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<div class="document" id="graphicsmagick-motion-picture-features">
<h1 class="title">GraphicsMagick Motion Picture Features</h1>
<!-- -*- mode: rst -*- -->
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<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#introduction" id="id1">Introduction</a></li>
<li><a class="reference internal" href="#applications" id="id2">Applications</a></li>
<li><a class="reference internal" href="#dpx-features" id="id3">DPX features</a><ul>
<li><a class="reference internal" href="#basic" id="id4">Basic</a></li>
<li><a class="reference internal" href="#colorspaces" id="id5">Colorspaces</a></li>
<li><a class="reference internal" href="#storage" id="id6">Storage</a></li>
<li><a class="reference internal" href="#yet-to-be-supported" id="id7">Yet to be supported</a></li>
</ul>
</li>
<li><a class="reference internal" href="#using-graphicsmagick" id="id8">Using GraphicsMagick</a><ul>
<li><a class="reference internal" href="#image-resize" id="id9">Image Resize</a></li>
<li><a class="reference internal" href="#annotate-image" id="id10">Annotate Image</a></li>
<li><a class="reference internal" href="#colorspace-transformation" id="id11">Colorspace Transformation</a></li>
<li><a class="reference internal" href="#modifying-an-image-in-place" id="id12">Modifying An Image In-Place</a></li>
<li><a class="reference internal" href="#creating-a-contact-sheet" id="id13">Creating A Contact Sheet</a></li>
<li><a class="reference internal" href="#animating-a-sequence" id="id14">Animating A Sequence</a></li>
<li><a class="reference internal" href="#displaying-one-image-frame" id="id15">Displaying One Image Frame</a></li>
<li><a class="reference internal" href="#viewing-a-sequence" id="id16">Viewing A Sequence</a></li>
</ul>
</li>
<li><a class="reference internal" href="#options-and-attributes" id="id17">Options And Attributes</a><ul>
<li><a class="reference internal" href="#command-options" id="id18">Command options</a></li>
<li><a class="reference internal" href="#dpx-attributes" id="id19">DPX Attributes</a></li>
</ul>
</li>
</ul>
</div>
<div class="section" id="introduction">
<h1><a class="toc-backref" href="#id1">Introduction</a></h1>
<p>Features have been added to <a class="reference external" href="index.html">GraphicsMagick</a> 1.2 (and later) to make it
more suitable for processing images used by the motion picture (film and
high-definition) industry. In particular, industrial strength support for
<a class="reference external" href="http://www.smpte.org/">SMPTE</a> DPX Version 2.0 (<a class="reference external" href="http://www.smpte.org/">SMPTE</a> 268M-2003) has been added for
<a class="reference external" href="index.html">GraphicsMagick</a> 1.2. Legacy 10-bit Kodak Cineon is also supported. A new
logarithmic RGB space based on Kodak's Cineon log definition has been
added to support images which use a logarithmic density encoding (with
range of 0 to 2.048) according to Kodak specifications. Support for
legacy Kodak 4.5 Cineon format has been improved.</p>
<p><a class="reference external" href="index.html">GraphicsMagick</a>'s DPX support has already been put to use in the
industry. It was used to perform 16-bit TIFF to DPX conversion for
<a class="reference external" href="http://en.wikipedia.org/wiki/Christopher_Reeve">Christopher Reeve</a>'s last film "<a class="reference external" href="http://www.everyonesherodvd.com/flash/ehero.html">Everyone's Hero</a>". While this may not
be <a class="reference external" href="http://en.wikipedia.org/wiki/Christopher_Reeve">Christopher Reeve</a>'s most memorable work, the film's images turned
