On 10/2/14, Brian Wolff <bawolff@gmail.com> wrote:
> Hi everyone.
>
> tl;dr: Can we do https://gerrit.wikimedia.org/r/164476
>
> Now that the pre-requisite patches for using VIPS with tiff has been
> merged (Woo!), lets umm use it.
>
> So for those who don't know what vips is, vips is an alternative to
> image magick which can scale certain file formats in essentially
> constant memory (Or probably to be pedantic, linear in the number of
> pixels in the resulting file, instead of linear in the number of
> pixels in the source). This means we would be able to make thumbnails
> no matter how big the source file is. Which is good because we have
> lots of very high resolution tiff files, such as [[File:Zoomit2.tif]]
> and [[File:Zentralbibliothek Zürich - Mittelalterliche Stadt -
> 000005203.tif]]. We already use VIPS to scale png files larger than 20
> megapixels, and non-progressive jpeg files can be scaled efficiently
> with image magick, so tiff is the current pain point in terms of
> scaling limits (although GIF is also painful).
>
> I would like to propose the following:
>
> First we experiment with turning it on for files > 50 megapixels.
> Currently we do not even try to render such files, so I doubt this
> will cause any community angst. To that end I proposed a patch (
> https://gerrit.wikimedia.org/r/164476 ) that uses the following
> settings:
>
>                array(
>                        'conditions' => array(
>                                'mimeType' => 'image/tiff',
>                                'minShrinkFactor' => 1.2,
>                                'minArea' => 5e7,
>                        ),
>                        'sharpen' => array( 'sigma' => 0.8 ),
>                )
>
> This will turn the feature on for big files (which currently do not
> render), and also enable sharpening (Most tiff images benefit from it
> and the community has asked for it repeatedly, I think its less
> disruptive to enable sharpening at the same time as VIPS, instead of
> two separate changes to tiff rendering).
>
> I would propose we let that sit for a little bit. We should than have
> a community discussion (With the commons community, since its hard to
> have a discussion with every community, and commons (+esp. Glams) are
> the people who care the most about this) to see if the community likes
> that. Hopefully if all is well we could move to stage 2, which would
> be something like:
>
>                array(
>                        'conditions' => array(
>                                'mimeType' => 'image/tiff',
>                                'minShrinkFactor' => 1.2,
>                        ),
>                        'sharpen' => array( 'sigma' => 0.8 ),
>                ),
>                array(
>                        'conditions' => array(
>                                'mimeType' => 'image/tiff',
>                        ),
>                ),
>
>
> Anyways, thoughts. Does this sound like a good plan? Someone want to
> be bold and deploy my change ;)
>
> --bawolff
>

This is live now. First results look promising, however some images
don't seem to be working

*Really big images (>350 megapixels) seem to run into a timeout
(especially lzw compressed images, but that could be a coincidence,
very small sample size)
*https://commons.wikimedia.org/wiki/File:Carr_wilbur_j_honorable.tif
and https://commons.wikimedia.org/wiki/File:Amelia_earhart_received_by_president_coolidge.tif
are broken. Not sure what the deal with those two are yet. They do not
appear broken (locally anyways) if converting directly instead of
using intermediary step. Random theory is something to do with colour
profiles as they're both greyscale images, but needs further
investigation.

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