| Re: grey scale [message #12481] |
Fri, 14 August 1998 00:00 |
wmc
Messages: 117
Registered: February 1995
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Senior Member |
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Harry Reisig (hreisig@engin.umich.edu) writes:
> We tried loadct, 0 - but it is not publishing quality. Is there another
> grey scale that give sharper images? We are trying to print color images,
> which gives a lot of information that is lost in ct 0.
I recently had what may be the same problem - (though its not an IDL colour
table, I'm pretty sure, because I was printing in BW): colour indexes 0-255 are
not all distinguishable on our laser printer. 252-254 are the same; 250-251 ditto,
etc etc mostly in groups of 2. At the lower end, 0-15 and 16-31 are
indistinguishable. They are also dithered, which is OK for the large boxes
of my test-colours print, but if you tried to print a high-res image the dithering
would probably get in the way. It looks to me like our laser printers fault -
perhaps you have the same problem?
- William, just guessing again.
---
William M Connolley | wmc@bas.ac.uk | http://www.nbs.ac.uk/public/icd/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
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| Re: grey scale [message #12492 is a reply to message #12481] |
Thu, 13 August 1998 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Harry Reisig (hreisig@engin.umich.edu) writes:
> We tried loadct, 0 - but it is not publishing quality. Is there another
> grey scale that give sharper images? We are trying to print color images,
> which gives a lot of information that is lost in ct 0.
How, exactly, can this happen?
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438, Toll Free Book Orders: 1-888-461-0155
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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| Re: grey scale [message #12495 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
David Foster
Messages: 341
Registered: January 1996
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Senior Member |
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Martin Schultz wrote:
>
> Harry Reisig wrote:
>>
>> Howdy -
>> Does anyone know if there is a grey-scale color table on IDL 5.0.2 (for
>> PowerMac)? I need to publish some tvscl images (currently being viewed with
>> color table 4) in grey-scale.
>> I imagine that there is one posted somewhere, but I don't know where.
>> Thanks
>> Harry
You might find my GRAYSCALE.PRO routine useful; it creates a widget
that allows you to adjust the grayscale interactively. This is part
of a larger set of routines available at:
ftp://bial8.ucsd.edu pub/software/idl/share/idl_share.tar.gz
There is a README file describing each routine available. Each
routine has a .doc documentation file, and you can view all of these
(once files have been extracted) using my LHELP.PRO program.
Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
David S. Foster Univ. of California, San Diego
Programmer/Analyst Brain Image Analysis Laboratory
foster@bial1.ucsd.edu Department of Psychiatry
(619) 622-5892 8950 Via La Jolla Drive, Suite 2240
La Jolla, CA 92037
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
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| Re: grey scale [message #12499 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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Harry Reisig wrote:
>
> We tried loadct, 0 - but it is not publishing quality. Is there another
> grey scale that give sharper images? We are trying to print color images,
> which gives a lot of information that is lost in ct 0.
> Thanks
> Harry
[...]
Maybe you don't want a greyscale colortable after all !! If you want to
print color images in black and white, you may get a more "natural"
image using the colortable that comes with the image (assuming you read
the image with read_tiff, read_gif or the likes). Then you simply have
to produce a *color* postscript file and send it to a b/w printer ;-)
Other than that, you can follow the approach I outlined in my earlier
message and define the colortable yourself. You can create virtually
anything, then convert it to a 0..255 byte array with bytscl and load it
into the color table with tvlct. If you don't like linear grey scale you
can use logarithmic, or you can play around with some arctan function,
etc...
Martin.
------------------------------------------------------------ -------
Dr. Martin Schultz
Department for Earth&Planetary Sciences, Harvard University
109 Pierce Hall, 29 Oxford St., Cambridge, MA-02138, USA
phone: (617)-496-8318
fax : (617)-495-4551
e-mail: mgs@io.harvard.edu
Internet-homepage: http://www-as.harvard.edu/people/staff/mgs/
------------------------------------------------------------ -------
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| Re: grey scale [message #12502 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
Richard G. French
Messages: 65
Registered: June 1997
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Member |
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Harry Reisig wrote:
>
> We tried loadct, 0 - but it is not publishing quality. Is there another
> grey scale that give sharper images? We are trying to print color images,
> which gives a lot of information that is lost in ct 0.
