{% extends "calibration/base.html" %}

{% block content %}
<h1>Upload calibration pictures</h1>

<p>So you want to use lens correction features of Darktable, Rawstudio,
digiKam, Imagemagick etc, but your lens is not yet supported</a>?  No problem –
just take some test shots and upload them here.</p>

<h2>How to upload</h2>

<p>First, <a href="/lensfun_coverage.html">check whether the data is already
    available in current Lensfun</a>!</p>

<p>Then, read carefully the section <a href="#instructions">“How should test
shots look like?”</a>  below.</p>

<p>Please select a tarball (.tar.gz) or a ZIP file from your computer that
contains the RAW pictures.  A single upload may contain RAWs for many different
lenses, but only <em>one</em> camera.</p>

<p><strong>Important:</strong> By uploading files here, you thereby grant
me, <a href="mailto:{{ admin_email }}">{{ admin_name }}</a>, the
right to permanently store them on my computer and use them for generating
calibration data.  This data is then published under the
  <a href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons
Attribution-Share Alike 3.0 license</a>.  I may make your images anonymously
available to open source projects, e.g. to exiv2 in order to improve automatic
lens model detection.  I will never publish or give away your email
address.</p>

<form enctype="multipart/form-data" method="post">
  <table border="1">
    {{ upload }}
  </table>
  <p><input type="submit"/></p>
</form>

<hr/>

<h2>What happens after the upload?</h2>

You receive an email with the acknowledgement and a link to the GitHub issue
that tracks your upload.  After processing, I will send you an email with
instruction for how to install them locally.  At the same time, your data is
included into the Lensfun project.  Please give us time for this.  You can
accelerate this process
by <a href="https://github.com/lensfun/lensfun/blob/master/tools/calibration_webserver/workflow.rst">becoming
a calibrator</a> yourself.

<img style="float: left; margin-right: 1em; margin-top: 3ex; margin-bottom: 3ex"
     src="/lens_calibration_tutorial/hugin_half.png" alt="Good anti-distortion target"/>

<h2 id="instructions">How should test shots look like?</h2>

<p>If you calibrate a zoom lens, take pictures at at least five different focal
lengths.  Always include the extreme values.</p>

<p>Test shots need to be taken at a distance of at least 5 metres.  The
pictures must contain one straight line, running from one end of the picture to
the other, very close to the long border of the picture.  Ideally, it contains a
second straight line 1/3 of the image height from the top.</p>

<p>The picture on the left is a good example.  The numbered marks follow the
two lines that I mentioned.  I recommend that you use a modern building and
take pictures of it.  Don't take picures of brick walls or tiles.  Tilting or
rotating the camera is allowed.  Make really sharp pictures.  Switch off all
corrections (some cameras do this even for RAWs).</p>

<p>I have compiled <a href="/calibration/target_tips">three further sample pictures</a>,
to eliminate all doubts.</p>

<img style="float: right; margin-left: 1em"
     src="/lens_calibration_tutorial/DSC03194.jpg" alt="Good TCA correction target"/>

<h2 style="">TCA and vignetting</h2>


<p>The more corrections are possible, the better.  As for TCA (chromatic
aberration), I can maybe use the same pictures that you uploaded for distortion
above.  Anyway, they need to contain sharp high-contrast edges over the whole
image, see the photo on the right.</p>

<p>As for taking pictures for vignetting correction,
see <a href="http://wilson.bronger.org/lens_calibration_tutorial/#id3">my lens
calibration tutorial</a>.</p>

<h2>About EXIF data …</h2>

<p>I need to know lens model, focal length, and aperture for each shot.
Mostly, this is already included in the RAW.  In case it isn’t, you will be
pointed to a web page where you can add any missing data.</p>

<p>However, if the EXIF data in some files is plain wrong (for example, you
used a fisheye converter), it is necessary that you rename such files.  For
example, you may rename to</p>

<pre>    Canon_EF_24-70mm_f__2.8L_USM--35mm--2.8.CR2</pre>

<p>In the lens name, a single underscore “_” represents a space “ ”, and double
underscore “__” represents a slash “/”.</p>

{% endblock %}
