Matlab Colormap Range

5 is show in the bar, while the colormap covers -2 to 2 (so this could be your data range, which you record before the scaling). The values are not case sensitive. Since we want the regions of left-to-right flow (positive speed) to range from yellow to dark red, we can delete the cyan node pointer. Vector Calculus Examples Using MATLAB MATLAB can evaluate and plot most of the common vector calculus operations that we have previously discussed. If no figure exists, then the number of rows is equal to the default length of 256. A colormap is matrix of values between 0 and 1 that define the colors for graphics objects such as surface, image, and patch objects. As I understood, caxis only allows to set minimum or maximum range. Colormaps in MATLAB are always m-by-3 arrays of double-precision floating-point numbers in the range [0, 1]. Colormaps for Terrain Data. How can one customize "colormap" in matlab? In an image I have to set colormap as gray , and I need the min color to be white and max color to be gray. The documentation for the MATLAB colormap function provides complete information about specifying colormap matrices, and includes a complete list of the available colormap functions. over the range -2 x 2, -2 y 3, create matrix Z using the statements. If the cmap kwarg is given but boundaries and values are left as None. Figure 3 shows the jet color map from Matlab, which is a classical rainbow map with all its pros and cons. Many MATLAB ® functions expect pixel values to be in the range [0, 1] for truecolor images of data type single or double. Thank you, but that's not what I'm looking for. Si establece el mapa de colores para la figura, los ejes y los gráficos de la figura utilizan el mismo mapa de colores. I need to change the colorbar range, from a normal to a logarithmic one, to improve visual the range of the change of my output data through time along the distance X. For example, here is a surface plot with the default color scheme. If no figure exists, then the number of rows is equal to the default length of 256. 0]) then you would only see half of the colours in the colormap. In my plot the 80% of the image has one color, because the change of Z data occurred only in a specific area of X-Y. Using color palette tables as Matlab colormaps. If you omit the argument, imhist uses a default value of n = 256 if I is a grayscale image, or n = 2 if I is a binary image. I have data mostly between 1 and 10, but with a small percentages of values from 30 to 180. Sometime later, I came across some material by Peter Kovesi about designing perceptually uniform colormaps (or colourmaps, as Peter writes it). I have a n x m matrix with values in the range 0. Colormaps in MATLAB are always m-by-3 arrays of double-precision floating-point numbers in the range [0, 1]. By default (with CDataMapping property is set to 'scale'), CData is scaled to "map" to colormap range. Axis Properties Select the Axis Properties tab to show the axis property parameters, which control labeling and positioning. limits is a two-element vector of the form [cmin cmax]. This does not affect where the actual contor lines go, though. To view a contour plot of the function. Fitting error. This colormap is useful for adding an "electronic" look to. brighten(beta) shifts the intensities of all colors in the current colormap in the same direction. Colors and colorscales (ordered progressions of colors) are invaluable for representing geographic variables on maps, particularly when you create terrain and thematic maps. Control Colormap Limits. If X or Y is irregularly spaced, contour calculates contours using a regularly spaced contour grid, then transforms the data to X or Y. 16 responses to “ A good divergent color palette for Matlab ” Hboll March 21, 2012 at 2:57 pm · · Reply → Aesthetically, I agree that the colors employed in the LB colormap are indeed quite pleasing, but its not suitable for accurately displaying land/sea boundary. This means that it is possible to create a colormap where particular colors correspond to particular values in the plotted data, but again this requires knowing something about the plotted values, how they are plotted, and then adjusting/creating a colormap to suit this. In other parts of the range, jet tends to obscure small variations. % Define a colormap that consists of 4 separate colormaps. MATLAB sets the color limits to span the range of the image data, which is 1 to 192: caxis ans = 1 192 The blue color of the ocean is the first color in the colormap and is mapped to the lowest data value (1). Colormaps in MATLAB are always m-by-3 arrays of double-precision floating-point numbers in the range [0, 1]. bone is a grayscale colormap with a higher value for the blue component. HSV — MATLAB calculates values in the new colormap by linearly interpolating the hue, saturation, and value coordinates. Isn't as good as the. Each row in the array contains the red, green, and blue intensities for a specific color. How can one customize "colormap" in matlab? In an image I have to set colormap as gray , and I need the min color to be white and max color to be gray. Set color map color range. If omitted, a default increment of 100 is used. See our Version 4 Migration Guide for information about how to upgrade. In most graphics file