> Thanks
> HarryA
Are you sure you are using 8 bits per pixel?
try doing
device,BIT=8
and see if that helps the quality of the PostScript output.
Dick French
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| Re: grey scale [message #12504 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
Harry Reisig
Messages: 6
Registered: July 1998
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Junior Member |
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We tried loadct, 0 - but it is not publishing quality. Is there another
grey scale that give sharper images? We are trying to print color images,
which gives a lot of information that is lost in ct 0.
Thanks
Harry
----------
In article <Saeid.Zoonematkermani-1308981200140001@ozone.ess.sunysb.edu>,
Saeid.Zoonematkermani@sunysb.edu (Saeid Zoonematkermani) wrote:
> In article <6qstk5$38d@srvr1.engin.umich.edu>, "Harry Reisig"
> <hreisig@engin.umich.edu> wrote:
>
>> Howdy -
>> Does anyone know if there is a grey-scale color table on IDL 5.0.2 (for
>> PowerMac)? I need to publish some tvscl images (currently being viewed with
>> color table 4) in grey-scale.
>> I imagine that there is one posted somewhere, but I don't know where.
>> Thanks
>> Harry
>
> Hi,
>
> I just tried sending you a reply via e-mail and it bounced back. There
> must be some thing wrong in your e-mail address.
>
> Any way, the answer is that the default color table is grey scale so you
> should not need to do any thing if you have just launched IDL. If you have
> already specified another color table, try:
>
> IDL> loadct, 0
>
> Cheers,
>
> - Saeid
>
> --
> Saeid Zoonematkermani
> Dept. of Physics & Astronomy
> State University of New York
> Stony Brook, NY 11794-3800
>
> EMail: Saeid.Zoonematkermani@sunysb.edu
> Voice: (+1) (516) 632-8237 Fax: (+1) (516) 632-8742
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| Re: grey scale [message #12506 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
Saeid.Zoonematkermani
Messages: 6
Registered: December 1997
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Junior Member |
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In article <6qstk5$38d@srvr1.engin.umich.edu>, "Harry Reisig"
<hreisig@engin.umich.edu> wrote:
> Howdy -
> Does anyone know if there is a grey-scale color table on IDL 5.0.2 (for
> PowerMac)? I need to publish some tvscl images (currently being viewed with
> color table 4) in grey-scale.
> I imagine that there is one posted somewhere, but I don't know where.
> Thanks
> Harry
Hi,
I just tried sending you a reply via e-mail and it bounced back. There
must be some thing wrong in your e-mail address.
Any way, the answer is that the default color table is grey scale so you
should not need to do any thing if you have just launched IDL. If you have
already specified another color table, try:
IDL> loadct, 0
Cheers,
- Saeid
--
Saeid Zoonematkermani
Dept. of Physics & Astronomy
State University of New York
Stony Brook, NY 11794-3800
EMail: Saeid.Zoonematkermani@sunysb.edu
Voice: (+1) (516) 632-8237 Fax: (+1) (516) 632-8742
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| Re: grey scale [message #12510 is a reply to message #12492] |
Thu, 13 August 1998 00:00 |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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Harry Reisig wrote:
>
> Howdy -
> Does anyone know if there is a grey-scale color table on IDL 5.0.2 (for
> PowerMac)? I need to publish some tvscl images (currently being viewed with
> color table 4) in grey-scale.
> I imagine that there is one posted somewhere, but I don't know where.
> Thanks
> Harry
should be colortable 0 (at least this is the number for Unix).
If loadct,0 does not work, try the following
cvec = bytscl(indgen(!D.N_COLORS),top=255) ; create grey scale
tvlct,cvec,cvec,cvec ; store the color table
If you apply REVERSE() to bytscl, you will get colors from white to
black.
Hope this helps,
Martin.
--
------------------------------------------------------------ -------
Dr. Martin Schultz
Department for Earth&Planetary Sciences, Harvard University
109 Pierce Hall, 29 Oxford St., Cambridge, MA-02138, USA
phone: (617)-496-8318
fax : (617)-495-4551
e-mail: mgs@io.harvard.edu
Internet-homepage: http://www-as.harvard.edu/people/staff/mgs/
------------------------------------------------------------ -------
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