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社区首页 >问答首页 >HTML5画布对比度滤镜

问HTML5画布对比度滤镜
EN

Stack Overflow用户
提问于 2012-06-21 03:09:49
回答 3查看 5.2K关注 0票数 2

如何使用HTML5画布像素处理功能调整图像的对比度？我已经成功地很容易地改变了图像的亮度，但对比度似乎更复杂一点。

有没有人知道我可以遵循的算法，或者我可以借鉴的javascript代码样本？

提前感谢您在这个问题上的帮助。

javascript
html
canvas
filter
contrast
EN

回答 3

Stack Overflow用户

回答已采纳

发布于 2012-06-21 03:14:21

既然你说你已经调整了亮度，听起来你所需要的就是调整对比度的算法这里是一个C#方法的线程(请看更新2)，代码的逻辑是健全的，并且可以在任何程序中工作：

Adjust the contrast of an image in C# efficiently - Stack Overflow

票数 3
EN

Stack Overflow用户

发布于 2017-03-27 17:11:31

我会张贴演示，其中所有的过滤器。您可以很容易地在canvas上通过id或class使用它。但问题是你不能用画布渲染这意味着你不能保存或预览。因为画布不能渲染风格。

代码

代码语言：javascript
复制
<!-- canvas -->
<html>
<head>
<style>
img {
    width: 33%;
    height: auto;
    float: left;
}
.origional {filter:none;}
.blur {-webkit-filter: blur(4px);filter: blur(4px);}
.brightness {-webkit-filter: brightness(0.30);filter: brightness(0.30);}
.contrast {-webkit-filter: contrast(180%);filter: contrast(180%);}
.grayscale {-webkit-filter: grayscale(100%);filter: grayscale(100%);}
.huerotate {-webkit-filter: hue-rotate(180deg);filter: hue-rotate(180deg);}
.invert {-webkit-filter: invert(100%);filter: invert(100%);}
.opacity {-webkit-filter: opacity(50%);filter: opacity(50%);}
.saturate {-webkit-filter: saturate(7); filter: saturate(7);}
.sepia {-webkit-filter: sepia(100%);filter: sepia(100%);}
.shadow {-webkit-filter: drop-shadow(8px 8px 10px green);filter: drop-shadow(8px 8px 10px green);}
</style>
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js" type="text/javascript"></script>
<script>
$( document ).ready(function() {
//origional canvas image
    var canvas = document.getElementById("canvas");
    var ctx = canvas.getContext("2d");
    var img = document.getElementById("origional");
   ctx.drawImage(img, 0, 0,300,300);

   $('#button').click(function() {
    canvas.classList.add("origional");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});

   $('#button1').click(function() {
    canvas.classList.add("blur");
    canvas.classList.remove("origional");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});

   $('#button2').click(function() {
    canvas.classList.add("brightness");
    canvas.classList.remove("blur");
    canvas.classList.remove("origional");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button3').click(function() {
    canvas.classList.add("contrast");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("origional");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button4').click(function() {
    canvas.classList.add("grayscale");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("origional");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button5').click(function() {
    canvas.classList.add("huerotate");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("origional");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button6').click(function() {
    canvas.classList.add("invert");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("origional");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button7').click(function() {
    canvas.classList.add("opacity");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("origional");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button8').click(function() {
    canvas.classList.add("saturate");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("origional");
    canvas.classList.remove("sepia");
    canvas.classList.remove("shadow");
});
   $('#button9').click(function() {
    canvas.classList.add("sapia");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("origional");
    canvas.classList.remove("shadow");
});
   $('#button10').click(function() {
    canvas.classList.add("shadow");
    canvas.classList.remove("blur");
    canvas.classList.remove("brightness");
    canvas.classList.remove("contrast");
    canvas.classList.remove("grayscale");
    canvas.classList.remove("huerotate");
    canvas.classList.remove("invert");
    canvas.classList.remove("opacity");
    canvas.classList.remove("saturate");
    canvas.classList.remove("sepia");
    canvas.classList.remove("origional");
});
});
</script>
</head>
<body>
<h1>
canvas
</h1>
<canvas id="canvas" width="300" height="300" ></canvas>
<br>
<div ><input type="button" id="button" value="origional" />
<input type="button" id="button1" value="blur" />
<input type="button" id="button2" value="brightness" /> 
<input type="button" id="button3" value="contrast" /> 
<input type="button" id="button4" value="grayscale" /> 
<input type="button" id="button5" value="huerotate" /> 
<input type="button" id="button6" value="invert" /> 
<input type="button" id="button7" value="opacity" /> 
<input type="button" id="button8" value="saturate" /> 
<input type="button" id="button9" value="sepia" /> 
<input type="button" id="button10" value="shadow" />  
</div>
<br>
<!-- image -->
<h1>
image
</h1>
<img id="origional" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img id="blur" class="blur" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="brightness" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="contrast" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="grayscale" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="huerotate" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="invert" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="opacity" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="saturate" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="sepia" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
<img class="shadow" src="https://lh5.googleusercontent.com/-bSF6HLBpWZU/AAAAAAAAAAI/AAAAAAAAABI/6UVYOKY6QhE/photo.jpg" alt="Pineapple" width="300" height="300">
</body>
</html>

这里是Live Demo

票数 1
EN

Stack Overflow用户

发布于 2012-06-21 03:12:48

Pixastic提供了大量出色的效果，您可以使用示例Editor来查看其中的一些功能。Pixastic brightness/contrast example

这是我制作的一个对比鲜明的马里奥的演示。

另外，如果您不想使用整个库，请查看pixastic github source code for the contrast method，了解如何在代码中实现它。

票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/11126503

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