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docs/content/en/functions/images/index.md

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+---
+title: Image Functions
+description: The images namespace provides a list of filters and other image related functions.
+godocref:
+date: 2017-02-01
+categories: [functions]
+aliases: [/functions/imageconfig/]
+menu:
+  docs:
+    parent: "functions"
+keywords: [images]
+toc: true
+---
+
+
+## Image Filters
+
+See [images.Filter](#filter) for how to apply these filters to an image.
+
+### Brightness
+
+{{% funcsig %}}
+images.Brightness PERCENTAGE
+{{% /funcsig %}}
+
+Brightness creates a filter that changes the brightness of an image.
+The percentage parameter must be in range (-100, 100).
+
+### ColorBalance
+
+{{% funcsig %}}
+images.ColorBalance PERCENTAGERED PERCENTAGEGREEN PERCENTAGEBLUE
+{{% /funcsig %}}
+
+ColorBalance creates a filter that changes the color balance of an image.
+The percentage parameters for each color channel (red, green, blue) must be in range (-100, 500).
+
+### Colorize
+
+{{% funcsig %}}
+images.Colorize HUE SATURATION PERCENTAGE
+{{% /funcsig %}}
+
+Colorize creates a filter that produces a colorized version of an image.
+The hue parameter is the angle on the color wheel, typically in range (0, 360).
+The saturation parameter must be in range (0, 100).
+The percentage parameter specifies the strength of the effect, it must be in range (0, 100).
+
+### Contrast
+
+{{% funcsig %}}
+images.Contrast PERCENTAGE
+{{% /funcsig %}}
+
+Contrast creates a filter that changes the contrast of an image.
+The percentage parameter must be in range (-100, 100).
+
+### Gamma
+
+{{% funcsig %}}
+images.Gamma GAMMA
+{{% /funcsig %}}
+
+Gamma creates a filter that performs a gamma correction on an image.
+The gamma parameter must be positive. Gamma = 1 gives the original image.
+Gamma less than 1 darkens the image and gamma greater than 1 lightens it.
+
+### GaussianBlur
+
+{{% funcsig %}}
+images.GaussianBlur SIGMA
+{{% /funcsig %}}
+
+GaussianBlur creates a filter that applies a gaussian blur to an image.
+
+### Grayscale
+
+{{% funcsig %}}
+images.Grayscale
+{{% /funcsig %}}
+
+Grayscale creates a filter that produces a grayscale version of an image.
+
+### Hue
+
+{{% funcsig %}}
+images.Hue SHIFT
+{{% /funcsig %}}
+
+Hue creates a filter that rotates the hue of an image.
+The hue angle shift is typically in range -180 to 180.
+
+### Invert
+
+{{% funcsig %}}
+images.Invert
+{{% /funcsig %}}
+
+Invert creates a filter that negates the colors of an image.
+
+### Pixelate
+
+{{% funcsig %}}
+images.Pixelate SIZE
+{{% /funcsig %}}
+
+Pixelate creates a filter that applies a pixelation effect to an image.
+
+### Saturation
+
+{{% funcsig %}}
+images.Saturation PERCENTAGE
+{{% /funcsig %}}
+
+Saturation creates a filter that changes the saturation of an image.
+
+### Sepia
+
+{{% funcsig %}}
+images.Sepia PERCENTAGE
+{{% /funcsig %}}
+
+Sepia creates a filter that produces a sepia-toned version of an image.
+
+### Sigmoid
+
+{{% funcsig %}}
+images.Sigmoid MIDPOINT FACTOR
+{{% /funcsig %}}
+
+Sigmoid creates a filter that changes the contrast of an image using a sigmoidal function and returns the adjusted image.
+It's a non-linear contrast change useful for photo adjustments as it preserves highlight and shadow detail.
+
+### UnsharpMask
+
+{{% funcsig %}}
+images.UnsharpMask SIGMA AMOUNT THRESHOLD
+{{% /funcsig %}}
+
+UnsharpMask creates a filter that sharpens an image.
+The sigma parameter is used in a gaussian function and affects the radius of effect.
+Sigma must be positive. Sharpen radius roughly equals 3 * sigma.
+The amount parameter controls how much darker and how much lighter the edge borders become. Typically between 0.5 and 1.5.
+The threshold parameter controls the minimum brightness change that will be sharpened. Typically between 0 and 0.05.
+
+## Other Functions
+
+### Filter
+
+{{% funcsig %}}
+IMAGE | images.Filter FILTERS...
+{{% /funcsig %}}
+
+Can be used to apply a set of filters to an image:
+
+```go-html-template
+{{ $img := $img | images.Filter (images.GaussianBlur 6) (images.Pixelate 8) }}
+```
+
+Also see the [Filter Method](/content-management/image-processing/#filter).
+
+### ImageConfig
+
+Parses the image and returns the height, width, and color model.
+
+{{% funcsig %}}
+images.ImageConfig PATH
+{{% /funcsig %}}
+
+```go-html-template
+{{ with (imageConfig "favicon.ico") }}
+favicon.ico: {{.Width}} x {{.Height}}
+{{ end }}
+```