out great, and the kids are sure to enjoy the film.</p>
<p>The modern motion picture industry usually shoots on film and then
uses a machine known as a <em>datacine</em> (e.g. <a class="reference external" href="http://www.dft-film.com/scanners/spirit_4k.php">Spirit 4K DataCine</a> or
Cintel DSX) or a <em>scanner</em> (e.g. <a class="reference external" href="http://www.filmlight.ltd.uk/">Northlight Scanner</a> or
<a class="reference external" href="http://www.lasergraphics.com/">Lasergraphics</a> Director) to convert each film image into an
individual image file. An alternative to this is to use a high
definition CCD camera such as the <a class="reference external" href="http://www.grassvalley.com/products/cameras/viper/">Grass Valley Viper</a> or the
Panavision Genesis to capture images to uncompressed files directly. A
rather inferior approach is to use a video high definition compressed
format like HDCAM and convert each frame to a file for processing.</p>
<p>Images scanned from film are usually in either a log colorspace similar
to Cineon Log (10 bits per sample is most common), or in a linear format
(16 bits per sample is common). Some cameras (such as the <a class="reference external" href="http://www.grassvalley.com/products/cameras/viper/">Grass Valley
Viper</a>) use log encoding similar to Cineon Log. Log encoding has the
advantage that fewer bits are necessary to cover the extended dynamic
range of film, and that the log encoding approximates the density
characteristics of film (approximately linear when log encoded).</p>
<p>While there is some continued use of the legacy Kodak Cineon format due
to existing equipment and software, the standard image file format for
motion picture frames is <a class="reference external" href="http://www.smpte.org/">SMPTE</a> DPX (<a class="reference external" href="http://www.smpte.org/">SMPTE</a> 268M-2003). This format is
somewhat similar to the Kodak Cineon format, but has the advantage that
it is an industry standard rather than a vendor standard. DPX files are
practically always uncompressed. The design of DPX places header content
at fixed offsets, and the image raster data offsets may be computed, so
DPX files may be read or updated without rewriting the entire file.</p>
<p>Film images are usually captured at <em>2K</em> resolution (82 pixels/mm),
<em>4K</em> resolution (164 pixels/mm), or even <em>8K</em> resolution (328
pixels/mm), where the actual resolution values approximate the horizontal
dimension of the image. A table of <a class="reference external" href="http://www.surrealroad.com/digital/index.php/archives/2005/standard-data-resolutions/">typical pixel resolutions</a> for various
film sizes may be found on the <a class="reference external" href="http://www.digitalintermediates.org/">Digital Intermediates</a> site. File sizes may
be quite large and range in size from 8MB to as much as 180MB. The common
10-bit <em>2K</em> format consumes 12MB of disk while a 10-bit <em>4K</em> scan
consumes 50MB of disk. A typical movie has an average of 144K frames (at
24 frames per second) so just one movie consumes terabytes of storage.
Businesses which specialize in handling digital intermediates may have
available on-line storage ranging from several tens of terabytes to
several hundred terabytes. While <em>2K</em> has been the standard working
resolution due to storage requirements and processing time, recently
there is a trend to scanning at <em>4K</em> resolution since most experts say
that this is the resolution necessary to capture the full resolution of a
35mm frame (but some claim more!). IMAX film (10X the area of 35mm film!)
