<sect2 id="sect-gui-rendopt1">
    
 
 <title>The render options box : quality tab</title>
  
     <figure id="fig-interface-rendopt1">
        <title>The quality tab.</title>
        <screenshot>
          <mediaobject>
            <imageobject>
              <imagedata fileref="figures/interface_rendopt1.png" format="PNG" />
            </imageobject>
            <textobject>
              <phrase></phrase>
            </textobject>
           </mediaobject>
        </screenshot>
      </figure>


<para>
The quality tab contains options relative to the render quality.

<para><guilabel>Quality</guilabel></para>
<para>
Povray can render the scene with several quality levels. You may use this feature to speed up render
during the modelling phase. The levels currently available with Povray 3.6 are :
</para>

<para>
  <itemizedlist>

  <listitem>
      <para>
	<guilabel>0, 1</guilabel>
      </para>
      <para>
	Povray only uses 'Quick colors' as materials. Those quick colors are set in material editor. Light sources
	are not used, only ambient lightning is calculated.
      </para>
    </listitem>


  <listitem>
      <para>
	<guilabel>2, 3</guilabel>
      </para>
      <para>
      Povray still uses quick colors but also diffuse and ambient parameters.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>4 </guilabel>
      </para>
      <para>
      Povray calculates shadows, for each light source but only as simple point lights.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>5</guilabel>
      </para>
      <para>
      Povray calculates shadows, with every light types and light sources features.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>6, 7</guilabel>
      </para>
      <para>
      Povray doesn't use Quick color anymore. Calculate procedural materials instead.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>8</guilabel>
      </para>
      <para>
      Povray calculates reflection, refraction, transmission.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>9, 10, 11</guilabel>
      </para>
      <para>
      Povray computes radiosity ( if set ) and photons.
      </para>
    </listitem>
  </itemizedlist>
</para>



<para><guilabel>Bits per color</guilabel></para>
<para>
Standards image uses 8 bits per color channel. The PNG format can handle up to 16 bits per color. It can be usefull
for grey level images or for high quality video.
</para>

<para><guilabel>Use alpha</guilabel></para>
<para>
For tga and png you can also ask Povray to use an alpha channel, i.e. a channel for transparency. Don't forget to
set a transparent background.
</para>


<para><guilabel>Antialiasing</guilabel></para>
<para>
The antialiasing is a calculation process that smoothes images. It is often necessary to smooth images a little
but use it carefully as it can be really time consuming. Antialiasing options are :
</para>

<para>
  <itemizedlist>

  <listitem>
      <para>
	<guilabel>Antialiasing method</guilabel>
      </para>
      <para>
	Defines the antialiasing method used by Povray. Actually you can choose Adaptive or Recursive method. The Adaptive method is the default one. Recursive method is more accurate but more time consuming.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>Threshold</guilabel>
      </para>
      <para>
	For the adaptive method, the threshold defines the minimum difference between two consecutive pixels that
	cause a new ray calculation ( pixel super sampling ). To have a smoother image set lower values. You should
	avoid values lower than 0.2.
      </para>
    </listitem>

  <listitem>
      <para>
	<guilabel>Depth</guilabel>
      </para>
      <para>
 	With adaptive method, the depth value defines the number of samples used for pixel super sampling.
      </para>
    </listitem>


  <listitem>
      <para>
	<guilabel>Jitter and Jitter amount</guilabel>
      </para>
      <para>
	Jitter is an optionnal process that introduce noise into samples, in order to average results. You can set
the level of jittering with the jitter amount parameter. This shall not be used with animations because noise would
not be the same with each frame and you would see some artifacts.
      </para>
    </listitem>

  </itemizedlist>
</para>



</para>
</sect2>



  <!-- end of button bar docs -->
 
