Reference:File Output Options - Revision history

Clipka: /* Output File Buffer */ canonicalized a version number

2021-06-09T14:11:32Z

Output File Buffer: canonicalized a version number

Jholsenback: technical correction and grammar

2018-10-28T21:52:37Z

technical correction and grammar

Clipka: /* Output File Dithering */

2018-10-28T10:49:21Z

Output File Dithering

Jholsenback: moves and clarity

2018-10-27T17:14:45Z

moves and clarity

Jholsenback: clarity

2018-10-27T17:02:49Z

clarity

Jholsenback: consistency

2018-10-27T16:44:17Z

consistency

Jholsenback: addition

2018-10-27T16:36:49Z

addition

Jholsenback: version 3.8 additions

2018-10-27T16:05:15Z

version 3.8 additions

Jholsenback: continued v3.8

2018-10-27T12:36:37Z

continued v3.8

Jholsenback: output file type related changes and cleanup

2018-10-27T11:45:21Z

output file type related changes and cleanup

Show changes

@@ Line 258: / Line 258: @@
 {{#indexentry:-b}}
 {{#indexentry:Buffer_Size}}
-<p>The output-file buffer options <code>Buffer_Output</code> and <code>Buffer_Size</code> are removed per POV-Ray 3.6</p>
+<p>The output-file buffer options <code>Buffer_Output</code> and <code>Buffer_Size</code> are removed per POV-Ray v3.6</p>
 <p class="Note"><strong>Note:</strong> The options are still accepted, but ignored, in order to be backward compatible with old INI files.</p>

@@ Line 55: / Line 55: @@
 <tr>
-<td><code>+F</code>xn<em>g</em>{{#indexentry:+g}}</td>
+<td><code>+F</code>x<code>g</code>n{{#indexentry:+g}}</td>
-<td>Sets file output on; sets format x, depth n, sets grayscale if applicable</td>
+<td>Sets file output on; sets format x, sets grayscale if applicable, depth n</td>
 </tr>
 <tr>
-<td><code>-F</code>xn<em>g</em>{{#indexentry:-g}}</td>
+<td><code>-F</code>x<code>g</code>n{{#indexentry:-g}}</td>
-<td>Sets file output off; but in future use format x, depth n, sets grayscale if applicable</td>
+<td>Sets file output off; but in future use format x, sets grayscale if applicable, depth n</td>
 </tr>
@@ Line 166: / Line 166: @@
 <p>Currently PNG, and PPM are the only file formats that support grayscale output.</p>
-<p>Finally... when choosing output file options it may be helpful to consider the following:</p>
+<p>Last but not least, when choosing output file options it may be helpful to consider the following:</p>
 <p>PNG is an image format designed not only to replace GIF, but to improve on its shortcomings. PNG offers the highest compression available without loss for high quality applications, such as ray-tracing. In addition to support for variable bit-depths, alpha channel, and grayscale formats, PNG files also store the <code>File_Gamma</code> value so the image displays properly on all systems.</p>

@@ Line 298: / Line 298: @@
 </ul>
-<p>As always file output dithering is off by default, however a {{Change}} in version 3.8 now set's the default dithering method <em>from</em> <code>FS</code> <em>to</em> <code>BN</code> if only <code>+TH</code> is specified.</p>
+<p>As always file output dithering is off by default, however a {{Change}} in version 3.8 now sets the default dithering method <em>from</em> <code>FS</code> <em>to</em> <code>BN</code> if only <code>+TH</code> is specified.</p>
 <p>In version 3.7 the display preview window used Bayer 4x4 dithering. A {{Change}} in version 3.8 has switched that to the recently added blue noise pattern.</p>

