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Diffstat (limited to 'winicontopam.html')
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1 files changed, 20 insertions, 9 deletions
diff --git a/winicontopam.html b/winicontopam.html index 53d3b357..3baa4d33 100644 --- a/winicontopam.html +++ b/winicontopam.html @@ -2,7 +2,7 @@ <html><head><title>Winicontopam User Manual</title></head> <body> <h1>winicontopam</h1> -Updated: 12 April 2013 +Updated: 29 August 2020 <br> <a href="#index">Table Of Contents</a> @@ -28,12 +28,21 @@ its value. <p>This program is part of <a href="index.html">Netpbm</a>. -<p><b>winicontopam</b> reads a Microsoft Windows icon file and -converts it to one or more RGB_ALPHA Netpbm PAM images. +<p><b>winicontopam</b> reads a Microsoft Windows icon file and converts it to +one or more RGB_ALPHA Netpbm PAM images. -<p>The transparency channel is copied from the 8-bit transparency data from -the icon, if present. If no 8-bit transparency data is available, the -transparency channel is constructed from the so-called "AND mask". +<p>There are two kinds of transparency information a a Windows icon can have: +and mask and graded transparency map. The and mask is older and indicates for +each pixel whether it is fully opaque or fully transparent. The graded +transparency map can indicate translucent values too. The graded transparency +map is present in an icon that uses PNG encoding or uses BMP encoding with 32 +bits per pixel. + +<p>The transparency plane in the PAM output of <b>winicontopam</b> comes from + the graded transparency map if it exists and the and mask otherwise. + +<p>An icon may actually have both forms of transparency information. See +<b>-andmasks</b>. <p>The output goes to Standard Output. @@ -70,9 +79,11 @@ image (largest, then most bits per pixel). <dt><b>-andmasks</b> -<dd>If the image to be extracted contains both 8-bit transparency -data and AND mask, produce five-channel Netpbm PAM images with the AND -mask as the fifth plane. +<dd>If the image to be extracted contains both graded transparency data and an +AND mask, produce five-channel Netpbm PAM images with the AND mask as the +fifth plane. An image that formally has graded transparency data, but it +indicates nothing but opaque pixels is considered not to have graded +transparency data, so <b>-andmasks</b> would have no effect on it. <dt><b>-verbose</b> |