formats, colormaps are stored as integers, but MATLAB does not support colormaps with integer values. So you can use 1/255[255,0,0] to get the color of red to use as a color in MATLAB. Just the range of values used to assign colors. Therefore, a positive value in the divergence color map represents an increase in SampEn and vice versa. In other parts of the range, jet tends to obscure small variations. If you are going to change the plotted data or make a new plot and want to control the color range, then read about the caxis. In response to a preview of MATLAB R2014b, a user complained that the parula colormap was "noisy. I solved the problem by creating 2 axes. Hi , I want to change colorbar's color in some particular value interval. Posted on December 18, 2015 in I'll begin my series of Matlab code posts with one of the functions that I use most often in my own work: cptcmap. Parula has replaced jet as the default colormap in R2014b, which was released earlier this month. MATLAB Function Reference To view a contour plot of the function. Get another monotonic colormap and see other colormap choices. So instead of scaling the colormap you scale your data and fit the colorbar to that. Does anyone know about rescaling colormap in MATLAB between [0, 1]? I have a colormap (say hsv) and caxis are reported between [-32656, 32657]. help required using colormap function in matlab. finding rbg color values from color map. The smallest value in your data maps to the first row in the colormap, and the largest value maps to the last row in the colormap. 0548 as white (or whatever the largest value in the colormap is set to), and any that are smaller than 0. Optionally, you can also use contourcmap to add and label a colorbar similarly to the MATLAB® colorbar function. You can view a list of all inbuilt colormaps in the colormap documentation, or you can find many excellent colormaps on MATLAB File Exchange too. The oxy colormap is sequential for most of the colormap, representing the normal range of oxygen saturation in ocean water, and diverging 80% of the way into the colormap to represent a state of supersaturation. If you were hoping that MATLAB remembered the name of the colormap in use sorry, it doesn't do that. By default, the legend annotates the current axes. If it is e. In response to "MATLAB image display - autoscaling values with imshow," MATLAB Answerer Extraordinaire ImageAnalyst posted this comment:. Here we defined the colors directly as rgb values in the range of 0. 5 to become white color, how can I do this?. It is represented by a [Nx3] matrix, where N is the number of colors available in it. If X is of class double, the imwrite function offsets the values in the array before writing, using uint8(X-1). Note that most image file formats do not support colormaps with more than 256 entries. help required using colormap function in matlab. get_color_rgba - chooses an RGB triplet or RGBA quadruplet for a scalar value, given a color map and a range of values. : MATLAB (6307 members) How to adjust colorbar range in a matlab plot Avg12 (Computer) 1 replies (5 Mar 19) 5 Mar 19. This will make the cmin = -5 and cmax = 8. MATLAB supports a number of colormaps. The data I have is 1200 x 1600 monochrome png file (0-255). For glare analysis, strict calibration is necessary to extract accurate luminous maps to achieve reliable glare results. Indexed Images. Imwrite and colormap showing strange behaviour (self. If it is e. py, which is not the most recent version. That turns everything above 150 to red and everything below 100 to blue. A rainbow colormap is based on the. Axis Properties Select the Axis Properties tab to show the axis property parameters, which control labeling and positioning. Looking at the Jet colormap (the old Matlab default) in this way the problem becomes clear. over the range -2 x 2, -2 y 3, colormap cool Smoothing Contour Data. Tags: colormap , configuration , data , image , load , palette Interpolation of heat maps. In my plot the 80% of the image has one color, because the change of Z data occurred only in a specific area of X-Y. Many types of combinations you create, it is the feature of MATLAB to map the full range of your data to the colormap. Control Colormap Limits. So if you somehow convert the CData, colormap to index image, you can then convert indexed image to RGB image using ind2rgb function. I have a n x m matrix with values in the range 0. Start the colormap editor using the colormapeditor command. The 16 contour lines have been drawn for that. – The second input argument [0, 1] to imagesc specifies the desired intensity range. Parula has replaced jet as the default colormap in R2014b, which was released earlier this month. I used imagesc with colormap ([1 0 0; 0 1 0]). Here we defined the colors directly as rgb values in the range of 0. If you do not specify a size, MATLAB creates a colormap the same size as the current colormap. In response to a preview of MATLAB R2014b, a user complained that the parula colormap was "noisy. % The colormap can only be 256 rows long (otherwise it repeats - you can't assign them). Back to Climate Data Tools Contents. Values inbetween those two are, again, linearly mapped. When I compare my images to those generated using the "Fastie" colormap on the infragram. (See the illustration on