WXtoIMG Enhancements

From Drake Panzer

Image enhancements used by APTbot for WXtoIMG. Taken from the manpage.

Enhancements

Name Description
ZA NOAA general purpose meteorological IR enhancement option. Increases contrast by saturating the very low and very high temperature regions where there is typically very little information. This enhancement option is temperature normalized.
MB NOAA cold cloud top enhancement option. Useful for showing where the strongest rainfall is occurring in thunderstorms. This enhancement option is temperature normalized.
MD The NOAA MD enhancement is a modification of the popular, general use MB enhancement scheme. It is intended for warm season use, and provides improved enhancement within the gray "step wedges" that depict "warm top" convection. An additional improvement is better delineation of warm low clouds (30C to 7C). The middle cloud range is somewhat broader than the MB, and enhancement of details is minimized. Otherwise, it is the same as the MB enhancement. This enhancement option is temperature normalized.
BD NOAA hurricane enhancement option. Highlights certain temperatures in the eye and eye wall of the storm system which are known to be related to the intensity of the hurricane. This enhancement option is temperature normalized.
CC NOAA CC enhancement curve. This enhancement option is temperature normalized.
EC NOAA EC enhancement curve. This enhancement option is temperature normalized.
HE The NOAA HE enhancement is used principally by weather offices in the western United States. It provides good enhancement of a wide variety of cloud types, but is somewhat complex, and may be difficult to use at first. It enhances low and middle level clouds common along the Pacific Coast of North America in two separate gray shade ranges. The freezing level is easily determined, an advantage for aviation users concerned with icing. Step wedge regions display very cold infrared cloud top temperatures associated with thunderstorms and frontal systems in 5 degree increments down to -60 C. Two additional "repeat gray" segments define cloud top temperatures colder than -60C. This enhancement option is temperature normalized.
HF The NOAA HF enhancement is the most current of the "H" series of enhancements, and is used principally by weather offices in the western United States. It provides good enhancement of low and middle level clouds common along the Pacific Coast of North America. Step wedge regions display very cold infrared cloud top temperatures associated with thunderstorms and frontal systems in 5 degree increments down to -60 C. Two additional "repeat gray" segments define cloud top temperatures colder than -60C. This enhancement option is temperature normalized.
JF The NOAA JF enhancement is a hybrid enhancement scheme used to highlight both sea surface temperatures, and cold cloud tops associated with thunderstorms and other weather systems. It is somewhat simpler to interpret than the later JJ enhancement. The coldest portion of the enhancement (less than -33C) is nearly identical to the general-use MB enhancement. Maximum enhancement is provided at the warm end (25 to 10C) to depict sea surface temperatures and warm low clouds in tropical and sub-tropical areas. This enhancement option is temperature normalized.
JJ The NOAA JJ enhancement is used to highlight both sea surface temperatures, and cold cloud tops associated with thunderstorms and other weather systems. Maxi- mum enhancement is provided at the warm end (23 to 0C) to depict sea surface temperatures and low clouds. The presence of a freezing level break point is important for aviation users interested in icing conditions. Multiple, steep, ramp enhancement ranges provide considerable detail within cold cloud tops such as thunderstorms, but it is difficult to determine the actual temperatures with any accuracy. This enhancement option is temperature normalized.
LC The NOAA LC curve is used on images from the 3.9 micron shortwave infrared channel (CH2) of GOES. It provides maximum enhancement in the temperature range where fog and low clouds typically occur (36C to -9C). Another enhanced thermal range is from -10C to -29C, the region of precipitation generation in mid- latitude weather systems. Since CH2 is sensitive to "hot spots," a steep, reverse ramp is found at the warm end (68C to 50C) to show any observable fires as white. There is no enhancement at the very cold end (-30 to -67C), due to the instrument noise normally present at these temperatures. This enhancement option is temperature normalized.
TA NOAA TA enhancement curve. This enhancement option is temperature normalized.
WV The modified NOAA WV curve is used for the 6.7 micron water vapor channel (CH3) on GOES. The only temperature range that is enhanced is between -5C and -90C. Temperatures colder than -90C are shown as white, and temperatures warmer than -5C are displayed as black. This enhancement option is temperature normalized. See also WV-old.
WV-OLD The original NOAA WV curve is used for the 6.7 micron water vapor channel (CH3) on GOES. The only temperature range that is enhanced is between -10C and -60C. This is the most important range because it shows middle and upper tropospheric moisture patterns that relate to significant features such as: jet streams, upper troughs, dry slots, and deformation zones. Temperatures colder than -60C are shown as white, and temperatures warmer than -10C are displayed as black. The latter condition is very rare, and occurs mainly in the subtropics. This enhancement option is temperature normalized. See also WV.
NO NOAA color IR contrast enhancement option. Greatly increases contrast in the darker land/sea regions and colors the cold cloud tops. Allows fine detail in land and sea to be seen and provides a very readable indication of cloud top temperatures. This enhancement option is temperature normalized.
MCIR Colors the NOAA sensor 4 IR image using a map to color the sea blue and land green. High clouds appear white, lower clouds gray or land/sea colored, clouds generally appear lighter, but distinguishing between land/sea and low cloud may be difficult. Darker colors indicate warmer regions.
MSA Multispectral analysis. Uses a NOAA channel 2-4 image and determines which regions are most likely to be cloud, land, or sea based on an analysis of the two images. Produces a vivid false-colored image as a result. Note that perfect coloring is difficult to obtain, especially with low illumination angles. Not temperature normalized.
MSA-PRECIP Same as MSA multispectral analysis, but high cold cloud tops are colored the same as the NO enhancement to give an approximate indication of the probability and intensity of precipitation.
HVC Creates a false color image from NOAA APT images based on temperature using the HVC color model. Uses the temperature derived from the sensor 4 image to select the hue and the brightness from the histogram equalized other image to select the value and chroma. The HVC color model attempts to ensure that different colors at the same value will appear to the eye to be the same brightness and the spacing between colors representing each degree will appear to the eye to be similar. Bright areas are completely unsaturated in this model.
HVCT Similar to HVC, but with blue water and with colors more indicative of land temperatures.
SEA Creates a false color image from NOAA APT images based on sea surface temperature. Uses the sea surface temperature derived from just the sensor 4 image to color the image. Land appears black and cold high cloud will also appear black. The sea surface temperature may be incorrect due to the presence of low cloud, or of thin or small clouds in the pixel evaluated, or from noise in the signal.
THERM Produces a false color image from NOAA APT images based on temperature. Provides a good way of visualizing cloud temperatures.
VEG Requires the rarely available NOAA APT sensor 1 and 2 images (seen during the test phase after satellite launch). A vegetative index is built up and this is used so that land will be colored green, water dark blue, and clouds white. Output is not temperature normalized.
HISTEQ Histogram equalization is performed.
CONTRAST Contrast enhancement is is performed.
INVERT Creates a grayscale negative, setting black to white and white to black.
BW Creates a black and white image, setting darker pixels to black and lighter pixels to white.