can likely support <em>21K</em> resolution once someone builds a machine
capable of doing so but is currently scanned at <em>8K</em> resolution. Some
shops scan at <em>4K</em> but then reduce the image to <em>2K</em> as the working
format so that the full resolution is available for later use, but the
processing of the feature may be done on a normal <em>2K</em> schedule. An
alternative is to do the work at <em>2K</em> but record a record of all the
changes so that the changes may be re-played to obtain similar results at
<em>4K</em>.</p>
<p>The end result of the effort of encoding motion picture images to digital
image files is to have a digital master which does not degrade over time
and which has captured the maximum available information from the
original film print. This digital master may be targeted toward producing
film prints for showing in a theater, used to create DVDs, used as a
master for <em>digital cinema</em> for viewing in suitably equipped theaters,
or used to support television broadcasts.</p>
<p>Processing film images is a specialty business. Many business exist which
offer specialized software and hardware to process film images. Common
tasks are <em>color grading</em> (adjusting color for a correct film print),
dust busting, and compositing. While <a class="reference external" href="index.html">GraphicsMagick</a> could (with some
effort) be used to accomplish many of these things it can never expect to
compete in these specialized areas. <a class="reference external" href="index.html">GraphicsMagick</a> lacks the high-quality
graphical user interface necessary for a colorist or artist to interact
with a sequence of images. <a class="reference external" href="index.html">GraphicsMagick</a> lacks the experienced and
dedicated team necessary to assure the desired results with particular
media.</p>
</div>
<div class="section" id="applications">
<h1><a class="toc-backref" href="#id2">Applications</a></h1>
<p>The strength of <a class="reference external" href="index.html">GraphicsMagick</a> versus specialized proprietary software
are its cost (absolutely free!), open source availability (user is able
to fix software flaws or tailor software to meet specific needs), general
purpose image processing capabilities, deep image capabilities (up to
32-bits per sample), excellent performance, platform independence, lack
of encumbering usage licenses, and robust implementation. Examples of
areas where <a class="reference external" href="index.html">GraphicsMagick</a> may be used are:</p>
<blockquote>
<ul class="simple">
<li>View the image on a display.</li>
<li>Scaling (for example, <em>4K</em> to <em>2K</em> or 1920x1080 HD with excellent quality)</li>
<li>Cropping</li>
<li>Rotation</li>
<li>Filtering</li>
<li>ICC ICM profile-based color management and transformations</li>
<li>Gamma adjustment</li>
<li>Color adjustment</li>
<li>Conversion to grayscale</li>
<li>Text annotations</li>
<li>Compositions</li>
<li>Drawing on images (for example drawing markers on image)</li>
<li>Conversion to and from other formats (e.g. Kodak Cineon, TIFF, JPEG, SGI,</li>
<li>Postscript, PNG, and PNM)</li>
</ul>
</blockquote>
<p><a class="reference external" href="index.html">GraphicsMagick</a> performs well when compared with other software. Since it
is free and portable, it may be installed on any available system with no
license fees. For example, if a studio has a computing cluster of several
hundred Linux, SGI IRIX, Solaris, FreeBSD, or Mac OS X systems, then
<a class="reference external" href="index.html">GraphicsMagick</a> may be installed across all systems and used for any
desired purpose.</p>
<p><a class="reference external" href="index.html">GraphicsMagick</a>'s DPX file format support is very comprehensive. It goes
beyond the DPX format support in other applications by striving to
implement the complete DPX specification rather than just a few commonly
used sub-formats. The capabilities of <a class="reference external" href="index.html">GraphicsMagick</a>'s DPX support are as
follows:</p>
</div>
<div class="section" id="dpx-features">
<h1><a class="toc-backref" href="#id3">DPX features</a></h1>
<div class="section" id="basic">
<h2><a class="toc-backref" href="#id4">Basic</a></h2>
<blockquote>
<ul class="simple">
<li>Anything which can be read, can also be written.</li>
<li>All DPX header information (including the user specific area) are stored as
image attributes and restored when the image is written.</li>
<li>Image source header information is updated appropriately.</li>
</ul>
</blockquote>
</div>
<div class="section" id="colorspaces">
<h2><a class="toc-backref" href="#id5">Colorspaces</a></h2>
<blockquote>
<ul class="simple">
<li>Linear RGB</li>
<li>Cineon Log RGB (default density range = 2.048)</li>
<li>Grayscale (Luma)</li>
<li>Rec. 601 and Rec. 709 YCbCr (4:4:4 and 4:2:2). Below-black and above-white
values are clipped.</li>
</ul>
</blockquote>
</div>
<div class="section" id="storage">
<h2><a class="toc-backref" href="#id6">Storage</a></h2>
<blockquote>
<ul class="simple">
<li>Bits per sample of 1, 8, 10, 12, and 16.</li>
<li>Packed, or fill type A or B for 10/12 bits.</li>
<li>All RGB-oriented element types (R, G, B, A, RGB, RGBA, ABGR).</li>
<li>YCbCr</li>
<li>Planar (multi-element) storage fully supported.</li>
<li>Alpha may be stored in a separate element.</li>
<li>Big and little endian storage.</li>
</ul>
</blockquote>
</div>
<div class="section" id="yet-to-be-supported">
<h2><a class="toc-backref" href="#id7">Yet to be supported</a></h2>
<blockquote>
<ul class="simple">
<li>Composite video.</li>
<li>Floating point formats (32 and 64 bits)</li>
<li>Depth channel (not supportable within <a class="reference external" href="index.html">GraphicsMagick</a>).</li>
<li>Studio (reduced range) YCbCr and RGB.</li>
</ul>
</blockquote>
<p>The software is written efficiently so the performance when reading and
writing files is limited by the performance of the file I/O subsystem.
