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<title>sane-devel: Re: [Announce] WinSANE 0.1.0.0 Release</title>
<h1>Re: [Announce] WinSANE 0.1.0.0 Release</h1>
<b>Brian Macy</b> (<a href="mailto:bmacy@sunshinecomputing.com"><i>bmacy@sunshinecomputing.com</i></a>)<br>
<i>Mon, 10 May 1999 08:44:41 -0700</i>
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<i>&gt; No. "packed" modes are violently unpleasant, and while some scanners might</i><br>
<i>&gt; use them to buy some compression, SANE doesn't support any such a format.</i><br>
<i>&gt;</i><br>
<i>&gt; A series of three 10-bit samples (e.g. an RGB pixel captured by a one-pass</i><br>
<i>&gt; 30-bit parallel port scanner) will arive through SANE as...</i><br>
<i>&gt;</i><br>
<i>&gt; 98765432 10------ 98765432 10------ 98765432 10------</i><br>
<i>&gt; Or, alternatively (ENDIAN dependence kicks in here)</i><br>
<i>&gt; 10------ 98765432 10------ 98765432 10------ 98765432</i><br>
<i>&gt;</i><br>
<i>&gt; The ---- sequences will usually be either zero, or copied from the top</i><br>
bits<br>
<i>&gt; of the 10-bit sample (explanation a few weeks ago on this list). The</i><br>
<i>&gt; backend should tell you how many bits are "really there" in any case.</i><br>
<i>&gt; You can tell which way around the samples are from the ENDIAN stuff set</i><br>
<i>&gt; by the sender. Your job, as a recipient, is to correct anything which is</i><br>
<i>&gt; "the wrong way around" for your application/ platform.</i><br>
<i>&gt;</i><br>
<i>&gt; Note that since the _high_ bits are used, you could assume that you're</i><br>
<i>&gt; always receiving true 16-bit samples. For a simple application (like</i><br>
<i>&gt; photo retouching) this is probably fairly safe.</i><br>
<p>
Hmmm... so are you saying that anything greater than 1bit depth uses byte<br>
aligned data??? Actually the docs (3.2) say "Valid bit depths are 1, 8, or<br>
16 bits per sample. If a device's natural bit depth is something else, it is<br>
up to the driver to scale the sample values appropriately (e.g., a 4 bit<br>
sample could be scaled by a factor of four to represent a sample value of<br>
depth 8)." So if there is a bit depth of 10 the driver better scale it to<br>
16bits and the LSB format must be:<br>
98765432 xxxxxx10 (where the x's must be zero)<br>
or some value scaled to a 16bit value.<br>
<p>
Oh wait.... never mind... the 10bit value is getting left shifted 6bits to<br>
scale it up to the 16bit values.<br>
<p>
BTW thanks much for your help.<br>
<p>
Brian Macy<br>
<p>
<p>
<pre>
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