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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Adding a rigidity mask</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="The Liquid Rescale library Manual"><link rel="up" href="api-manual.html" title="Chapter 2. LqR library API user manual"><link rel="prev" href="bias.html" title="Adding a bias"><link rel="next" href="tuning.html" title="Tuning"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Adding a rigidity mask</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bias.html">Prev</a> </td><th width="60%" align="center">Chapter 2. LqR library API user manual</th><td width="20%" align="right"> <a accesskey="n" href="tuning.html">Next</a></td></tr></table><hr></div><div class="sect1" title="Adding a rigidity mask"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="rigmask"></a>Adding a rigidity mask</h2></div></div></div><div class="toc"><dl><dt><span class="sect2"><a href="rigmask.html#rigmask-foreword">Foreword</a></span></dt><dt><span class="sect2"><a href="rigmask.html#rigmask-xy">Adding an individual rigidity coefficient to a pixel</a></span></dt><dt><span class="sect2"><a href="rigmask.html#rigmask-float">Using an array of floating-point values</a></span></dt><dt><span class="sect2"><a href="rigmask.html#rigmask-rgb">Using another image</a></span></dt><dt><span class="sect2"><a href="rigmask.html#rigmask-areas">Operating on a specific area</a></span></dt></dl></div><div class="sect2" title="Foreword"><div class="titlepage"><div><div><h3 class="title"><a name="rigmask-foreword"></a>Foreword</h3></div></div></div><p>
The rigidity parameter which is set at carver activation time (see section
<a class="link" href="generate-multi-size.html#carver-init" title="Carver activation">Carver activation</a>) normally affects the whole image. It is
possible, however, to specify which areas of the image should be affected by using a rigidity mask.
</p><p>
When a rigidity mask is used, each pixel of the image acquires an individual rigidity coefficient,
which has to be multiplied with the overall rigidity parameter to get the actual pixel's rigidity.
This is useful in some situations to reduce distorsions in specific areas of the image while keeping
the seams optimal in other areas.
</p><p>
The library interface to deal with rigidity masks follows very closely the scheme for bias masks as
described in the <a class="link" href="bias.html" title="Adding a bias">bias section</a>, the main difference being that no
equivalent to the bias factor has to be provided (since it is already given in the
<code class="function">lqr_carver_init</code> function).
</p><div class="important" title="Important" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Important</h3><p>
The rigidity mask has to be added always <span class="emphasis"><em>after</em></span> the <code class="classname">LqrCarver</code>
initialization and <span class="emphasis"><em>before</em></span> resizing takes place. (Note that this is
different from the bias, which instead can also be added to non-initialised carver objects.)
</p></div><div class="important" title="Important" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Important</h3><p>
Whenever a rigidity mask is set, all pixels for which the value is not explicitly defined will
have coefficient 0, i.e. the rigidity setting will will be disabled.
</p></div><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
All of the functions can be called multiple times, but their effect is not summed up, to the
contrary of what happens for the bias functions; instead, new values will substitute old ones
when the affected regions overlap.
</p></div></div><div class="sect2" title="Adding an individual rigidity coefficient to a pixel"><div class="titlepage"><div><div><h3 class="title"><a name="rigmask-xy"></a>Adding an individual rigidity coefficient to a pixel</h3></div></div></div><p>
The function to use in order to set the rigidity mask at a given pixel is:
</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">LqrRetVal <b class="fsfunc">lqr_carver_rigmask_add_xy</b>(</code></td><td>LqrCarver* <var class="pdparam">carver</var>, </td></tr><tr><td> </td><td>gdouble <var class="pdparam">rigidity</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">x</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">y</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
</p></div><div class="sect2" title="Using an array of floating-point values"><div class="titlepage"><div><div><h3 class="title"><a name="rigmask-float"></a>Using an array of floating-point values</h3></div></div></div><p>
It is possible to use a whole array of floating points at once through this function:
</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">LqrRetVal <b class="fsfunc">lqr_carver_rigmask_add</b>(</code></td><td>LqrCarver* <var class="pdparam">carver</var>, </td></tr><tr><td> </td><td>gdouble* <var class="pdparam">buffer</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
</p><p>
Here, <em class="parameter"><code>buffer</code></em> is an array contining the rigidity coefficients values, and it
is assumed to have the same size as the image loaded in <em class="parameter"><code>carver</code></em>.
