Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/cmahnke/hdr-canvas


https://github.com/cmahnke/hdr-canvas

Last synced: 3 months ago
JSON representation

Awesome Lists containing this project

README 

        
# `hdr-canvas`



This module contains a collection of functions and classes to work with the HDR support for HTML `canvas` elements in chromium based (like Chrome, Edge, Opera and Brave) browsers.



**This should only be considered as proof of concept or alpha code, don't use it in production environments!**



**Even if the display of HDR images works, the HDR support for the `canvas` element needs the browser flag `enable-experimental-web-platform-features` to be enabled. For example, open chrome://flags#enable-experimental-web-platform-features in Chrome to activate it.**



**Especially operations on the `ImageData` arrays are not optimized, e.g. quite slow.**



# Feature detection



Import the required function(s):



```javascript

import { checkHDR, checkHDRCanvas } from "hdr-canvas";

```



## Examples `checkHDRCanvas()`



The functions return `true` if HDR is supported, example:



```javascript

const canvas = document.getElementById("canvas");

if (checkHDRCanvas()) {

  canvas.configureHighDynamicRange({ mode: "extended" });

} else {

  console.debug("hdr not supported");

  return;

}

```



This can be useful to add a warning (using the [`fillText()`](https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/fillText) method) to the canvas if it doesn't support HDR content.



## Example `checkHDRCanvas()`



```javascript

if (checkHDRCanvas()) {

  hdrCanvas.innerText = "HDR Canvas are supported";

  hdrCanvas.style.color = "green";

} else {

  hdrCanvas.innerText = "HDR Canvas are not supported";

  hdrCanvas.style.color = "red";

}

```



# Canvas



**Note: Currently the Chrome flag `enable-experimental-web-platform-features` needs to be enabled to have HDR support for the `canvas` element. You need to tell your visitors about that.**



The HDR `canvas` support is activated by initializing a canvas context using the following snippet:



```javascript

const colorSpace = "rec2100-hlg";

canvas.configureHighDynamicRange({ mode: "extended" });

const ctx = canvas.getContext("2d", {

  colorSpace: colorSpace,

  pixelFormat: "float16",

});

```



## Canvas setup



The snippet above is also available as function:



```javascript

import { initHDRCanvas } from "hdr-canvas";

```



## Implicit Canvas setup



It's now also possible to use a HDR enabled Canvas by wrapping the browser internal `getContext()` function, by calling `defaultGetContextHDR()`.



```

import {defaultGetContextHDR, checkHDR, checkHDRCanvas} from 'hdr-canvas';



if (checkHDR() && checkHDRCanvas()) {

  defaultGetContextHDR();

  console.log('Enabled HDR Canvas');

}

```



**Note:** This example wraps the call to `defaultGetContextHDR()` into a check (`checkHDR() && checkHDRCanvas()`), because calling the function in a browser that isn't HDR-capable will break every subsequent call to `getContext()`.



## Resetting default HDR canvas



Use the method `resetGetContext()` to undo the changes by `defaultGetContextHDR()`.



```

import {resetGetContext} from 'hdr-canvas';



resetGetContext();

```



## Importing `Uint16Image`



Afterwards one can use [ImageData](https://developer.mozilla.org/en-US/docs/Web/API/ImageData) with a `float16` array, first the `Uint16Image` needs to be imported:



```javascript

import { Uint16Image } from "hdr-canvas";

```



## Example: Loading an image



This example assumes `image` to be a [HTMLImageElement](https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement) including an existing image.



```javascript

const offscreen = new OffscreenCanvas(image.width, image.height);

const loadCtx = offscreen.getContext("2d");

loadCtx.drawImage(image, 0, 0);

const imData = loadCtx.getImageData(0, 0, image.width, image.height);

console.log(imData);



var hdrCanvas = document.createElement("canvas");

hdrCanvas.width = image.width;

hdrCanvas.height = image.height;



const rec210hglImage = Uint16Image.fromImageData(imData);



const ctx = initHDRCanvas(hdrCanvas);

ctx.putImageData(rec210hglImage.getImageData(), 0, 0);

```



# Three.js WebGPU



**Note**: Make sure to have Three.js added as a dependency.



This is just a drop-in-replacement for the regular `WebGPURenderer` of Three.js.



```javascript

import HDRWebGPURenderer from "hdr-canvas/three/HDRWebGPURenderer.js";

```



**Note:** Starting Three.js 167 the WebGPU renderer is the new default renderer. This has several consequences for the required imports. Use this import instead of the official one and if your using Vite _don't_ provide an import map of resolver alias configuration.



```

import * as THREE from 'three/src/Three.js';

```



Use it as you'll do with a `WebGPURenderer`.



```javascript

renderer = new HDRWebGPURenderer({ canvas: canvas, antialias: true });

```



## Updating textures



Starting from Three.js version 167 you need to fix imported UHDR Textures, otherwise they will appear black:



```

model = gltf.scene;

model.traverse((element) => {

  if (element?.material?.type != undefined) {

    let targetMaterial = new THREE.MeshBasicMaterial();

    THREE.MeshBasicMaterial.prototype.copy.call(targetMaterial, element.material);

    element.material = targetMaterial;

  }

});

scene.add(model);

```



## Compatibility



This currently doesn't work with Firefox, due to missing support for HDR and only partial WebGPU support.

One can import `WebGPU` and use also a HDR check to guard from errors:



```

import WebGPU from 'hdr-canvas/three/WebGPU.js';

```



Only use the provided renderer if the browser supports WebGPU and HDR:



```

if (WebGPU.isAvailable() && checkHDRCanvas()) {

  renderer = new HDRWebGPURenderer({canvas: canvas, antialias: true});

} else {

  renderer = new THREE.WebGLRenderer({canvas: canvas, antialias: true});

}

```



# Examples



All examples requires a Chromium based browser (like Chrome, Edge, Opera and Brave) and a HDR-enable monitor.



- [Contrast enhancement for UV images using HDR](https://christianmahnke.de/en/post/hdr-image-analysis/)

- [HDR IIIF](https://christianmahnke.de/en/post/hdr-iiif/)

- [Ultraviolet Photogrammetry](https://christianmahnke.de/en/post/uv-photogrammetry/)



---



# TODO



The following things might be improved:



- Try to detect change of screen for HDR detection

- Improve speed

  - Provide WebWorker

- Documentation

  - Link to browser HDR support

  - Document `Uint16Image`