[QA] resizing big images will get faster next week

[Željko Filipin]

On Tue, Jul 16, 2013 at 8:03 PM, Greg Grossmeier <greg at wikimedia.org> wrote:

> Right now the plan is to turn Vips on for PNGs over a certain size (see
> https://bugzilla.wikimedia.org/show_bug.cgi?id=51370 ). Everything else
> stays the way it is. We could enable more image size/types later as
> VipsScaler is improved, but not yet.
>
> We could get a suite of images of various sizes that are expected to be
> scaled using Vips (within that limit suggested by Brian on bug 51370),
> if we get an error instead of a valid png, then it's broken (probably
> because of an OOM).
>
> Is this something that could be done?
>
> If it is, then we should have a bunch of known good images of various
> sizes/types (png, jpg, gif, etc) that we throw at it to make sure we
> don't break anything as we move forward with more Vips changes.
>

This sounds to me like a perfect candidate for an automated test. If you
can provide (links to) images that are good for the test, I can write code
that will upload/thumbnail the images. We can pair on that next week. Or we
could generate big images (there are libraries for that, I am sure).

The tricky part is checking if "anything looks wrong". Computers are bad at
that.

Solution #1: There are libraries for comparing images, we could try one of
them. For example, are these two images exactly the same (comparing pixel
by pixel)? Should we tolerate up to 1-2% of pixels being different?

Solution #2: The test creates a report (HTML page, for example) displaying
original image, uploaded image, thumbnail (...) side by side, so a human
could in a minute or two scan a lot of images and see if anything looks
strange.

Željko
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.wikimedia.org/pipermail/qa/attachments/20130717/60a606fb/attachment.html>