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<!-- name="David Mosberger-Tang" -->
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<!-- subject="Re: umax-backend" -->
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<title>sane-devel: Re: umax-backend</title>
<h1>Re: umax-backend</h1>
<b>David Mosberger-Tang</b> (<a href="mailto:David.Mosberger@acm.org"><i>David.Mosberger@acm.org</i></a>)<br>
<i>Sun, 31 Aug 1997 12:16:42 -0700</i>
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<i>&gt;&gt;&gt;&gt;&gt; On Sun, 31 Aug 1997 10:48:02 +0200 (MET DST), <a href="mailto:Oliver.Rauch@Wolfsburg.DE">Oliver.Rauch@Wolfsburg.DE</a> said:</i><br>
<p>
Oliver&gt; Hello David, hello Tristan, hello others I want so support<br>
Oliver&gt; the 30-bit mode of the UMAX Astra- and the UMAX High-End<br>
Oliver&gt; scanners.<br>
<p>
Sounds good!<br>
<p>
Oliver&gt; That can be devided into two parts, from which only the<br>
Oliver&gt; first is important at the moment:<br>
<p>
Oliver&gt; 1) Gamma correction with 10 bits input and 8 bits output ( =<br>
Oliver&gt; 1024 bytes instead of 256 bytes )<br>
<p>
I don't understand. Gamma is something defined by the backend. If<br>
you want to define a vector of integers with a range larger than<br>
0..255 then you just change your backend accordingly. Everything<br>
will (should) fall out automatically.<br>
<p>
Oliver&gt; 2) a real 10 bits per pixel (greyscale) and 30 bits per<br>
Oliver&gt; pixel (rgb) support by sane =&gt; 2 bytes per pixel (greyscale)<br>
Oliver&gt; and 6 bytes per pixel (rgb) and 10 to 10 bits gamma data<br>
Oliver&gt; support<br>
<p>
Yes, more than 8 bit/channel is certainly desirable and planned. I<br>
think we defined that you'll have to declare it as 16 bits/channel and<br>
scale the 10 bit values accordingly (I may be misremembering though,<br>
so be sure to look at the spec).<br>
<p>
Unfortunately, neither GIMP nor PPM support more than 24 bpp so the<br>
real thing that's missing is frontend support. Incidentally, isn't 30<br>
bpp mode normally used to achieve higher resolution through<br>
interpolation? I imagine such a feature would be more useful for the<br>
average user than 30bpp support---though I'm not claiming that 30bpp<br>
is never useful.<br>
<p>
--david<br>
<p>
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