@@ Line 155: / Line 155: @@
 <p>Previously, the grayscale PPM (technically PGM) output file format always used linear output. A {{Change}} in v3.8 will match that of the regular non-grayscale PPM format. That is <code>File_Gamma</code> will be honored if specified, otherwise the ITU-R BT.709 gamma transfer function will be applied.</p>
 <p>See also: [[Reference:Height Field|Height Field]] for a description of how POV-Ray heightfields are stored for each file type.</p>
-<p>In <em>previous</em> versions specifying a bit-depth for grayscale file output was simply ignored and the bit-depth was forced to 16 bits per channel. A {{Change}} in version 3.8 now allows for a bit-depth setting.</p>
+<p>Previously, specifying a bit-depth for grayscale file output was simply ignored and the bit-depth was forced to 16 bits per channel. A {{Change}} in version 3.8 now allows for a bit-depth setting.</p>
 <p>It should also be noted that with <em>previous</em> versions setting the <code>Grayscale_Output=true</code> INI option would <em>not</em> cause the preview display, if used, to be grayscale. A {{Change}} in version 3.8 <em>now</em> shows a grayscale image on the preview display as well.</p>
 <p>Currently PNG, and PPM are the only file formats that support grayscale output.</p>
 <p>Finally... when choosing output file options it may be helpful to consider the following:</p>
@@ Line 182: / Line 180: @@
 <p>Specifying a smaller color depth like 5 bits/color (32768 colors) may be enough for people with 8- or 16-bit (256 or 65536 color) displays, and will improve compression of the PNG file. Higher bit depths like 10 or 12 may be useful for video or publishing applications, and 16 bits/color is good for grayscale height field output (See section [[Reference:Height Field|:Height Field|Height Field]] for details on height fields).</p>
-<p>Targa format also allows 8 bits of alpha transparency data to be output, while PNG format allows 5 to 16 bits of alpha transparency data, depending on the color bit depth as specified above. You may turn this option on with <code> Output_Alpha=on</code> or <code>+UA</code>. The default is off or <code> -UA</code>.</p>
+<p>Targa format also allows 8 bits of alpha transparency data to be output, while PNG format allows 5 to 16 bits of alpha transparency data, depending on the color bit depth as specified above. You may turn this option on with <code> Output_Alpha=on</code> or <code>+UA</code>. The default is off or <code> -UA</code>. {{New}} as of version 3.8, instead of <code>Output_File_Type=C</code> you can also use <code>Output_File_Type=T Compression=1</code> to choose RLE-encoded Targa format.</p>
 <p>The alpha channel stores a transparency value for each pixel, just like there is also stored a value for red green and blue light for each pixel. In POV-Ray, when the alpha channel is turned on, all areas of the image where the background is partly or fully visible will be partly or fully transparent. Refractions of the background will also be transparent, but not reflections. Also anti-aliasing is taken into account.</p>

@@ Line 168: / Line 168: @@
 <p>In previous versions PPM output always created the compact <em>raw</em> (binary) format. A {{Change}} in version 3.8 now allows the use of <em>INI</em> setting <code>Compression=0</code> to select the <em>plain</em> (ASCII) format instead. The system specific format depends on the platform used and is covered in the appropriate system specific documentation.</p>
-<p>PNG is an image format designed not only to replace GIF, but to improve on its shortcomings. PNG offers the highest compression available without loss for high quality applications, such as ray-tracing.</p>
+<p>Finally... when choosing output file options it may be helpful to consider the following:</p>
 <p>JPEG is particularly good at achieving high compression rates with photographic or photorealistic images, making it one of the most frequently used formats on the Internet. However, it is not loss-free. Images generated with this option will always contain compression artifacts (image defects). If you need to keep a high-quality image you should render using one of the loss-free formats.</p>
@@ Line 176: / Line 178: @@
 <p>The JPEG compression quality can be controlled using the <code>Compression</code> ini file option which, if set, needs to be an integer between 0 and 100. If values of 0 or 1 are specified then the default compression quality setting of 85% is used. Otherwise the value specified (2-100) is used as the compression quality setting. A value of 2 produces the smallest file (maximum compression), but looks terrible. A value of 100 produces the largest file (least compression) but can still contain some compression artifacts. Values lower than 0 are clipped to 0. Values greater than 100 are clipped to 100.</p>
-<p>Most of these formats output 24 bits per pixel with 8 bits for each of red, green and blue data. PNG and PPM allow you to optionally specify the output bit depth from 5 to 16 bits for each of the red, green, and blue colors, giving from 15 to 48 bits of color information per pixel. The default output depth for all formats is 8 bits/color (16 million possible colors), but this may be changed for PNG and PPM format files by setting <code>Bits_Per_Color=</code><em>n</em> or by specifying <code>+FN</code><em>n</em> or <code>+FP</code><em>n</em>, where n is the desired bit depth.</p>
+<p>Most of these formats output 24 bits per pixel with 8 bits for each of red, green and blue data. PNG and PPM allow you to optionally specify the output bit depth from 1 to 16 bits for each of the red, green, and blue colors, giving from 15 to 48 bits of color information per pixel. The default output depth for all formats is 8 bits/color (16 million possible colors), but this may be changed for PNG and PPM format files by setting <code>Bits_Per_Color=</code><em>n</em> or by specifying <code>+FN</code><em>n</em> or <code>+FP</code><em>n</em>, where n is the desired bit depth.</p>
 <p>Specifying a smaller color depth like 5 bits/color (32768 colors) may be enough for people with 8- or 16-bit (256 or 65536 color) displays, and will improve compression of the PNG file. Higher bit depths like 10 or 12 may be useful for video or publishing applications, and 16 bits/color is good for grayscale height field output (See section [[Reference:Height Field|:Height Field|Height Field]] for details on height fields).</p>
@@ Line 197: / Line 199: @@
   <li> TGA and BMP 32-bit RGBA will use straight alpha, retaining file input compatibility for now, until a final decision has been made on these formats.</li>
 </ul>
 <p>The [http://radsite.lbl.gov/radiance/HOME.html Radiance] Synthetic Imaging System or <em>.hdr</em> image format was originally developed to aid lighting designers and architects by predicting the light levels and appearance of a space prior to construction. The [http://www.openexr.com/index.html OpenEXR] or <em>.exr</em> image file format was developed by Industrial Light & Magic&trade; for use in computer imaging applications.</p>

