Reference:Image Map - Revision history

Clipka: /* Using the Alpha Channel */ canonicalize some version numbers

2021-06-09T14:58:37Z

Using the Alpha Channel: canonicalize some version numbers

Jholsenback: consistency

2018-02-04T19:31:52Z

consistency

Jholsenback: version changes

2017-06-30T08:56:53Z

version changes

Jholsenback: version changes

2017-06-26T10:27:38Z

version changes

Jholsenback: changes from talk page

2016-12-23T11:35:43Z

changes from talk page

Clipka: Indexentries fix

2016-12-17T01:19:24Z

Indexentries fix

Jholsenback: indexenrty additions

2016-10-13T10:46:27Z

indexenrty additions

Jholsenback: syntax diagram updates

2016-10-13T08:01:06Z

syntax diagram updates

Clipka: /* The Gamma Option */

2016-10-12T12:29:08Z

The Gamma Option

Clipka: indexentry fix

2016-05-03T23:19:03Z

indexentry fix

@@ Line 120: / Line 120: @@
 <p class="Note"><strong>Note:</strong> In version 3.7 alpha handling for image file output has changed. Effectively, the background <em>now requires</em> a <code>filter</code> or <code>transmit</code> value in order for alpha transparency to work properly.</p>
-<p>Previous versions of POV-Ray always expected <em>straight</em> (aka <em>non-premultiplied</em>) alpha for file input, this has been changed in 3.7 on a per-file-format basis as follows:</p>
+<p>Previous versions of POV-Ray always expected <em>straight</em> (aka <em>non-premultiplied</em>) alpha for file input, this has been changed in v3.7 on a per-file-format basis as follows:</p>
 <ul>
 <li> PNG will use straight alpha as per specification.</li>
 <li> OpenEXR will use <em>associated</em> (ala <em>premultiplied</em>) alpha as per specifications.</li>
-<li> {{New}} as of version 3.8, TIFF will use straight or associated alpha as per the file header (3.7.0 expected associated alpha).</li>
+<li> {{New}} as of version 3.8, TIFF will use straight or associated alpha as per the file header (v3.7.0 expected associated alpha).</li>
 <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>

@@ Line 8: / Line 8: @@
   pigment {
     image_map {
-      [BITMAP_TYPE] &quot;bitmap[.ext]&quot; [gamma GAMMA] [premultiplied BOOL]
+      [BITMAP_TYPE] &quot;filename&quot; [gamma GAMMA] [premultiplied BOOL]
       [IMAGE_MAP_MODS...]
+      }

← Older revision		Revision as of 08:56, 30 June 2017
Line 143:		Line 143:
	<p class="Note"><strong>Note:</strong> See also <code>[[Reference:Background\|background]]</code> and <code>[[Reference:Sky Sphere\|sky_sphere]]</code> for additional information.</p>		<p class="Note"><strong>Note:</strong> See also <code>[[Reference:Background\|background]]</code> and <code>[[Reference:Sky Sphere\|sky_sphere]]</code> for additional information.</p>

−	<p>{{New}} as of version 3.8, using <code>filter all</code> and <code>transmit all</code> on an image file with an alpha channel is now supported properly (requires <code>#version 3.71</code> or higher).</p>	+	<p>{{New}} as of version 3.8, using <code>filter all</code> and <code>transmit all</code> on an image file with an alpha channel is now supported properly (requires <code>#version 3.8</code> or higher).</p>

@@ Line 81: / Line 81: @@
+   }
 </pre>
-<p>Alternatively to a numerical value, <code>srgb</code> may be specified to denote that the file is encoded or pre-corrected using the <em>sRGB transfer function</em> instead of a power-law gamma function. {{New}} in version 3.7.1, other valid special values are <code>bt709</code> and <code>bt2020</code>, denoting that the file is encoded or pre-corrected using the ITU-R BT.709 or BT.2020 transfer function, respectively.</p>
+<p>Alternatively to a numerical value, <code>srgb</code> may be specified to denote that the file is encoded or pre-corrected using the <em>sRGB transfer function</em> instead of a power-law gamma function. {{New}} in version 3.8, other valid special values are <code>bt709</code> and <code>bt2020</code>, denoting that the file is encoded or pre-corrected using the ITU-R BT.709 or BT.2020 transfer function, respectively.</p>
 <p>
 See section [[Documentation:Tutorial Section 3.3#Gamma Handling|Gamma Handling]] for more information on gamma.</p>
@@ Line 124: / Line 124: @@
 <li> PNG will use straight alpha as per specification.</li>
 <li> OpenEXR will use <em>associated</em> (ala <em>premultiplied</em>) alpha as per specifications.</li>
-<li> {{New}} as of version 3.7.1, TIFF will use straight or associated alpha as per the file header (3.7.0 expected associated alpha).</li>
+<li> {{New}} as of version 3.8, TIFF will use straight or associated alpha as per the file header (3.7.0 expected associated alpha).</li>
 <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>
@@ Line 143: / Line 143: @@
 <p class="Note"><strong>Note:</strong> See also <code>[[Reference:Background|background]]</code> and <code>[[Reference:Sky Sphere|sky_sphere]]</code> for additional information.</p>
-<p>{{New}} as of version 3.7.1, using <code>filter all</code> and <code>transmit all</code> on an image file with an alpha channel is now supported properly (requires <code>#version 3.71</code> or higher).</p>
+<p>{{New}} as of version 3.8, using <code>filter all</code> and <code>transmit all</code> on an image file with an alpha channel is now supported properly (requires <code>#version 3.71</code> or higher).</p>

