--- title: "LinearGradientImage" language: "en" type: "Symbol" summary: "LinearGradientImage[gcol] returns an image with values linearly changing from left to right based on gradient color gcol. LinearGradientImage[{pos1, pos2} -> gcol] returns an image where the gradient starts at pos1 and ends at pos2. LinearGradientImage[..., size] returns a linear gradient image of the specified size. LinearGradientImage[..., size, type] gives an image converted to the specified type." keywords: - gradient image - color shades - linear gradient image - vertical gradient image - horizontal gradient image - diagonal gradient image - color gradient - linear color gradient canonical_url: "https://reference.wolfram.com/language/ref/LinearGradientImage.html" source: "Wolfram Language Documentation" related_guides: - title: "Creating & Importing Images" link: "https://reference.wolfram.com/language/guide/CreatingAndImportingImages.en.md" related_functions: - title: "RadialGradientImage" link: "https://reference.wolfram.com/language/ref/RadialGradientImage.en.md" - title: "Blend" link: "https://reference.wolfram.com/language/ref/Blend.en.md" - title: "ConstantImage" link: "https://reference.wolfram.com/language/ref/ConstantImage.en.md" - title: "RandomImage" link: "https://reference.wolfram.com/language/ref/RandomImage.en.md" - title: "Image" link: "https://reference.wolfram.com/language/ref/Image.en.md" - title: "ColorData" link: "https://reference.wolfram.com/language/ref/ColorData.en.md" - title: "GradientFilter" link: "https://reference.wolfram.com/language/ref/GradientFilter.en.md" --- # LinearGradientImage LinearGradientImage[gcol] returns an image with values linearly changing from left to right based on gradient color gcol. LinearGradientImage[{pos1, pos2} -> gcol] returns an image where the gradient starts at pos1 and ends at pos2. LinearGradientImage[…, size] returns a linear gradient image of the specified size. LinearGradientImage[…, size, "type"] gives an image converted to the specified type. ## Details and Options * ``LinearGradientImage`` constructs a 2D or 3D image with constant gradient along a direction derived from the input specification. * Color scheme specification ``gcol`` can be any of the following: | | | | --------------- | ---------------------------------------------------------- | | {col1, col2, …} | blend of multiple color directives coli | | "name" | ColorData["name"] | | f | function f that returns a color based on a scalar distance | * The argument passed to the function ``f`` is by default the normalized distance between a pixel and the line going through ``pos1``, perpendicular to ``pos2 - pos1``. * Position specification ``posi`` can be any of the following: | | | | ------------------- | ------------------------------------------------------------------------------------------ | | {x, y} or {x, y, z} | absolute pixel position | | Left, Right | $x$ axis in 2D and 3D | | Bottom, Top | $y$ axis in 2D, $z$ axis in 3D | | Front, Back | $y$ axis in 3D | | Center | center alignment | | {posx, …} | a list of named positions | * Positions that are not constrained are taken to be centered. * By default, positions are assumed to be in the standard image coordinate system. [image] * The ``size`` specification can be one of the following: | | | | ---------------------- | ----------------------------- | | side | 2D image of size {side, side} | | {width, height} | 2D image size specification | | {width, depth, height} | 3D image size specification | * The default ``size`` is ``{150, 150}`` for 2D images and ``{64, 64, 64}`` for 3D images. * ``LinearGradientImage[]`` is equivalent to ``LinearGradientImage[{Black, White}]``. * ``LinearGradientImage`` accepts all ``Image`` and ``Image3D`` options with the following additions and changes: | | | | | --------------------- | --------- | ---------------------------------------------- | | ColorFunction | Automatic | how each pixel should be colored | | ColorFunctionScaling | True | whether to scale the