HTML 5 specifies a new input type named "color" that appears like a textbox. The "color-alpha picker" above allows the user to pick the blue, red, green and alpha values and provide the color-alpha specification in a textbox. Thus, when working with transparencies/opacity there is a need to be able to refer to how the color (the one on top) and the background (the one underneath) are merged or composited together. See these transparency/opacity examples in HTML5's canvas. This information references to how the red, green and blue color information should be merged with the color that is "underneath" or "behind" the image. This terminology is most often used in graphic image editors to describe the transparency layer of an image. The reason this is called "alpha" is not because it is more simple than saying "opacity" or "transparency" (which both mean the same thing - just from a different directions), but because the generic term is from "alpha channel". Actually this is not a simple percentage of each color (i.e., the one on top and the one underneath) there is a blending algorithm that performs these partially opaque (or partially transparent). The larger the number, the less the background shows through (or the more the top layer covers up the background). If a box or text is shown with a color with an alpha value > 0 and < 1.0, it partially covers up the color of any pixels beneath. when alpha is between 0.0 and 1.0 (exclusive), the color specified by the three "rgb" value is "partially opaque" or "partially transparent".If a box or text is shown with a color with an alpha value of 0.0, it will be completely invisible (i.e., transparent) and the color of any pixels beneath show through. when alpha is 0.0, the color specified by the three "rgb" value is totally "transparent".If a box or text is shown with a color with an alpha value of 1.0, it will completely cover up the color of any pixels beneath. when alpha is 1.0, the color specified by the three "rgb" value is totally "opaque".The values for "alpha" range from 0.0 → 1.0. HTML5 adds a fourth color component called variously: "alpha", "opacity", or "transparency", This is expressed as the fourth number in the "red,green,blue,alpha" or "rgba" string. Textbox to receive the picked color from below: bb is a two digit hexademinal number 00→ff (0-255 in decimal) for blue intensityĬOLOR PART II: RGB Alpha | 32-bit color | 4 byte color.gg is a two digit hexademinal number 00→ff (0-255 in decimal) for green intensity.rr is a two digit hexademinal number 00→ff (0-255 in decimal) for red intensity.rgb(0%,0%,0%) is black (the darkest gray).rgb( a percent 0→100 for red intensity, a percent 0→100 for green intensity, a percent 0→100 for blue intensity).rgb( a number 0→255 for red intensity, a number 0→255 for green intensity, a number 0→255 for blue intensity).
HTML 4 color components were specified with four basic formats:
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