@@ Line 150: / Line 150: @@
 </table>
-<p>Grayscale output can be used to generate heightfields for use in other POV-Ray scenes, by using <code>Grayscale_Output=true</code> as an INI option, or <code>+Fxg</code> for output type <em>x</em> as a command-line option. For example, <code>+Fng</code> for PNG and <code>+Fpg</code> for PPM (effectively PGM) grayscale output. By default this option is off.</p>
+<p>Grayscale output can be used to generate heightfields for use in other POV-Ray scenes, by using <code>Grayscale_Output=true</code> as an INI option, or <code>+Fxg</code> for output type <em>x</em> as a command-line option. For example, <code>+Fng</code> for PNG and <code>+Fpg</code> for PPM (technically PGM) grayscale output. By default this option is off.</p>
 <p>With <code>Grayscale_Output=true</code>, the output file will be in the form of a grayscale image that can be used to generate heightfields, as the height at any point is dependent on the brightness of the pixel. The brightness of a pixel is calculated in the same way that color images are converted to grayscale images:<em><code> height = 0.3 * red + 0.59 * green + 0.11 * blue</code></em>.</p>

← Older revision		Revision as of 16:36, 27 October 2018
Line 303:		Line 303:

	<p>In version 3.7 the display preview window used Bayer 4x4 dithering. A {{Change}} in version 3.8 has switched that to the recently added blue noise pattern.</p>		<p>In version 3.7 the display preview window used Bayer 4x4 dithering. A {{Change}} in version 3.8 has switched that to the recently added blue noise pattern.</p>
		+
		+	<p>{{New}} in version 3.8 dithering is now fully supported for Radiance HDR output files.</p>

	<p>{{New}} in version 3.8 file output dithering is now fully gamma-aware. The overall apparent brightness of the resulting image is faithfully reproduced.</p>		<p>{{New}} in version 3.8 file output dithering is now fully gamma-aware. The overall apparent brightness of the resulting image is faithfully reproduced.</p>

@@ Line 280: / Line 280: @@
 </table>
 <ul>
-<li><code>B2</code>..<code>B4</code>: Bayer pattern dithering using 2x2, 3x3 or 4x4 patterns, respectively</li>
+  <li><code>B2</code>..<code>B4</code>: Bayer pattern dithering using 2x2, 3x3 or 4x4 patterns, respectively</li>
-<li><code>D1</code>: Simple 1-dimensional error diffusion dithering</li>
+  <li><code>BN</code>: Blue noise pattern dithering using a 64x64 pattern. {{New}} in version 3.8</li>
-<li><code>D2</code>: Simple 2-dimensional error diffusion dithering (needs extra memory for 2 pixel rows)</li>
+  <li><code>BNX</code>: same as BN but using the pattern's inverse for the R and B channels. {{New}} in version 3.8</li>
 </ul>
-<p>The default is <code>-THfs</code> i.e: dithering is off, with Floyd-Steinberg being the default if only  <code>+TH</code> is specified.</p>
+<p>Error diffusion dithering algorithms:</p>
 <p>Dithering works for all file formats except JPEG (where dithering would be counter-productive) and OpenEXR (which provides sufficient precision to make dithering obsolete). These file formats simply ignore the setting.</p>