Editing False color (section)

===Pseudocolor===
A '''pseudocolor''' image (sometimes styled '''pseudo-color''' or '''pseudo color''') is derived from a [[grayscale|grayscale image]] by mapping each [[Luminous intensity|intensity value]] to a color according to a table or function.<ref>{{cite web|url=http://neuron2.net/pseudocolor/pseudocolor.html|archive-url=https://web.archive.org/web/20100611221615/http://neuron2.net/pseudocolor/pseudocolor.html|archive-date=2010-06-11 |title=Pseudocolor Filter for VirtualDub |publisher=Neuron2.net |access-date=2012-09-01}}</ref> Pseudo color is typically used when a single channel of data is available (e.g. temperature, elevation, soil composition, tissue type, and so on), in contrast to false color which is commonly used to display three channels of data.<ref name="Mars Art Gallery Articles"/>

Pseudocoloring can make some details more visible, as the [[Color difference|perceived difference]] in [[color space]] is bigger than between successive gray levels alone. On the other hand, the color mapping function should be chosen to make sure the [[lightness]] of the color is still monotonic, or the uneven change would make it hard to interpret levels, for both normal and colorblind viewers. One offender is the commonly-used "rainbow" palette, with a back-and-forth change in lightness. (See also {{section link|Choropleth map|Color progression}}.)<ref>{{cite web |last1=Stauffer |first1=Reto |title=Somewhere over the Rainbow |url=http://hclwizard.org/#somewhere-over-the-rainbow |website=HCL Wizard |access-date=14 August 2019 |language=en}}</ref>

A typical example for the use of pseudo color is [[thermography]] (thermal imaging), where [[infrared camera]]s feature only one spectral band and show their grayscale images in pseudo color.
{{multiple image
| align     = center
<!-- Header -->
| header            = Examples of encoding temperature with pseudo color:
<!-- Image 1 -->
| width1    = 170
| image1    = Passivhaus thermogram gedaemmt ungedaemmt.png
| caption1  = Thermogram of a [[passive house]] in the foreground and a traditional building in the background. There is a color to temperature key on the right.
<!-- Image 2 -->
| width2    = 174
| image2    = ParowozIR.jpg
| caption2  = Thermal image of a [[steam locomotive]] using pseudocolor encoding – yellow/white indicates hot and red/violet indicates cool.
<!-- Image 3 -->
| width3    = 171
| image3 = Stsheat.jpg
| caption3 = This pseudocolor image shows the results of a computer simulation of temperatures during [[Space Shuttle]] reentry. Areas reaching 3,000 °F (1,650 °C) can be seen in yellow.
}}

Another familiar example of pseudo color is the encoding of [[elevation]] using [[hypsometric tints]] in physical [[Cartographic relief depiction|relief maps]], where negative values (below [[sea level]]) are usually represented by shades of blue, and positive values by greens and browns.
{{multiple image
| align     = center
<!-- Header -->
| header = Examples of encoding elevation with pseudo color:
<!-- Image 1 -->
| width1     = 138
| image1    = Pacific elevation.jpg
| caption1  = An elevation map of the [[Pacific Ocean]], showing ocean floor in shades of blue and land in greens and browns.
<!-- Image 2 -->
| width2     = 170
| image2    = Kasei Valles topo.jpg
| caption2  = This color-coded elevation relief map indicates the result of floods on [[Mars]]. There is a color to elevation key on the bottom.
<!-- Image 3 -->
| width3     = 177
| image3    = Moon worldwind.jpg
| caption3  = The [[Moon]] with hypsometric tints of red for the highest points and purple for the lowest.
}}

Depending on the table or function used and the choice of data sources, pseudocoloring may increase the information contents of the original image, for example adding geographic information, combining information obtained from infrared or ultra-violet light, or other sources like [[Magnetic resonance imaging|MRI]] scans.<ref>{{cite journal |url=http://www.viskom.oeaw.ac.at/~leon/docs/paper.ps |archive-url=https://web.archive.org/web/20110706085353/http://www.viskom.oeaw.ac.at/~leon/docs/paper.ps |archive-date=2011-07-06 |title=Pseudo-colored visualization of EEG-activities on the human cortex using MRI-based volume rendering and Delaunay interpolation |journal=Medical Imaging 1995: Image Display |volume=2431 |pages=460–469 |access-date=2009-03-18 |author=Leonid I. Dimitrov |editor-first1=Yongmin |editor-last1=Kim |year=1995 |bibcode=1995SPIE.2431..460D |doi=10.1117/12.207641 |citeseerx=10.1.1.57.308 |s2cid=13315449 }}</ref>

{{multiple image
| align     = center
<!-- Header -->
| header            = Examples of overlaying additional information with pseudo color:
<!-- Image 1 -->
| width1    = 152
| image1    = Moon Crescent - False Color Mosaic.jpg
| caption1  = This image shows compositional variations of the Moon overlaid as pseudo color.
| alt1  = This image shows compositional variations of the Moon overlaid as pseudocolor. Bright pinkish areas are highlands materials, blue to orange shades indicate volcanic lava flows. Recent impacted soils are represented by light blue colors; the youngest craters have prominent blue rays extending from them.
<!-- Image 2 -->
| width2    = 170
| image2    = MR_Knee.jpg
| caption2  = A grayscale MRI of a knee – different gray levels indicate different tissue types, requiring a trained eye.
<!-- Image 3 -->
| width3    = 184
| image3    = Knee MRI 113035 rgbcb.png
| caption3  = A pseudocolor MRI of a knee created using three different grayscale scans – tissue types are easier to discern through pseudo color. 
}}

A further application of pseudocoloring is to store the results of image elaboration; that is, changing the colors in order to ease understanding an image.<ref>{{Cite book|last1=Setchell|first1=C. J.|last2=Campbell|first2=N. W.|title=7th International Conference on Image Processing and its Applications |date=July 1999|chapter=Using colour Gabor texture features for scene understanding|language=en|volume=1999|pages=372–376|doi=10.1049/cp:19990346|isbn=0-85296-717-9 |s2cid=15972743 }}</ref>