The software is designed to avoid seeking while reading and writing so
that files may be read and written over pipes, or via a user provided
file descriptor.</p>
</div>
</div>
<div class="section" id="using-graphicsmagick">
<h1><a class="toc-backref" href="#id8">Using GraphicsMagick</a></h1>
<div class="section" id="image-resize">
<h2><a class="toc-backref" href="#id9">Image Resize</a></h2>
<p><a class="reference external" href="index.html">GraphicsMagick</a> is easy to use. The following is an example of scaling a
<em>4K</em> 16 bit scan to a <em>2K</em> <em>Academy</em> 10 bit image using the <a class="reference external" href="convert.html">convert</a>
command:</p>
<pre class="literal-block">
gm convert 4k.dpx -resize 1828x1556 -depth 10 2k.dpx
</pre>
<p>The above example uses the default resizing filters which are optimized
for quality, but take longer than some other filters. The <em>box</em> resize
filter provides reasonably good scaling in a reasonable amount of time:</p>
<pre class="literal-block">
gm convert 4k.dpx -filter box -resize 1828x1556 -depth 10 2k.dpx
</pre>
<p>The above example command takes about 4 seconds (on an Apple 2.5GHz G5
PowerMac or Intel 2.4GHz Xeon) to down-convert from a 131MB <em>5K</em>
(5232x4376) original 16-bit scan from a NorthLight scanner to a 11MB
<em>2K</em> 10-bit working image. Operations on more typical <em>2K</em> images
take about a quarter of a second.</p>
</div>
<div class="section" id="annotate-image">
<h2><a class="toc-backref" href="#id10">Annotate Image</a></h2>
<p>The following example shows how <a class="reference external" href="index.html">GraphicsMagick</a>'s resize capability may be
combined with its powerful drawing capability to take a full size source image
and produce a smaller (720x576) version which includes the image filename and
timecode at the top of the image, and a logo <em>bug</em> image in the bottom right
corner:</p>
<pre class="literal-block">
gm convert infile.dpx -resize '720x576!' \
-draw 'fill "white";text-undercolor "Blue";font "Helvetica";font-size 18;\
text 10,20 "%f (%[DPX:tv.time.code])";image atop 500,400 0,0 "gm-125x80t.png"' \
outfile.dpx
</pre>
<p>As may be seen, the argument to -draw can become extremely long, so to make
things easy, the drawing commands may be placed in a simple text file and
passed by reference to the draw comand:</p>
<p>First lets check what we edited into our drawing command file:</p>
<pre class="literal-block">
% cat drawcmd.txt
fill "white"
text-undercolor "Blue"
font "Helvetica"
font-size 18
text 10,20 "%f (%[DPX:tv.time.code])"
image atop 500,400 "0,0 "gm-125x80t.png"
</pre>
<p>and now we can apply it by passing the filename prefixed with a '@' to the
-draw command:</p>
<pre class="literal-block">
gm convert infile.dpx -resize '720x576!' -draw '@drawcmd.txt' outfile.dpx
</pre>
<p>The <tt class="docutils literal">0,0</tt> in the image composition command argument says to use the image as
is. If the composited image should be automatically resized, then simply
replace the <tt class="docutils literal">0,0</tt> with the desired size.</p>
<p>There are a number of powerful scripting environments for <a class="reference external" href="index.html">GraphicsMagick</a>. One
of these is RMagick (Ruby language interface to <a class="reference external" href="index.html">GraphicsMagick</a>). In Ruby, the
same effect may be obtained via a script that looks like:</p>
<pre class="literal-block">
#! /usr/local/bin/ruby -w
require 'RMagick'
include Magick
img = Image.read('infile.dpx')[0]
frog = Image.read('gm-125x80t.png')[0]
gc = Draw.new
gc.fill('white')
gc.text_undercolor("Blue")
gc.font("Helvetica")
gc.font_size(18)
gc.text(10, 20, "%f (%[DPX:tv.time.code])")
gc.composite(500, 400, 0, 0, frog, AtopCompositeOp)
gc.draw(img)
img.write('outfile.dpx')
</pre>
<p>In addition to Ruby, there are scripting interfaces for Perl, Python, Tcl, and
Ch (C-like scripting language).</p>
</div>
<div class="section" id="colorspace-transformation">
