Enhancing Satellite Weather Images
Aug 28 2005 SRIV After noticing that some of the NOAA enhance satellite images were being delayed around 1-2 hours, I decided to try to enhance the higher resolution black & white images.
This script will download and display the latest North America image, then enhance the image with colors. Here is what the output looks like: http://server.linuxsys.net/images/latest_eastir_eh.gif compared to NOAA's image http://server.linuxsys.net/images/satimg.jpg .
RS Here's a snapshot of the Katrina Category 5 Hurricane (between Florida and N.O.) on 2005-08-28:
sriv Updated source image from the SSEC image server so I can track hurricane Sandy
# satenhance.tcl 08-28-2005 Steve Redler IV
# sriv 10-27-2012 updated to new url for source image and adjusted the comb filter parameters
package require Tk
package require http
canvas .c -width 1000 -height 900
pack .c
proc comb {x spec} {
foreach {value limit} $spec {if {$x<$limit} break}
set value
}
proc colorize {image} {
# get image sizes
set width [image width $image]
set height [image height $image]
set height [image height $image]
set filterlist {
#646400 170
#a0a000 175
#f0f000 180
#000b64 185
#0064aa 190
#00d7e6 195
#720000 200
#960000 205
#d90000 210
#ff5b62 215
#f97f7c 220
#3cd612 225
#84f780 230
#323232 240
#ffffff 254
}
# compute new colors
for {set y 0} {$y < $height} {incr y} {
#puts "row=$y"
set row {}
for {set x 0} {$x < $width} {incr x} {
# save transparency
lappend trans $x $y [$image transparency get $x $y]
# compute the new color
foreach {r g b} [$image get $x $y] break
if {$r < 170} {
lappend row [format #%02x%02x%02x $r $b $g]
} else {
lappend row [comb $r $filterlist]
}
}
# update the row of the image
$image put \{$row\} -to 0 $y
update
}
# restore transparency
foreach {x y t} $trans { $image transparency set $x $y $t }
}
set imagedata [http::data [http::geturl http://www.ssec.wisc.edu/data/geo/east/latest_east_ir2_conus.gif]]
image create photo satimage -data $imagedata
.c create image 0 0 -image satimage -tag imgtag -anchor nw
update
after 100 [colorize satimage]
update
satimage write latest_eastir_eh.gif -format gif21-november-2006 Harm Olthof: changed proc colorize to use proc argument in the put statement.
2011-03-19 tomas Nifty! Some lines in the program were doubled, I don't know why. I removed them.