</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
This function, and all the following, will not swallow the buffer (to the contrary of what
happens e.g. when creating a new <code class="classname">LqrCarver</code> object and allowing the default behaviour),
therefore the buffer must be freed by the user afterwards.
</p></div></div><div class="sect2" title="Using another image"><div class="titlepage"><div><div><h3 class="title"><a name="rigmask-rgb"></a>Using another image</h3></div></div></div><p>
The rigidity mask can also be read from an 8-bit rgb buffer. This buffer has to be in the same
format as the one used in the 8-bit LqrCarver constructor (but may have a different number of
colours per channel). The function is:
</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">LqrRetVal <b class="fsfunc">lqr_carver_rigmask_add_rgb</b>(</code></td><td>LqrCarver* <var class="pdparam">carver</var>, </td></tr><tr><td> </td><td>guchar* <var class="pdparam">buffer</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">channels</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
</p><p>
As in the previous case, <em class="parameter"><code>buffer</code></em> is assumed to hold and image of the same size
as the one in the <em class="parameter"><code>carver</code></em>.
</p><p>
The <em class="parameter"><code>buffer</code></em> contents will be transformed into floating-points by averaging the
colour components and multiplying the result by the alpha channel (transparency) value.
</p><div class="important" title="Important" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Important</h3><p>
The existence of an alpha channel is inferred from the <em class="parameter"><code>channels</code></em> value: if
this is 1 or 3, no alpha channel is assumed, if it is 2 or 4, it is assumed that the last
channel is holds the alpha value. If this is not what you want, you should resort to one of the
previous methods.
</p></div></div><div class="sect2" title="Operating on a specific area"><div class="titlepage"><div><div><h3 class="title"><a name="rigmask-areas"></a>Operating on a specific area</h3></div></div></div><p>
The two previously described functions operate on the whole <code class="classname">LqrCarver</code> image. It is also possible
to access specific image regions in a similar way; for the floating point use:
</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">LqrRetVal <b class="fsfunc">lqr_carver_rigmask_add_area</b>(</code></td><td>LqrCarver* <var class="pdparam">carver</var>, </td></tr><tr><td> </td><td>gdouble* <var class="pdparam">buffer</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">width</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">height</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">x_off</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">y_off</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
while for the rgb image use:
</p><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">LqrRetVal <b class="fsfunc">lqr_carver_rigmask_add_rgb_area</b>(</code></td><td>LqrCarver* <var class="pdparam">carver</var>, </td></tr><tr><td> </td><td>guchar* <var class="pdparam">buffer</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">channels</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">width</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">height</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">x_off</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">y_off</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
</p><p>
In both functions, <em class="parameter"><code>width</code></em> and <em class="parameter"><code>height</code></em> are used to specify the size of the area of interest,
while <em class="parameter"><code>x_off</code></em> and <em class="parameter"><code>y_off</code></em> specify its offset. For the
rest, both functions work in the same way as their global couterpart.
</p><p>
The provided buffers have to be of size <code class="literal"><em class="parameter"><code>width</code></em> * <em class="parameter"><code>height</code></em></code> (or
<code class="literal"><em class="parameter"><code>width</code></em> * <em class="parameter"><code>height</code></em> * <em class="parameter"><code>channels</code></em></code> for the rgb case) but the specified
areas need not to be strictly included inside the <code class="classname">LqrCarver</code> image area : only the parts which
overlap with it will be used. For example, the offsets can also be negative.
</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="bias.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="api-manual.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="tuning.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Adding a bias </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Tuning</td></tr></table></div></body></html>
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