argument to ColorFunction | | DataRange | Full | range of coordinates in the original image | | Padding | "Fixed" | padding scheme | * Possible settings for ``DataRange`` include: | | | | --------------------------------------------- | ------------------------------------------------------------------ | | Automatic | {{0, 1}, {0, h / w}} in 2D, {{0, 1}, {0, d / w}, {0, h / w}} in 3D | | Full | {{0, w}, {0, h}} in 2D, {{0, w}, {0, d}, {0, h}} in 3D (default) | | {{left, right}, {bottom, top}} | explicit coordinate ranges in 2D | | {{left, right}, {front, back}, {bottom, top}} | explicit coordinate ranges in 3D | ## Examples (28) ### Basic Examples (4) Linear grayscale gradient from left to right: ```wl In[1]:= LinearGradientImage[] Out[1]= [image] ``` --- Linear blend of colors from left to right: ```wl In[1]:= LinearGradientImage[{Blue, Yellow, Red}] Out[1]= [image] ``` --- Linear gradient image along a given direction: ```wl In[1]:= LinearGradientImage[{{Left, Bottom}, {Right, Top}} -> {Blue, Yellow, Red}] Out[1]= [image] ``` --- Specify the output size: ```wl In[1]:= LinearGradientImage[{Blue, Yellow, Red}, {150, 50}] Out[1]= [image] ``` ### Scope (14) #### Color Schemes (5) Linear blend of two colors: ```wl In[1]:= LinearGradientImage[{Red, Yellow}] Out[1]= [image] ``` --- Linear blend of multiple colors: ```wl In[1]:= LinearGradientImage[{Red, Blue, Green, Yellow}] Out[1]= [image] ``` --- Use a gradient color scheme: ```wl In[1]:= LinearGradientImage["Rainbow"] Out[1]= [image] ``` --- Use hue as the coloring function: ```wl In[1]:= LinearGradientImage[Hue] Out[1]= [image] ``` --- Specify a custom color function: ```wl In[1]:= LinearGradientImage[RGBColor[#, 1 - #, # / 2]&] Out[1]= [image] ``` #### Positions (6) By default, a linear gradient image from left to right is generated: ```wl In[1]:= LinearGradientImage[ColorData["Rainbow"]] Out[1]= [image] ``` --- A top-to-bottom gradient image: ```wl In[1]:= LinearGradientImage[{Top, Bottom} -> ColorData["Rainbow"]] Out[1]= [image] ``` --- A diagonal gradient image: ```wl In[1]:= LinearGradientImage[{{Left, Bottom}, {Right, Top}} -> ColorData["Rainbow"]] Out[1]= [image] ``` --- If position along one dimension is not given, center alignment is used for that dimension: ```wl In[1]:= LinearGradientImage[{Left, Top} -> ColorData["Rainbow"]] Out[1]= [image] ``` --- Left-to-right 3D gradient image: ```wl In[1]:= LinearGradientImage[{Left, Right} -> ColorData["Rainbow"], {7, 7, 7}] Out[1]= [image] ``` --- Diagonal 3D gradient image: ```wl In[1]:= LinearGradientImage[{{Left, Front, Top}, {Right, Back, Bottom}} -> ColorData["Rainbow"], {8, 5, 3}] Out[1]= [image] ``` #### Size (3) By default, a 2D image of size $\{150,150\}$ is generated: ```wl In[1]:= LinearGradientImage[Hue] Out[1]= [image] ``` --- If absolute pixel positions are given, the minimum image dimensions containing the positions are returned: ```wl In[1]:= LinearGradientImage[{{0, 0}, {100, 100}} -> Hue] Out[1]= [image] ``` Specify a different output size: ```wl In[2]:= LinearGradientImage[{{0, 0}, {100, 100}} -> Hue, {150, 150}] Out[2]= [image] ``` --- By default, a 3D image of size $\{64,64,64\}$ is generated: ```wl In[1]:= LinearGradientImage[{{Left, Front, Bottom}, {Right, Back, Top}} -> "Rainbow"] Out[1]= [image] ``` Specify the output size: ```wl In[2]:= LinearGradientImage[{{Left, Front, Bottom}, {Right, Back, Top}} -> ColorData["Rainbow"], {40, 30, 20}] Out[2]= [image] ``` ### Options (8) #### ColorFunction (3) With no color specification, ``GrayLevel`` is the default color function: ```wl In[1]:= LinearGradientImage[{{0, 0}, {100, 100}}, {100, 100}] Out[1]= [image] ``` Specify a different color function: ```wl In[2]:= LinearGradientImage[{{0, 0}, {100, 100}}, {100, 100}, ColorFunction -> Hue] Out[2]= [image] ``` Use a built-in color gradient: ```wl In[3]:= LinearGradientImage[{{0, 0}, {100, 100}}, {100, 100}, ColorFunction -> ColorData["Rainbow"]] Out[3]= [image] ``` Use ``Blend`` to specify a color function that is a blend of multiple colors: ```wl In[4]:= LinearGradientImage[{{0, 0}, {100, 100}}, {100, 100}, ColorFunction -> (Blend[{Blue, Yellow, Green}, #]&)] Out[4]= [image] ``` --- When grayscale 3D images are produced, ``ColorFunction -> "GrayLevelOpacity"`` is used in ``Image3D`` : ```wl In[1]:= LinearGradientImage[{Left, Right}, {10, 10, 10}] Out[1]= [image] ``` --- With both ``ColorFunction`` and end point colors specified, color function is ignored: ```wl In[1]:= LinearGradientImage[{Left -> Green, Right -> Red}, ColorFunction -> GrayLevel] Out[1]= [image] ``` #### ColorFunctionScaling (2) By default, the color function parameters are rescaled between 0 and 1: ```wl In[1]:= LinearGradientImage[(Blend[{{0, Red}, {1, Yellow}}, #]&), {200, 20}] Out[1]= [image] ``` --- Scaled values might not be suitable for some color functions: ```wl In[1]:= Image[LinearGradientImage[ColorData[2], {20, 5}], ImageSize -> 100] Out[1]= [image] ``` Use ``ColorFunctionScaling -> False`` : ```wl In[2]:= Image[LinearGradientImage[ColorData[2], {20, 5}, ColorFunctionScaling -> False], ImageSize -> 100] Out[2]= [image] ``` #### DataRange (2) The default ``DataRange`` is the size of the image: ```wl In[1]:= LinearGradientImage[{{0, 0}, {50, 50}} -> Hue, {100, 100}] Out[1]= [image] ``` Specify a different data range: ```wl In[2]:= LinearGradientImage[{{0, 0}, {50, 50}} -> Hue, {100, 100}, DataRange -> {{0, 50}, {0, 50}}] Out[2]= [image] ``` --- Use a normalized data range to get the same effect, regardless of the image dimensions: ```wl In[1]:= LinearGradientImage[{{1 / 2, 1 / 2}, {1, 1}} -> Hue, {50, 50}, DataRange -> {{0, 1}, {0, 1}}] Out[1]= [image] In[2]:= LinearGradientImage[{{1 / 2, 1 / 2}, {1, 1}} -> Hue, {100, 50}, DataRange -> {{0, 1}, {0, 1}}] Out[2]= [image] ``` #### Padding (1) By default, ``"Fixed"`` padding is used: ```wl In[1]:= LinearGradientImage[{{20, 20}, {80, 80}}, {100, 100}] Out[1]= [image] ``` Use a constant padding value: ```wl In[2]:= LinearGradientImage[{{20, 20}, {80, 80}}, {100, 100}, Padding -> Red] Out[2]= [image] ``` Specify a padding scheme: ```wl In[3]:= LinearGradientImage[{{20, 20}, {80, 80}}, {100, 100}, Padding -> "Periodic"] Out[3]= [image] ``` ### Applications (2) Apply Bayer's ``4×4`` dispersed-dot dither matrix to a gradient image: ```wl In[1]:= B4 = {{8, 136, 40, 168}, {200, 72, 232, 104}, {56, 184, 24, 152}, {248, 120, 216, 88}} / 255 Out[1]= {{(8/255), (8/15), (8/51), (56/85)}, {(40/51), (24/85), (232/255), (104/255)}, {(56/255), (184/255), (8/85), (152/255)}, {(248/255), (8/17), (72/85), (88/255)}} In[2]:= i = LinearGradientImage[GrayLevel, {250, 50}] Out[2]= [image] In[3]:= Binarize[i + Image[N@PadRight[B4, {50, 250}, B4]], 1] Out[3]= [image] ``` --- Apply different gradient effects to an image: ```wl In[1]:= img = [image]; {g1, g2} = LinearGradientImage[{Bottom, {Center, 1 / 3}} -> #, ImageDimensions[img], DataRange -> {0, 1}]& /@ {"SandyTerrain", "GreenBrownTerrain"} Out[1]= {[image], [image]} In[2]:= Blend[{img, #}]& /@ {g1, g2} Out[2]= {[image], [image]} ``` ## See Also * [`RadialGradientImage`](https://reference.wolfram.com/language/ref/RadialGradientImage.en.md) * [`Blend`](https://reference.wolfram.com/language/ref/Blend.en.md) * [`ConstantImage`](https://reference.wolfram.com/language/ref/ConstantImage.en.md) * [`RandomImage`](https://reference.wolfram.com/language/ref/RandomImage.en.md) * [`Image`](https://reference.wolfram.com/language/ref/Image.en.md) * [`ColorData`](https://reference.wolfram.com/language/ref/ColorData.en.md) * [`GradientFilter`](https://reference.wolfram.com/language/ref/GradientFilter.en.md) ## Related Guides * [Creating & Importing Images](https://reference.wolfram.com/language/guide/CreatingAndImportingImages.en.md) ## History * [Introduced in 2014 (10.0)](https://reference.wolfram.com/language/guide/SummaryOfNewFeaturesIn100.en.md) \| [Updated in 2017 (11.1)](https://reference.wolfram.com/language/guide/SummaryOfNewFeaturesIn111.en.md) ▪ [2020 (12.2)](https://reference.wolfram.com/language/guide/SummaryOfNewFeaturesIn122.en.md)