It’s not so simple- an rgb is illegal with a fourth parameter. You also need to allow for percentage decimals as well as integer values for the rgb numbers. And spaces are allowed almost anywhere. function getRgbish(c){ var i= 0, itm, M= c.replace(/ +/g, ”).match(/(rgba?)|(\d+(\.\d+)?%?)|(\.\d+)/g); if(M && M.length> 3){ while(i<3){ itm= M[++i]; if(itm.indexOf(‘%’)!= -1){ itm= … Read more
The solution by PeterVR has the disadvantage that the additional color displays on top of the entire HTML block – meaning that it also shows up on top of div content, not just on top of the background image. This is fine if your div is empty, but if it is not using a linear … Read more
This is now possible with custom properties: .brown { –rgb: 118, 76, 41; } .green { –rgb: 51, 91, 11; } a { display: block; position: relative; } div { position: absolute; bottom: 0; background-color: rgba(var(–rgb), 0.8); } a:hover div { background-color: rgba(var(–rgb), 1); } To understand how this works, see How do I apply … Read more
Bleh, this is an acknowledged issue as far as the canvas spec is concerned. It notes: Due to the lossy nature of converting to and from premultiplied alpha color values, pixels that have just been set using putImageData() might be returned to an equivalent getImageData() as different values. So this: var can = document.createElement(‘canvas’); var … Read more
Take the lowest color component, and convert that to an alpha value. Then scale the color components by subtracting the lowest, and dividing by the alpha value. Example: 152 converts to an alpha value of (255 – 152) / 255 ~ 0.404 152 scales using (152 – 152) / 0.404 = 0 177 scales using … Read more
To simulate RGBA and HSLA background in IE, you can use a gradient filter, with the same start and end color (alpha channel is the first pair in the value of HEX) background: rgba(255, 255, 255, 0.3); /* browsers */ filter: progid:DXImageTransform.Microsoft.gradient(GradientType=0,startColorstr=”#4cffffff”, endColorstr=”#4cffffff”); /* IE */
The CSS Color Module Level 4 will probably support 4 and 8-digit hexadecimal RGBA notation! Three weeks ago (18th of December 2014) the CSS Color Module Level 4 editor’s draft was submitted to the CSS W3C Working Group. Though in a state which is heavily susceptible to change, the current version of the document implies … Read more
Here’s a version that’s much simpler – not sure how performant it is. Heavily based on some django snippet I found while building RGBA -> JPG + BG support for sorl thumbnails. from PIL import Image png = Image.open(object.logo.path) png.load() # required for png.split() background = Image.new(“RGB”, png.size, (255, 255, 255)) background.paste(png, mask=png.split()[3]) # 3 … Read more