[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

20031006: McIDAS - IRIX64 - How to have a good visible grayscale ET

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: 20031006: McIDAS - IRIX64 - How to have a good visible grayscale ET
  • Date: Mon, 06 Oct 2003 12:47:34 -0600
>From: "Christian =?ISO-8859-1?Q?Pag=E9?=" <address@hidden>
>Organization: UQAM
>Keywords: 200310061749.h96HnLa3019389

Hi Christian,

>Institution: Universite du Quebec a Montreal / Atmospheric Science Group
>Package Version: 2003
>Operating System: IRIX64
>Hardware Information: SGI

>Inquiry: Hi,
>
>I want to have a good enhancement table (in grayscale) for GOES-12
>visible imagery (in McIDAS 2003). I have seen that at UCAR they seem to
>have already solved this problem, since visible imagery enhancement
>table for winter, summer, sunset, sunrise, etc. are all very good. Is
>there already something in McIDAS that would to that automatically
>(select the proper enhancement table given the overall brightness of
>the image by example) ?

There is nothing in McIDAS that will select a particular enhancement
for you based on values in the image being displayed.  You could create
several enhancements or stretch tables that you would use during
different times of the year, but using them would require that you make
the decision as to when to use a particular one.

Another approach that you could take is to setup a cron job that
examines the distribution of brightness levels in an image and, based
on what is seen, generate either a new enhancement or a new stretch of
a fixed name(s) that is used in the display.  What I have in mind is
using a routine like ASTAT to examine data values and then generate
your own enhancement/stretch.

Another thing you could do is to use IMGFILT to do a histogram
equilization on each image (creating a new image) and then load the
modified image using the standard enhancement.  This is the kind of
approach usually taken by folks who are trying to "pretty up"
displays.

>Thanks again,

No worries.

Cheers,

Tom

>From address@hidden Mon Oct  6 14:24:43 2003

Hi Tom,

Thanks a lot for your reply. I implemented IMGFILT in my script and it  
does indeed a good job! :-)
I will be able to look at nice visible satellite images this winter and  
early in the morning when I come to work... :-)

Christian Pagé
UQAM