Hi Oliver, Hi Umax users,
In order to support more resolutions for Umax Astra 6x0S, I changed one
line from umax-scsi.c, this way :
us->CCD_distance = us->inquiry_CCD_line_distance;
become
us->CCD_distance = us->y_resolution / 37.5 +.5;
This way, you get correct images at 4 different resolutions (75, 150,
225 and 300 dpi).
After this change, all images (except the 4 resolutions above) need to
be ccd-corrected, but with a float ccd value, -1 < ccd < 1
The only way I find to ccd-correct those images is to add part of the
current line value for a given channel with part of the above line value
for the same channel and to use this value.
For example, with a float ccd of .12, I take 88% (100-12) of the current
line + 12% of the above line for blue channel and 76% (100-12*2) of the
current line + 24% (12*2) of the above line for the green channel. If
float ccd is <0, I swap the % values. [This is for Astra 610S, for 600S,
replace green with red].
can't find another way to do this.
Do they *really* do this that way ?
Nicolas.
Attached: ccd.html, a Javascript program to display the line ccd, the
float ccd and the % value for all resolutions from 1 to 300. [This is
for Astra 610S, replace green with red for 600S.] Sorry for those who
can't run Javascript programs.
--------------6F43E614EDEAF6DFFF405F5C
Content-Type: text/html; charset=us-ascii; name="ccd.html"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="ccd.html"
Content-Base: "file:/home/nicolas/ccd.html"
<body>
<table border=1 width="100%">
<tr>
<th>Resolution</th>
<th>ccd</th>
<th>integer ccd</th>
<th>float ccd</th>
<th>n * currentGreen</th>
<th>n * previousGreen</th>
<th>n * currentBlue</th>
<th>n * previousBlue</th>
</tr>
<script language=javascript>
for (r=1;r<=300;r++)
{
ccd=r/37.5
ccdl=Math.floor(ccd+.5)
ccdf=ccd-ccdl
if (ccdf>=0)
{
bp=ccdf
bc=1-bp
gp=ccdf*2
gc=1-gp
}
else
{
bc=-ccdf
bp=1-bc
gc=-ccdf*2
gp=1-gc
}
document.write(
'<tr align=center>',
'<td>',r,'</td>',
'<td>',ccd,'</td>',
'<td>',ccdl,'</td>',
'<td>',ccdf,'</td>',
'<td>',gc,'</td>',
'<td>',gp,'</td>',
'<td>',bc,'</td>',
'<td>',bp,'</td>',
'</tr>'
)
}
</script>
<tr>
<th>Resolution</th>
<th>ccd</th>
<th>integer ccd</th>
<th>float ccd</th>
<th>n * currentGreen</th>
<th>n * previousGreen</th>
<th>n * currentBlue</th>
<th>n * previousBlue</th>
</tr>
</table>
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