<h2><a class="toc-backref" href="#id11">Colorspace Transformation</a></h2>
<p>To convert an RGB file to a 4:2:2 YCbCr file in Rec 709 space:</p>
<pre class="literal-block">
gm convert 2k.dpx -depth 10 -colorspace Rec709YCbCr -sampling-factor 4:2:2 2k-ycbcr.dpx
</pre>
</div>
<div class="section" id="modifying-an-image-in-place">
<h2><a class="toc-backref" href="#id12">Modifying An Image In-Place</a></h2>
<p>Besides convert, which converts from one file to another, there is <a class="reference external" href="mogrify.html">mogrify</a>
which transforms the file in place. A temporary file is used (if necessary) to
ensure that the existing image file is not damaged if something goes wrong
(e.g., not enough disk space). Note that unlike some applications supporting
DPX/Cineon, when a file is modifed <em>in-place</em> , it is completely re-written.
While <a class="reference external" href="index.html">GraphicsMagick</a> makes every attempt to preserve header information, some
previously existing features of the file (such as the offset to the pixel data)
may change.</p>
<p>A typical mogrify command is</p>
<pre class="literal-block">
gm mogrify -resize 1828x1556 -depth 10 file-0001.dpx file-0002.dpx
</pre>
<p>Multiple files may be specified on the command line so the same command may
process hundreds of files in one invocation.</p>
<p>Unix users can use the find and xargs programs to perform operations on any
number of files:</p>
<pre class="literal-block">
find /assets/001 -name '*.dpx' -print | \
xargs gm mogrify -resize 1828x1556 -depth 10
</pre>
<p>Xargs works by pasting as many file names as possible on the end of the command
provided to it.</p>
<p>The GNU version of xargs provides an added benefit. It is able to run several
commands in the background. This means that if your system has multiple CPUs,
it can take advantage of all the CPUs while still using one command:</p>
<pre class="literal-block">
find /assets/001 -name '*.dpx' -print | \
xargs --max-procs 3 --max-args 25 gm mogrify -resize 1828x1556 -depth 10
</pre>
<p>The mogrify command supports the -output-directory option to sent files to a
different directory than the input files. This allows processing a large number
of files without overwriting the input files:</p>
<pre class="literal-block">
mkdir dest
cd source
gm mogrify -output-directory ../dest -resize 1828x1556 -depth 10 '*.dpx'
</pre>
<p>Note that the entire input file path specification is preserved when composing
the output path so that the input file path is simply appended to the output
directory path. Also, unless the -create-directories option is added, the user
is responsible for creating any necessary destination directories. As an
example of the path composition algorithm, if the input file name is specified
as source/file.dpx and the output directory is specified as dest, then the
output file path will be dest/source/file.dpx.</p>
<p>Here is an incantation which recursively processes all DPX files under source
and sends the result to a similar directory tree under dest.</p>
<pre class="literal-block">
mkdir dest
cd source
find . name '*.dpx' -print | xargs gm mogrify -output-directory ../dest \
-create-directories -resize 1828x1556 -depth 10
</pre>
</div>
<div class="section" id="creating-a-contact-sheet">
<h2><a class="toc-backref" href="#id13">Creating A Contact Sheet</a></h2>
<p><a class="reference external" href="index.html">GraphicsMagick</a> may be used to create a contact sheet (grid of thumbnails with
name and size) by using the <em>VID</em> pseudoformat which accepts a wildcarded
argument of files (protected by quotes!) to read. The output files are buffered
while files are being read so there is a practical limit to the number of files
which may be processed at once. To output to a Postscript file:</p>
<pre class="literal-block">
gm convert "vid:*.dpx" "contact-sheet.ps"
</pre>
<p>or to a PDF file:</p>
<pre class="literal-block">
gm convert "vid:*.dpx" "contact-sheet.pdf"
</pre>
