1. Define the meaning of CMYK and RGB
CMYK stands for Cyan Magenta Yellow and Black. It is a term most often used in printing as these colors are mixed in the printing process to create the colors of a document.
RGB stands for Red, Green and Blue. We use 6 color printers that can use the additional information the RGB color gamut provides, so we prefer RGB images.
References : http://www.ashworthcreative.com/blog/2014/06/difference-cmyk-rgb-colors/
Differentiate the purpose of;
Channel and Colour Correction
Channel is a grayscale image the same size as the image color, made of one of the primary colors. Color digital image is made of pixels, and a pixel is made of a combination of primary colors is represented by a series of code.
Color correction is a lot easier than you think. You just need to know which. colors are complimentary (meaning on the opposite end of the color wheel) and you can use those to cancel out too much of another color. (If you need a refresher on color, check out our color guide.) You also need to be able to spot where colors are the most prominent. This means being able to tell, for example, when red is dominating the light areas of the photo and blue is dominating the dark areas. If you simple applied a blue filter to the entire photo, you’d end up with more neutral highlights—which you want—but a photo that looks too cool because the shadows are overly saturated with blue color. To recap, you need to pay attention to two major things when color correcting: which colors are dominating the photograph and which colors aren’t, and also where, tonally, those dominating colors exist.
References: http://lifehacker.com/5753621/basics-of-photoshop-color-correction-photo-retouching-and-enhancing
https://helpx.adobe.com/after-effects/using/color-correction-effects.html
Saturation and Brightness
Saturation (Chroma) — the intensity or purity of a hue
Saturation refers to how pure or intense a given hue is. 100% saturation means there’s no addition of gray to the hue. The color is completely pure. At the other extreme a hue with 0% saturation appears as a medium gray. The more saturated (closer to 100%) a color is, the more vivid or brighter it appears. Desaturated colors, on the other hand, appear duller.
Lightness (value) — the relative degree of black or white mixed with a given hue
Lightness measures the relative degree of black or white that’s been mixed with a given hue. Adding white makes the color lighter (creates tints) and adding black makes it darker (creates shades). The effect of lightness or value is relative to other values in the composition. You can make a color seem lighter by placing it next to a darker color.
The greater the difference in value between elements, the greater the contrast between them. Because of this, lightness is a good way to show contrast and indicate hierarchy among elements. About 7 steps of lightness is the maximum variation the human eye can discern.
references : http://whatis.techtarget.com/definition/hue-saturation-and-brightness
http://vanseodesign.com/web-design/hue-saturation-and-lightness/
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