ui/tab_contents/core_tab_helper.cc?l=119&rcl=55afbe42e3931c4835c53104ea805e41ac8e0f18
  [2]: https://chromiumcodereview.appspot.com/21323003/diff/88001/chrome/browser/renderer_host/chrome_render_view_host_observer.cc#pair-216

Thanks for filing the issue!

Able to reproduce the issue on reported chrome version 66.0.3359.181 and on the latest canary 68.0.3436.0 using Ubuntu 14.04, Mac 10.13.1 and Windows 10.  As the issue is seen from M60(60.0.3112.0) considering it as Non-Regression and marking it as Untriaged.
Note: Tentatively adding component "UI>Browser>Search", please change if this isn't apt.

woxxom@,

is there a component we can assign this bug to so it won't be lost?  Or at least some explicit CCs?  This doesn't feel like an ordinary UI>Browser>Search bug...

IDK, I've only checked the source code. Maybe UI>Browser>Contextual>Search in addition to the existing component.

CCing some people who touched relevant code recently; maybe they know who owns this / can improve this