@@ Line 115: / Line 115: @@
 ==Using the Alpha Channel==
 <p>Another way to specify non-filtered transmit transparency in an image map is by using the<em> alpha channel</em>. POV-Ray will automatically use the alpha channel for transmittance when one is stored in the image. PNG file format allows you to store a
-different transparency for each color index in the PNG file, if desired. If your paint programs support this feature of PNG you can do the transparency editing within your paint program rather than specifying transmit values for each color in the POV file. Since PNG and TGA image formats can also store full alpha channel (transparency) information you can generate image maps that have transparency which is not dependent on the color of a pixel but rather its location in the image.</p>
+different transparency for each color index in the PNG file, if desired. If your paint programs support this feature of PNG you can do the transparency editing within your paint program rather than specifying transmit values for each color in the POV file. Since some image formats can also store full alpha channel (transparency) information you can generate image maps that have transparency which is not dependent on the color of a pixel but rather its location in the image.</p>
 <p>Although POV uses <code>transmit 0.0</code> to specify no transparency and <code> 1.0</code> to specify full transparency, the alpha data ranges from 0 to 255 in the opposite direction. Alpha data 0 means the same as <code>transmit 1.0</code> and alpha data 255 produces <code>transmit 0.0</code>.</p>
 <p class="Note"><strong>Note:</strong> In version 3.7 alpha handling for image file output has changed. Effectively, the background <em>now requires</em> a <code>filter</code> or <code>transmit</code> value in order for alpha transparency to work properly.</p>
-<p>Previous versions of POV-Ray always expected straight alpha for file input, this has been changed on a per-file-format basis as follows:</p>
+<p>Previous versions of POV-Ray always expected <em>straight</em> (aka <em>non-premultiplied</em>) alpha for file input, this has been changed in 3.7 on a per-file-format basis as follows:</p>
 <ul>
 <li> PNG will use straight alpha as per specification.</li>
-<li> OpenEXR and TIFF will use associated alpha as per specifications.</li>
+<li> OpenEXR will use <em>associated</em> (ala <em>premultiplied</em>) alpha as per specifications.</li>
 <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>
@@ Line 142: / Line 143: @@
 <p class="Note"><strong>Note:</strong> See also <code>[[Reference:Background|background]]</code> and <code>[[Reference:Sky Sphere|sky_sphere]]</code> for additional information.</p>
-<p>Activating alpha output via <code>Output_Alpha=on</code> or <code>+UA</code>, when used with unsupported file formats generates a warning.</p>
+<p>{{New}} as of version 3.7.1, using <code>filter all</code> and <code>transmit all</code> on an image file with an alpha channel is now supported properly (requires <code>#version 3.71</code> or higher).</p>

@@ Line 70: / Line 70: @@
 <code>once</code> and <code> interpolate</code> described in Bitmap Modifiers</p>
 {{#indexentry:bt709, keyword}}
 {{#indexentry:bt2020, keyword}}
-==The Gamma Option==
+{{#indexentry:srgb, keyword}}
 <p>The default gamma handling rules for any image input file can be overridden by specifying <code>gamma</code> GAMMA immediately after the file name. For example:</p>
 <pre>
@@ Line 84: / Line 85: @@
 See section [[Documentation:Tutorial Section 3.3#Gamma Handling|Gamma Handling]] for more information on gamma.</p>
 {{#indexentry:filter, bitmap modfier}}
 {{#indexentry:transmit, bitmap modifier}}
 {{#indexentry:all}}
 <p>To make all or part of an image map transparent you can specify <code>filter</code> and/or <code>transmit</code> values for the color palette/registers of PNG, GIF or IFF pictures (at least for the modes that use palettes). You can do this by adding the keyword <code>filter</code> or <code>transmit</code> following the filename. The keyword is followed by two numbers. The first number is the palette number value and the second is the amount of transparency. The values should be separated by a comma. For
 example:</p>

@@ Line 5: / Line 5: @@
 <p>The syntax for an <code>image_map</code> is:</p>
 <pre>
- IMAGE_MAP:
+IMAGE_MAP:
   pigment {
     image_map {
-      FUNCTION_IMAGE
+      [BITMAP_TYPE] &quot;bitmap[.ext]&quot; [gamma GAMMA] [premultiplied BOOL]
+      }
-  [PIGMENT_MODFIERS...]
+ [PIGMENT_MODFIERS...]
-−
+ }
-  BITMAP_TYPE:
+IMAGE_MAP:
-   exr | gif | hdr | iff | jpeg | pgm | png | ppm | sys | tga | tiff
+ pigment {
- IMAGE_MAP_MODS:
+   image_map {
-   map_type Type | once | interpolate Type |
+    FUNCTION_IMAGE
-   filter Palette, Amount | filter all Amount |
-   transmit Palette, Amount | transmit all Amount
+  [PIGMENT_MODFIERS...]
- FUNCTION_IMAGE:
-   function I_WIDTH, I_HEIGHT { FUNCTION_IMAGE_BODY }
+BITMAP_TYPE:
- FUNCTION_IMAGE_BODY:
+  exr | gif | hdr | iff | jpeg | pgm | png | ppm | sys | tga | tiff
-   PIGMENT | FN_FLOAT | pattern { PATTERN [PATTERN_MODIFIERS] }
+GAMMA:
 </pre>

@@ Line 32: / Line 32: @@
 </pre>
-{{#indexentry:gif|tga|iff|ppm|pgm|png|jpeg|tiff|sys,image_map}}
+{{#indexentry:gif, image_map}}
 {{#indexentry:image_map, file types}}
 <p>After the optional <em>BITMAP_TYPE</em> keyword is a string expression containing the name of a bitmapped image file of the specified type. If the <em>BITMAP_TYPE</em> is not given, the same type is expected as the type set for output.</p>