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41 lines
1 KiB
Markdown
41 lines
1 KiB
Markdown
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---
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title: images.Sigmoid
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description: Returns an image filter that changes the contrast of an image using a sigmoidal function.
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categories: []
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keywords: []
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action:
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aliases: []
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related:
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- functions/images/Filter
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- methods/resource/Filter
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returnType: images.filter
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signatures: [images.Sigmoid MIDPOINT FACTOR]
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toc: true
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---
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This is a non-linear contrast change useful for photo adjustments; it preserves highlight and shadow detail.
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The midpoint is the midpoint of contrast. It must be in the range [0, 1], typically 0.5.
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The factor indicates how much to increase or decrease the contrast, typically in the range [-10, 10] where 0 has no effect. A positive value increases contrast, while a negative value decrease contrast.
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## Usage
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Create the filter:
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```go-html-template
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{{ $filter := images.Sigmoid 0.6 -4 }}
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```
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{{% include "functions/images/_common/apply-image-filter.md" %}}
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## Example
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{{< img
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src="images/examples/zion-national-park.jpg"
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alt="Zion National Park"
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filter="Sigmoid"
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filterArgs="0.6,-4"
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example=true
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>}}
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