the following page. Thank you, but that's not what I'm looking for. For example, here is a surface plot with the default color scheme. autumn varies smoothly from red, through orange, to yellow. A colormap is matrix of values between 0 and 1 that define the colors for graphics objects such as surface, image, and patch objects. c = jet returns the jet colormap as a three-column array with the same number of rows as the colormap for the current figure. limits is a two-element vector of the form [cmin cmax]. In most graphics file formats, colormaps are stored as integers, but MATLAB does not support colormaps with integer values. So if you somehow convert the CData, colormap to index image, you can then convert indexed image to RGB image using ind2rgb function. Select the colormap of your choice or you can customize it shown in figure 5. c = lines returns the lines colormap as a three-column array with the same number of rows as the colormap for the current figure. MATLAB® uses a default color scheme when it displays visualizations such as surface plots. Indexed Images. If no figure exists, MATLAB creates one. If X or Y is irregularly spaced, contour calculates contours using a regularly spaced contour grid, then transforms the data to X or Y. % So make each image only a portion of the 256 gray levels. (See Examples for an illustration. This colormap is useful for adding an "electronic" look to grayscale images. " It turned out that parula had revealed amplitude variation in the user's data that the jet colormap had obscured. If it is e. If no figure exists, then the number of rows is equal to the default length of 256. c = jet returns the jet colormap as a three-column array with the same number of rows as the colormap for the current figure. Range of the data was (50-125). over the range -2 x 2, -2 y 3, colormap cool Smoothing Contour Data. When images are read in using imread, MATLAB stores the data as 8-bit integers, or integers that can range from 0 to 255. c = bone returns the bone colormap as a three-column array with the same number of rows as the colormap for the current figure. Posted on December 18, 2015 in I'll begin my series of Matlab code posts with one of the functions that I use most often in my own work: cptcmap. The color map editor displays the current figure' s colormap, as shown in the following picture. For example, here is a surface plot with the default color scheme. limits is a two-element vector of the form [cmin cmax]. 1 to 1000 then you can easily create a colourmap of size 1000 (or 1001 to include special NaN handling), but if your range is up to e. I used imagesc with colormap ([1 0 0; 0 1 0]). Learn more about color, colormap, 3d plots. how to set color range for color in color bar. This entry must be a scalar value. % The colormap can only be 256 rows long (otherwise it repeats - you can't assign them). MATLAB sets the color limits to span the range of the image data, which is 1 to 192: caxis ans = 1 192 The blue color of the ocean is the first color in the colormap and is mapped to the lowest data value (1). I am using Matlab 7. Control Colormap Limits. There are many ways to make maps in Matlab. First, create a script that will map the range (0,1) to values in the RGB spectrum. In response to a preview of MATLAB R2014b, a user complained that the parula colormap was "noisy. Here's how one can use those colors in MATLAB. In Matlab release R2018 a new memory layout for complex numbers was introduced (i. In my case that was the 28th row (id = 28). MATLAB versions >= 6. How can one customize "colormap" in matlab? In an image I have to set colormap as gray , and I need the min color to be white and max color to be gray. This entry must be a scalar value. the Interleaved Complex API). Fitting error. In order to apply the colormap, we now can simple write. % The colormap can only be 256 rows long (otherwise it repeats - you can't assign them). I don't know why the limits are set in a weird way to some previous axis drawn data min and max, regardless the values I specify in caxis:. lbmap has four colormaps for the colorblind and is really easy to use. For example, here is a surface plot with the default color scheme. 5 to become white color, how can I do this?. I have data mostly between 1 and 10, but with a small percentages of values from 30 to 180. T he surface / surf plot in MATLAB can visualize data in 3D. To see this you need to look no further than the ubiquity of MATLAB’s former default colormap jet and the popularity of the MATLAB-inspired plotting package matplotlib in Python, the tool du jour for data scientists. Last week I showed you the new MATLAB colormap, parula. 