https://github.com/alladinian/histogramview

A SwiftUI view for displaying image histograms
https://github.com/alladinian/histogramview

graphics histogram image ios macos swift swiftui

Last synced: about 13 hours ago
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A SwiftUI view for displaying image histograms

• Host: GitHub
• URL: https://github.com/alladinian/histogramview
• Owner: alladinian
• Created: 2021-10-20T14:58:14.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2021-10-20T16:08:50.000Z (almost 3 years ago)
• Last Synced: 2024-09-27T08:04:13.589Z (about 13 hours ago)
• Topics: graphics, histogram, image, ios, macos, swift, swiftui
• Language: Swift
• Homepage:
• Size: 7.81 KB
• Stars: 28
• Watchers: 5
• Forks: 5
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
![HistogramView](https://user-images.githubusercontent.com/156458/138126267-b1799ab2-87fe-4e7a-86bd-e36cdd9aa6bd.png)

# HistogramView

A SwiftUI view for displaying image histograms.

## How do I use it?

It's as simple as:

``` swift

HistogramView(image: myImage)

```

*Note:* Both `UIImage` & `NSImage` are supported (by the `HistogramImage` typealias, depending on the platform).

## What options do I have for configuration?

The initializer supports channel opacity, blendMode and scale for the final graph.

``` swift

/// The opacity of each channel layer. Default is `1`

public let channelOpacity: CGFloat

/// The blend mode for the channel layers. Default is `.screen`

public let blendMode: BlendMode

/// The scale of each layer. Default is `1`

public let scale: CGFloat

```

## How fast is this thing?

Under the hood the histogram calculation is performed by `Accelerate`'s `vImageHistogramCalculation_ARGB8888` for RGB channels, so it's pretty fast actually.

Fast enough to be perfomed synchronously (although didn't test it on gigantic images).

## How is the graph curve produced?

Each channel is a `SwiftUI` `Path` that uses [Hermite interpolation](https://en.wikipedia.org/wiki/Hermite_interpolation) for generating a continous curve.

The actual implementation for the interpolator is taken from [@FlexMonkey's implementation](https://github.com/FlexMonkey/Filterpedia/blob/7a0d4a7070894eb77b9d1831f689f9d8765c12ca/Filterpedia/components/HistogramDisplay.swift#L228) (part of the [Filterpedia](https://github.com/FlexMonkey/Filterpedia) project) and adapted to be used on `Path` instead of `UIBezierPath`.

## Authors

Vasilis Akoinoglou, [email protected]