<p>or to a sequence of JPEG files ranging from contact-sheet-000.jpg to
contact-sheet-999.jpg:</p>
<pre class="literal-block">
gm convert "vid:*.dpx" "contact-sheet-%03d.jpg"
</pre>
<p>or to a MIFF file which may be used to interactively browse the original files
using 'gm display':</p>
<pre class="literal-block">
gm convert "vid:*.dpx" "contact-sheet.miff"
</pre>
</div>
<div class="section" id="animating-a-sequence">
<h2><a class="toc-backref" href="#id14">Animating A Sequence</a></h2>
<p><a class="reference external" href="index.html">GraphicsMagick</a> may be used to animate an image sequence on an X11
display using the <a class="reference external" href="animate.html">animate</a> subcommand. Frames are buffered in memory
(pre-loaded into the X11 server) so the number of frames which may be
animated at once is limited. <a class="reference external" href="index.html">GraphicsMagick</a> has been used to animate
1080P (1920x1080) images at 24 frames per second with at least 300 frames
in the sequence.More frames may be buffered on 64-bit systems. Many more
frames may be animated by preparing a reduced set of frames in advance.</p>
<p>To visualize an animation at 24 frames per second (delay (1/24)*100) use</p>
<pre class="literal-block">
gm animate -delay 4.17 'Frame_*.dpx'
</pre>
<p>In order to obtain a preview of a larger sequence, and if the frames are
numbered, a broader span of time may be animated by selecting every 10^th frame
(terminating with zero) to animate at 2.4 frames per second:</p>
<pre class="literal-block">
gm animate -delay 41.7 'Frame_*0.dpx'
</pre>
</div>
<div class="section" id="displaying-one-image-frame">
<h2><a class="toc-backref" href="#id15">Displaying One Image Frame</a></h2>
<p>An image frame may be displayed on an X11 server using the <a class="reference external" href="display.html">display</a>
subcommand. By default the name of the image file is displayed in the
title bar. By specifying the format of the title, other useful
information such as the time code (see the DPX Attributes section for
more details) may be included in the window title:</p>
<pre class="literal-block">
gm display -title '%f (%[DPX:tv.time.code])' foo.dpx
</pre>
</div>
<div class="section" id="viewing-a-sequence">
<h2><a class="toc-backref" href="#id16">Viewing A Sequence</a></h2>
<p>A sequence of images may be displayed on an X11 server using the <a class="reference external" href="display.html">display</a>
subcommand. Unlike 'gm animate' there are no arbitrary limits when
displaying a sequence this way. Unlike 'gm animate' the inter-frame delay
can not be set to less than a second (100 ticks is one second).</p>
<pre class="literal-block">
gm display +progress -delay 100 'Frame_*.dpx'
</pre>
</div>
</div>
<div class="section" id="options-and-attributes">
<h1><a class="toc-backref" href="#id17">Options And Attributes</a></h1>
<div class="section" id="command-options">
<h2><a class="toc-backref" href="#id18">Command options</a></h2>
<p>The following command options are particularly useful when dealing with
DPX files:</p>
<dl class="docutils">
<dt>-colorspace {CineonLog|RGB|Gray|Rec601Luma|Rec709Luma|Rec601YCbCr|Rec709YCbCr}</dt>
<dd>Specifies the colorspace to be used when saving the DPX file. CineonLog
selects log encoding according to Kodak Cineon specifications. RGB selects
linear RGB encoding. Gray selects linear gray encoding similar to RGB, but
with a single channel. Rec601Luma requests that RGB is converted to a gray
image using Rec601 Luma. Rec709Luma requests that RGB is converted to a
gray image using Rec709Luma. Rec601YCbCr requests that the image is saved
as YCbCr according to Rec601 (SDTV) specifications. Rec709CbCr requests
that the image is saved as YCbCr according to Rec709 (HDTV) specifications.</dd>
<dt>-endian {lsb|msb}</dt>
<dd>Specifies the endian order to use when writing the DPX file. <a class="reference external" href="index.html">GraphicsMagick</a>
writes big-endian DPX files by default since they are the most portable.
