4. LUTs

LUT Options

Available options for LUTs can vary depending on how they are used by a specific component.

In general, the options available are:

• Scale Mode (linear, LN, LOG10)

  • LN and LOG10 are non-linear scaling used to provide improved contrast at low ranges, while compressing high ranges

  • LOG10 provides a stronger non-linear histogram shift than "LN"

• Range (min, max)

  • • Note the gamma spectroscopy histogram has a fixed range of 0.0 - 2000.0 keV applied presently.

• Invert

  • • Invert reverses the order of the colors, it does not invert the RGB values.

• Discretize

  • • Decreases the color depth of a LUT, which in some situations can make larger-scale patterns more visible.

Specific LUT Information

• Rainbow

  • If you've seen the film "Predator", you know what this is.

  • General 3-color LUT.

  • Best in cases where each color band highlights a distinct range of data

  • Weak in cases where data ranges bleed across color bands

  • From ImageJ's "Rainbow RGB"

• Safecast

  • Copy of Safecast's palette used on their web map

  • Isothermic palette; clear breakpoints at 0.2, 0.5, 1.0, 5.0, and 10.0.

  • These breakpoints are fixed and the scale is static

  • Isothermic palettes excel at highlighting bands of data with greater contrast, but do so at the cost of not showing relative intensity in that band well (or at all).

  • From Safecast

• Fire (default)

  • This type of palette is sort of the new standard in thermal cameras (at least the building inspection ones)

  • This emulates how hot liquid metal looks to the human eye (ie, black body radiation)

  • Less prone to banding effects than rainbow

  • Somewhat better contrast at low intensities than rainbow

  • From ImageJ

    • (image credit: FLIR)

• Green Fire Blue

  • Rainbow palette with somewhat higher brightness and lower contrast

  • From ImageJ

• Smart

  • Isothermic palette

  • General idea is, make anything around normal levels grayscale, and only color in the hotspots

  • From ImageJ

• Thallium

  • Monochrome green palette

  • Provides better contrast at higher ranges, by sacrificing contrast at lower ranges (black crush)

  • From ImageJ

• Arctic

  • Higher brightness rainbow palette

  • Similar to (but distinct from) ImageJ's "cool" LUT

• White Hot

  • Simple luminance scaling based on intensity

  • Extremely common palette used pretty much everywhere

  • Lack of chroma makes it have less visible contrast to the human eye

• Black Hot

  • Inverse of white hot.

  • Shows lower intensities better than white hot, generally.

  • Again, generally less contrast than colored palettes.

• ENVG Color Fusion

  • Variant of the "Smart"-type LUT, with better brightness at lower ranges

  • Green and then breaks to orange -> yellow

  • This is a LUT I created based on one of the AN/PSQ-20's display modes

    • (image credit: TNVC)

• Gem

  • Darker version of Iron, mostly

  • From ImageJ

• Isotherm

  • Pretty standard white-hot with red-high and blue-low isotherm bands

  • Good at highlighting extremes

  • Used to find dew points in thermal cameras

  • Similar to (but distinct from) ImageJ's "HiLo" LUT

• Rainbow HC

  • A rainbow variant with 6 colors

  • Increased bands cover large differences better, but it is excessive for limited ranges

• Cherenkov

  • A monochrome blue palette with a higher minimum brightness

  • I modeled this after the visual appearance of Cherenkov radiation

    • (image credit: Argonne National Laboratory)

  • Similar to (but distinct from) ImageJ's "Cyan Hot" LUT

• Firestorm

  • Similar to Cherenkov, intent was a palette with increased minimum brightness

  • Similar to (but distinct from) ImageJ's "Red Hot" LUT

• RGB Ramps

  • Very heavily banded palette

  • Situationally useful for increased contrast in small ranges of data

• Many LUTs have been converted directly from ImageJ. Don't thank me, thank the NIH.

LUT Example: X-Ray of Canine Lateral Abdomen

The original image is the first. The other images have been colored using ImageJ's LUTs that are also available for mapping in Geiger Bot.

Some are built-in to ImageJ, the others I have created and imported. (using the NucMed plugins)

While you're looking at map data and not a radiograph, this should at least be a good visual example of the differences between some of the LUTs. Other than the LUT being applied, they are unaltered.