Convert an image to grayscale in HTML/CSS

Question

Is there a simple way to display a color bitmap in grayscale with just HTML/CSS? It doesn't need to be IE-compatible (and I imagine it won't be) -- if it works in FF3 and/or Sf3, that's good enough for me.

I know I can do it with both SVG and Canvas, but that seems like a lot of work right now. Is there a truly lazy person's way to do this?

Answer 1

http://snipplr.com/view/2836/grayscale-img-with-css-crossbrowser/ (via http://www.google.com/search?q=css+grayscale)?

Answer 2

It's in fact easier to do it with IE if I remember correctly using a proprietary CSS property. Try this FILTER: Gray from http://www.ssi-developer.net/css/visual-filters.shtml

The method by Ax simply makes the image transparent and has a black background behind it. I'm sure you could argue this is grayscale.

Although you didn't want to use Javascript, I think you'll have to use it. You could also use a server side language to do it.

Answer 3

Well, the FITLER attribute is specific to Internet Explorer (IE).

I am not aware, but it might exist, a CSS supported attribute in other browsers that will allow you to do this.

If anyone know's ... please let us all know.

Answer 4

Doesn't look like it's possible (yet), even with CSS3 or proprietary -webkit- or -moz- CSS properties.

However, I did find this post from last June that used SVG filters on HTML. Not available in any current browser (the demo hinted at a custom WebKit build), but very impressive as a proof of concept.

Answer 5

One terrible but workable solution: render the image using a Flash object, which then gives you all the transformations possible in Flash.

If your users are using bleeding-edge browsers and if Firefox 3.5 and Safari 4 support it (I don't know that either do/will), you could adjust the CSS color-profile attribute of the image, setting it to a grayscale ICC profile URL. But that's a lot of if's!

Answer 6

Here is a great tutorial on this very subject. http://www.ajaxblender.com/howto-convert-image-to-grayscale-using-javascript.html

Answer 7

I found the solution!!! :)

I was playing around with PHP and remembered this question (god knows why)!

I think this might be exactly what you want, I got it from the PHP GD library and added some variable to automate the process...

<?php
$img = @imagecreatefromgif("php.gif");

if ($img) $img_height = imagesy($img);
if ($img) $img_width = imagesx($img);

// Create image instances
$dest = imagecreatefromgif('php.gif');
$src = imagecreatefromgif('php.gif');

// Copy and merge - Gray = 20%
imagecopymergegray($dest, $src, 0, 0, 0, 0, $img_width, $img_height, 20);

// Output and free from memory
header('Content-Type: image/gif');
imagegif($dest);

imagedestroy($dest);
imagedestroy($src);

?>

It is not html but it might just be what you want!

Good luck!

Answer 8

If you're willing to use Javascript, then you can use a canvas to convert the image to grayscale. Since Firefox and Safari support <canvas>, it should work.

So I googled "canvas grayscale", and the first result was http://www.permadi.com/tutorial/jsCanvasGrayscale/index.html which seems to work.

Answer 9

in Internet Explorer use the filter property

in webkit and firefox there is currently no way to desatuarte an image solely with CSS. so you will need to use either canvas or SVG for a client side solution.

but i think using SVG is more elegant. check out my blog post for the SVG solution that works for both firefox and webkit: http://webdev.brillout.com/2010/10/desaturate-image-without-javascript.html

and strictly speaking since SVG is html the solution is pure html+css :-)

Answer 10

Following on from brillout.com's answer, and also Roman Nurik's answer, and relaxing somewhat the the 'no SVG' requirement, you can desaturate images in Firefox using only a single SVG file and some CSS.

Your SVG file will look like this:

<?xml version="1.0" encoding="UTF-8"?>
<svg version="1.1"
     baseProfile="full"
     xmlns="http://www.w3.org/2000/svg"&gt;
    <filter id="desaturate">
        <feColorMatrix type="matrix" values="0.3333 0.3333 0.3333 0 0
                                             0.3333 0.3333 0.3333 0 0
                                             0.3333 0.3333 0.3333 0 0
                                             0      0      0      1 0"/>
    </filter>
</svg>

Save that as resources.svg, it can be reused from now on for any image you want to change to greyscale.

In your CSS you reference the filter using the Firefox specific filter property:

.target {
    filter: url(resources.svg#desaturate);
}

Add the MS proprietary ones too if you feel like it, apply that class to any image you want to convert to greyscale (works in Firefox >3.5, IE8).