Other implementations may use the native order of the host CPU (e.g.
little-endian when using an Intel 'x86 CPU).</dd>
<dt>-depth <value></dt>
<dd>Specifies the number of bits to preserve in a color sample. By default the
output file is written with the same number of bits as the input file. For
example, if the input file is 16 bits, it may be reduced to 10 bits via
'-depth 10'.</dd>
<dt>-define dpx:bits-per-sample=<value></dt>
<dd>If the dpx:bits-per-sample key is defined, <a class="reference external" href="index.html">GraphicsMagick</a> will write DPX
images with the specified bits per sample, overriding any existing depth
value. If this option is not specified, then the value is based on the
existing image depth value from the original image file. The DPX standard
supports bits per sample values of 1, 8, 10, 12, and 16. Many DPX readers
demand a sample size of 10 bits with type A padding (see below).</dd>
<dt>-define dpx:colorspace={rgb|cineonlog}</dt>
<dd>Use the dpx:colorspace option when reading a DPX file to specify the
colorspace the DPX file uses. This overrides the colorspace type
implied by the DPX header (if any). Currently files with the transfer
characteristic Printing Density are assumed to be log encoded density
while files marked as Linear are assumed to be linear. Hint: use
<tt class="docutils literal"><span class="pre">-define</span> dpx:colorspace=rgb</tt> in order to avoid the log to linear
transformation for DPX files which use Printing Density.</dd>
<dt>-define dpx:packing-method={packed|a|b|lsbpad|msbpad}</dt>
<dd>DPX samples may be output within 32-bit words. They may be tightly packed
end-to-end within the words ("packed"), padded with null bits to the right
of the sample ("a" or "lsbpad"), or padded with null bits to the left of
the sample ("b" or "msbpad"). This option only has an effect for sample
sizes of 10 or 12 bits. If samples are not packed, the DPX standard
recommends type A padding. Many DPX readers demand a sample size of 10 bits
with type A padding.</dd>
<dt>-define dpx:pixel-endian={lsb|msb}</dt>
<dd>DPX pixels should use the endian order that the DPX header specifies.
Sometimes there is a mis-match and the pixels use a different endian order
than the file header specifies. For example, the file header may specify
little endian, but the pixels are in big-endian order. To work around that
use -define dpx-pixel-endian=msb when reading the file. Likewise, this
option may be used to intentionally write the pixels using a different
order than the header. Files obtained from the <a class="reference external" href="http://www.digitalpreservation.gov/">Library Of Congress</a> use
big-endian 10-bit packed pixels in a file marked as little-endian so this
option must be used to read such files correctly.</dd>
<dt>-define dpx:swap-samples={true|false}</dt>
<dd><a class="reference external" href="index.html">GraphicsMagick</a> strives to adhere to the DPX standard but certain aspects of
the standard can be quite confusing. As a result, some 10-bit DPX files
have Red and Blue interchanged, or Cb and Cr interchanged due to an
different interpretation of the standard, or getting the wires crossed. The
swap-samples option may be supplied when reading or writing in order to
read or write using the necessary sample order.</dd>
<dt>-interlace plane</dt>
<dd>By default, samples are stored contiguously in a single element when
possible. Specifying '-interlace plane' causes each sample type (e.g.
