| Matching a transparent color to a solid
Need a method |
CSS_Kidd
msg:4055983 | 4:35 pm on Jan 7, 2010 (gmt 0) |
I hope I can explain this right. I have a solid blue background color on a web page. Then I have a 800px solid white centered container that is going to hold all my content. What I want to do is have transparent blue div that while over the white, will be as close to the solid blue page background as I can get it. Right now I am just eyeballing it. And I would like to know if there is an actual method to figuring this out. I have searched everywhere with no answers. This is as close as I can get it.
solid blue background = #99ccff
transparent blue over solid white = Opacity 37%, #0099FF NOTE:
There is no CSS alpha/trans applied. The trans blue is a transparent png image created in illustrator set to 72ppi in RGB color mode (as basic as it gets). If anyone has a method other than just "eying it", please let me know
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limbo
msg:4059262 | 6:58 pm on Jan 12, 2010 (gmt 0) |
Screengrab the image - open in image editor and 'pipette' the colour?
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CSS_Kidd
msg:4059273 | 7:24 pm on Jan 12, 2010 (gmt 0) |
Well that makes more sense... Match the solid to the merged color that the transparent over white produces! You know what is stupid I did that for a site I did a while back. I guess I was just so dead set and concentrating so much on matching the solid (websafe) color, that I forgot it was much easier to do the reverse.
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birdbrain
msg:4100613 | 7:33 pm on Mar 18, 2010 (gmt 0) |
Hi there CSS_Kidd,
you may find this example of interest.
There is an arithmetical method to calculate the background-color value of the div with opacity
applied, so that it matches the body background-color value.
The arithmetic needs to be applied to both the opacity div and the container div to obtain
the correct result.
The body background-color is #99ccff or rgb(153,204,255).
The container background-color is #ffffff or rgb(255,255,255).
We cannot use your opacity value of 0.37 in this case as it would produce a negative r value.
The minimum value would be 0.4.
Here is the arithmetic....
- body - rgb(153,204,255)
- container - rgb(255,255,255)
- opacity:0.4
- r value=(r*0.4)+(255*0.6)=153, which gives r=0
- g value=(g*0.4)+(255*0.6)=204, which gives g=127
- b value=(b*0.4)+(255*0.6)=255, which gives b=255
- opacity div - rgb(0,127,255) or #007fff
Here is the example..
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="language" content="english">
<meta http-equiv="Content-Style-Type" content="text/css">
<title></title>
<style type="text/css">
body {
background-color:rgb(153,204,255); /* #99ccff */
}
#container {
width:760px;
padding:60px 0;
margin:auto;
background-color:rgb(255,255,255); /* #ffffff */
}
#div1 {
padding:10px;
background-color:rgb(0,127,255); /* #007fff */
opacity:0.4;
}
</style>
<!--[if IE 6]>
<style type="text/css">
#div1 {
filter:alpha(opacity=40);
zoom:1;
}
</style>
<![endif]-->
</head>
<body>
<div id="container">
<div id="div1">opacity 0.4</div>
</div>
</body>
</html>
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birdbrain
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