10,000 then a colourmap of that size is rather infeasible and way beyond what the human eye can distinguish. Create a 25x 25 matrix of random integers in the range from 1 to 25. When you write an indexed image using imwrite, MATLAB automatically converts the values if necessary. For many types of visualizations you create, MATLAB ® maps the full range of your data to the colormap by default. The intensities must be in the range [0,1]; for example, [0. I want to have this scale normalized between 0 and 1. Here is my code:. This entry defines the length of the colormap. I transformed most of the colormaps used in the sc-package for Matlab into pgfplots format (see attached patch). By default, the legend annotates the current axes. To change the colormap go to Edit -> Colormap of the current figure and this will open a new window as shown below: Alternatively, one can use the command " colormapeditor " in the matlab command window. create colormap from matrix value. To view a contour plot of the function. For example, here is a surface plot with the default color scheme. Learn more about color, colormap, 3d plots. This will scale the colormap data range between 0. All values in the colormap indexing array that are less than or equal to cmin map to the first row in the colormap. help required using colormap function in matlab. Each color is coded with three values corresponding its relative levels of red, green and blue. Colors and colorscales (ordered progressions of colors) are invaluable for representing geographic variables on maps, particularly when you create terrain and thematic maps. imshow uses the default display range for the image data type and optimizes figure, axes, and image object properties for image display. Is it possible to get the range of RGB color values they seem to represent (in a 64x3 matrix) instead of values from 0 to 1?. legend associates strings with the objects in the axes in the same order that they are listed in the axes Children property. MATLAB® uses a default color scheme when it displays visualizations such as surface plots. Do this like so:. !LinearSegmentedColormap. 5 • Consists of a data matrix, I, whose values represent intensities within some range. : MATLAB (6307 members) How to adjust colorbar range in a matlab plot Avg12 (Computer) 1 replies (5 Mar 19) 5 Mar 19. Good old "gray": Our new colormaps. I also want to draw a colorbar beside the axis I draw the data. c = gray returns the gray colormap as a three-column array with the same number of rows as the colormap for the current figure. If it works correctly with imagesc but not when writing to an image with imwrite then your custom colormap must be implemented in such a way that values above ~60 are outside of its range, forcing other values to get a color of [0,0,0] (i. Start the colormap editor using the colormapeditor command. I have no idea what data you have, how it is structured, and how it correlates to the two seemingly unrelated plots that you have shown. MATLAB sets the color limits to span the range of the image data, which is 1 to 192: caxis ans = 1 192 The blue color of the ocean is the first color in the colormap and is mapped to the lowest data value (1). You can change the color scheme by specifying a colormap. The intensities must be in the range [0,1]; for example, [0. Each MATLAB figure window has a colormap associated with it. The colormap is a three-column 2-D matrix whose length is equal to the number of colors that are defined. legend positions the legend based on a variety of factors, such as what objects the legend obscures. Each MATLAB figure window has a colormap associated with it. The values are not case sensitive. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of a color. This is MATLAB(R)'s new default colormap. I want the full range of the colormap displayed on the image; just the colorbar showing a fraction of the range. Control Colormap Limits. Then when you call caxis, you get rid of any color distinction above 2 or below -2 (>2 all have same color, <-2 all have same color). I can color the points according to a third vector z by turning on colormap and colorbar (scatter(X,Y,S,C) and use z in place. The values in this 2-D matrix range from 0 - 10,000. As I understood, caxis only allows to set minimum or maximum range. Otherwise, the resultant colormap contains ten colors. To compile these files on Windows with a gcc (mingw) compiler rename the two files and. Thus, you can use this colormap to make your chart colors match the output of the plot. the Interleaved Complex API). Thank you, but that's not what I'm looking for. Colormap function. How can one customize "colormap" in matlab? In an image I have to set colormap as gray , and I need the min color to be white and max color to be gray. I want to set the range in my log plot to 14 to the maximum value. I'm am able to generate a countour plot that has levels image one, which gave me the countours percent of max. When viewed from within the Matlab figure window (dedicated figure windows, or within plotbrowser, either way), I see exactly what I expect. This will scale the colormap data range between 0. Control Colormap Limits. By default, the legend annotates the current axes. The intensities are in the range [0,1], and the color scheme matches the default ColorOrder property of the Axes. MATLAB Help • MATLAB Help is an extremely powerful assistance to learning MATLAB • Help not only contains the theoretical background, but also shows demos for implementation • MATLAB Help can be opened by using the HELP pull-down menu. The smallest value in your data maps to the first row in the colormap, and the largest value maps to the last row in the colormap. I want the full range of the colormap displayed on the image; just the colorbar showing a fraction of the range. caxis(limits) sets the colormap limits for the current axes. Colormap¶ class matplotlib. So you can use 1/255[255,0,0] to get the color of red to use as a color in MATLAB. Learn more about color, colormap, 3d plots. The examples in MatLab help deal with having multiple axes, and setting CLim differently for each axes after concatonating colormaps. Optionally, you can also use contourcmap to add and label a colorbar similarly to the MATLAB® colorbar function. 