'red') to be stored in its own image element. Planar storage is fully
supported for grayscale (with alpha) and RGB. For YCbCr, chroma must be
4:2:2 subsampled in order to use planar storage. While planar storage
offers a number of benefits, it seems that very few DPX-supporting
applications support it.</dd>
<dt>-sampling-factor 4:2:2</dt>
<dd>Select 4:2:2 subsampling when saving an image in YCbCr format. Subsampling
is handled via a general-purpose image resize algorithm (lanczos) rather
than a dedicated filter so subsampling is slow (but good).</dd>
<dt>-set reference-white <value></dt>
<dd>Set the 90% white card level (default 685) for Cineon Log.</dd>
<dt>-set reference-black <value></dt>
<dd>Set the 1% black card level (default 95) for Cineon Log.</dd>
<dt>-set display-gamma <value></dt>
<dd>Set the display gamma (default 1.7) for Cineon Log.</dd>
<dt>-set film-gamma <value></dt>
<dd>Set the film gamma (default 0.6) for Cineon Log.</dd>
<dt>-set soft-clip-offset <value></dt>
<dd>Set the soft clip offset (default 0) when converting to <em>computer</em> RGB from
Cineon Log.</dd>
</dl>
</div>
<div class="section" id="dpx-attributes">
<h2><a class="toc-backref" href="#id19">DPX Attributes</a></h2>
<p><a class="reference external" href="index.html">GraphicsMagick</a> provides almost full access to DPX header attributes. DPX
header attributes are shown in the output of 'gm identify -verbose' and
may be set using the -define syntax (e.g. '-define
dpx:mp.frame.position=2000') on the command line in order to add a value,
or override an existing value. The attributes in the list below may be
viewed or updated. The names are similar to the attribute descriptions
from the DPX standard.</p>
<pre class="literal-block">
dpx:file.copyright
dpx:file.creation.datetime
dpx:file.creator
dpx:file.encryption.key
dpx:file.filename
dpx:file.project.name
dpx:file.version
dpx:image.orientation
dpx:mp.count
dpx:mp.film.manufacturer.id
dpx:mp.film.type
dpx:mp.format
dpx:mp.frame.id
dpx:mp.frame.position
dpx:mp.frame.rate
dpx:mp.held.count
dpx:mp.perfs.offset
dpx:mp.prefix
dpx:mp.sequence.length
dpx:mp.shutter.angle
dpx:mp.slate.info
dpx:source.aspect.ratio.horizontal
dpx:source.aspect.ratio.vertical
dpx:source.border.validity.bottom
dpx:source.border.validity.left
dpx:source.border.validity.right
dpx:source.border.validity.top
dpx:source.creation.datetime
dpx:source.device.name
dpx:source.device.serialnumber
dpx:source.filename
dpx:source.scanned.size.x
dpx:source.scanned.size.y
dpx:source.x-center
dpx:source.x-offset
dpx:source.x-original-size
dpx:source.y-center
dpx:source.y-offset
dpx:source.y-original-size
dpx:tv.black.gain
dpx:tv.black.level
dpx:tv.breakpoint
dpx:tv.field.number
dpx:tv.gama
dpx:tv.horizontal.sampling.rate
dpx:tv.integration.time
dpx:tv.interlace
dpx:tv.sync.time
dpx:tv.temporal.sampling.rate
dpx:tv.time.code
dpx:tv.user.bits
dpx:tv.video.signal
dpx:tv.white.level
dpx:user.data.id
</pre>
<p>Specific header values from a DPX file may be displayed quickly using a command
similar to:</p>
<pre class="literal-block">
gm identify -format '%[DPX:tv.time.code]' foo.dpx
</pre>
<p>Use</p>
<pre class="literal-block">
gm identify -format '%[dpx:*]' foo.dpx
</pre>
<p>to list all DPX header attributes.</p>
<hr class="docutils" />
<p>Copyright © <a class="reference external" href="index.html">GraphicsMagick</a> Group 2002 - 2012</p>
</div>
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</div>
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