Switch colours pain­lessly

James Pater­son shows how to grips with this use­ful Pho­to­shop mode and learn how to take com­plete con­trol of colour in your work­flow

NPhoto - - CONTENTS -

Make ac­cu­rate colour swaps with Pho­to­shop CC’S LAB mode

LAB Color mode might sound like some­thing that re­quires a white coat and a clip­board, but it isn’t just for dig­i­tal imag­ing boffins, it’s for any­one who wants to shift, boost and take con­trol of the colour in their pho­tos. In this tu­to­rial, we’ll ex­plain how it works.

First, a lit­tle about colour modes. Most of the time we view and work on im­ages in the RGB colour mode. This stands for Red, Green and Blue, and from com­bi­na­tions of these three colours any other colour can be made. When in RGB mode each pixel has a spe­cific R, G and B value be­tween 0 and 255. This de­ter­mines not just the colour in­ten­sity but also the bright­ness of the pixel. For ex­am­ple, if a pixel has R 255, G 255, B 255 then it is fully white. So in RGB mode the colour and bright­ness of any given pixel are bound, mak­ing it dif­fi­cult to change one in­de­pen­dently of the other.

LAB Color works dif­fer­ently. When we switch to LAB each pixel is again des­ig­nated three val­ues, just like RGB. But in­stead of three colour val­ues, there are two – the A and B chan­nels. The third chan­nel – L – is ded­i­cated to lu­mi­nance. Put them all to­gether and we get L-A-B.

Un­like RGB the LAB val­ues are based on how the eye sees colour, not how a de­vice cal­cu­lates it, and it brings some im­por­tant ben­e­fits. It means we can al­ter colours in­de­pen­dently of bright­ness, like with the car here. We can also boost colour sat­u­ra­tion and con­vert to mono­chrome. Here’s how…

The LAB val­ues are based on how the eye sees colour, not how a de­vice cal­cu­lates it, and it brings some im­por­tant ben­e­fits

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.