4 you only need applyColorMap() to apply a colormap on a given image. Change the Colormap of Your Image: Select the custom colormap option shown in fig. Colormap (name, N=256) [source] ¶. Using caxis like this, all values outside the range [minValue maxValue] will be coloured with the lowest or highest value in the colormap, respectively. Learn more about imagesc, colormap. With this colormap, anything in grayscale is probably not a plant. Bauhaus, Art Deco, Brutalist, MATLAB, ggplot? Matlab has made a mark on the scientific visualization world. Here is my code:. It is also useful by itself for showing a colormap. If no figure exists, then the number of rows is equal to the default length of 64. Colormaps are three-column arrays containing RGB triplets in which each row defines a distinct color. Please, if anyone knows how to solve this issue let me know. A rainbow colormap is based on the. Specifies the contrast limits in the input RGB image or colormap that you want to map to values in the output image or colormap. Well, all of the MATLAB colormap functions take an optional input argument specifying the number of colors to use. The colorbar function displays the current colormap in the current figure and resizes the current axes to accommodate the colorbar. Matlab comes with a decent selection of colormaps. over the range -2 x 2, -2 y 3, colormap cool Smoothing Contour Data. The documentation for the MATLAB colormap function provides complete information about specifying colormap matrices, and includes a complete list of the available colormap functions. If those are too many colormaps, please add at least the 'jet' colormap, as it is Matlab's default and thus quite commonly used. If it is e. You can change the color scheme by specifying a colormap. 此 matlab 函数 在当前坐标区或图的右侧显示一个垂直颜色栏。颜色栏显示当前颜色图并指示数据值到颜色图的映射。. red-yellow-green-cyan-blue-pink-magenta color map formed by changing the hue component in the HSV color space; based on colormap of the same name in Matlab, who recommend it for used in plotting periodic data (that is, in which the maximum magnitude and the minimum magnitude are equivalent). This means that it is possible to create a colormap where particular colors correspond to particular values in the plotted data, but again this requires knowing something about the plotted values, how they are plotted, and then adjusting/creating a colormap to suit this. If no figure exists, then the array contains 64 rows. I am new to colormaps in MATLAB, but I know their range of values go from 0 to 1 in a 64x3 matrix. The data I have is 1200 x 1600 monochrome png file (0-255). Each MATLAB figure window has a colormap associated with it. Hi , I want to change colorbar's color in some particular value interval. colormap(C/255); % in matlab import matplotlib as mpl # in python cm = mpl. Problem with colormap command using hsv. In response to a preview of MATLAB R2014b, a user complained that the parula colormap was "noisy. Use these for all condition tests in loops and similar, and use the old | and & for element-by-element logical operations. % check out the range of colored data % use the j colormap to cover data. By default M=64. In my plot the 80% of the image has one color, because the change of Z data occurred only in a specific area of X-Y. If no figure exists, then the number of rows is equal to the default length of 256. Figure 7 shows the divergence color map for the edges obtained using the difference between SampEn at scale ten and scale two. In Matlab, the colors are coded between 0 and 1. py, which is not the most recent version. Create a custom colormap by dragging points on the RGB intensity curves. caxis(limits) sets the colormap limits for the current axes. I transformed most of the colormaps used in the sc-package for Matlab into pgfplots format (see attached patch). Therefore, a positive value in the divergence color map represents an increase in SampEn and vice versa. In MATLAB the color lookup table is called the colormap. If it is e. colorbrewer is the gold standard for colormaps, by cynthia brewer. set palette @MATLAB. Scale the values to the full range of the current colormap by setting the CDataMapping property to 'scaled' when creating the image. MATLAB® uses a default color scheme when it displays visualizations such as surface plots. This means that it is possible to create a colormap where particular colors correspond to particular values in the plotted data, but again this requires knowing something about the plotted values, how they are plotted, and then adjusting/creating a colormap to suit this. Setting Ticks in a Colorbar. 5 is show in the bar, while the colormap covers -2 to 2 (so this could be your data range, which you record before the scaling). MATLAB Input and Output MATLAB Input and Output Matlab/Simulink Dipl. Is it possible to get the range of RGB color values they seem to represent (in a 64x3 matrix) instead of values from 0 to 1?. After the MATLAB R2014b release, I wrote several blog posts (Part 1, Part 2, Part 3, and Part 4) about the new default colormap, parula, that was introduced in that release. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of a color. To see this you need to look no further than the ubiquity of MATLAB's former default colormap jet and the popularity of the MATLAB-inspired plotting package matplotlib in Python, the tool du jour for data scientists. For example I have vectors x and y with some sort of values plotted as a scatter plot. Colorbars illustrate the relationship between the colors of the colormap and your data. legend associates strings with the objects in the axes in the same order that they are listed in the axes Children property. red-yellow-green-cyan-blue-pink-magenta color map formed by changing the hue component in the HSV color space; based on colormap of the same name in Matlab, who recommend it for used in plotting periodic data (that is, in which the maximum magnitude and the minimum magnitude are equivalent). tif file into a. A colormap is an array of colors that are indexed and then mapped to values. Create a custom colormap by dragging points on the RGB intensity curves. Setting Ticks in a Colorbar. A colorbar displays the current colormap along with numerical rulings so that the color scale can be interpreted. UK Biobank is currently in the process of developing the worlds largest multimodal imaging. over the range -2 x 2, -2 y 3, create matrix Z using the statements. The rows of zeros do not appear on the colorbar, since it is a copy without the rows of zeros. Colormaps define the color scheme for many types of visualizations, such as surfaces and patches. caxis(limits) sets the colormap limits for the current axes. Display the image of your matrix. The following section provides an example for applying colormaps and colorbars to maps. HSV — MATLAB calculates values in the new colormap by linearly interpolating the hue, saturation, and value coordinates. If X is of class uint8 or uint16, imwrite writes the actual values in the array to the file. The lower values are in the beep blue range and the higher values in the reds. Problem with colormap command using hsv. For glare analysis, strict calibration is necessary to extract accurate luminous maps to achieve reliable glare results. colormap map establece el mapa de colores de la figura actual como uno de los mapas de colores predefinidos. For many types of visualizations you create, MATLAB ® maps the full range of your data to the colormap by default. Colormaps in MATLAB are always m-by-3 arrays of double-precision floating-point numbers in the range [0, 1]. A % Matlab's command line is a little like a standard shell:. Scale the values to the full range of the current colormap by setting the CDataMapping property to 'scaled' when creating the image. I'm doing some plotting in Matlab where I'm using a third variable of data as a color. % So make each image only a portion of the 256 gray levels. Values must be in the range [0 1]. Colormap function. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of a color. In other parts of the range, jet tends to obscure small variations. Indexed Images. 5(e) Controlling the Limits of Colormap. legend associates strings with the objects in the axes in the same order that they are listed in the axes Children property. In between it passes trough light blue green, yellow, orange. Learn more about matlab, colour, graphing, colormap, plot3 MATLAB bearing in mind that value outside the caxis range are. When I took a course in grad school on statistical image processing, I saw a very interesting plot where data is shown as a surf plot and underneath, on the ground or x-y plane, an image is shown. The contourcmap function creates a colormap that has color changes at a fixed value increment. Optionally, you can also use contourcmap to add and label a colorbar similarly to the MATLAB® colorbar function. If no figure exists, then the number of rows is equal to the default length of 64. The values are not case sensitive. In my plot the 80% of the image has one color, because the change of Z data occurred only in a specific area of X-Y. Subtle issue here: the Lo value you supply is greater than the data minimum, or the High value you supply is less than the data minimum, then the numeric mapping (before the conversion to logical or uint8 or uint16) will have some values that are negative, or greater than the number of entries in the color map. The colormap is a three-column 2-D matrix whose length is equal to the number of colors that are defined. I need to change the colorbar range, from a normal to a logarithmic one, to improve visual the range of the change of my output data through time along the distance X. autumn varies smoothly from red, through orange, to yellow. % check out the range of colored data % use the j colormap to cover data. I love getting short, concise questions from fellow MATLAB users. " It turned out that parula had revealed amplitude variation in the user's data that the jet colormap had obscured. A discussion of the relationship and interplay of caxis(), CLim, and the values you can pass in inside the brackets to imshow() or imagesc() might be useful. The argument to be passed in is the name of the colormap (default is 'jet'). % So make each image only a portion of the 256 gray levels.