No, taking away blue does not add yellow

This is another of those concepts I keep seeing presented in videos.  Videos by respected and knowledgeable photographers and re-touchers, who otherwise demonstrate a complete and thorough understanding of the concepts they are explaining.   For some reason though, they often have a blind spot when it comes to this one. It’s one of those where for most images it probably doesn’t matter too much if you don’t understand what is truly happening  however it makes my eyes twitch (in a sort of Herbert Lom in the Pink Panther sort of way) whenever I hear this being said, so here’s my $0.5 worth on the subject 🙂

It concerns making adjustments to colour in an image usually using the curves adjustment tool (but is true of any tool that changes the brightness levels of individual colour channels).   I’m going to demonstrate using curves.  The claim, is that by lowering the contribution of one colour channel you increase the contribution of the opposite colour channel.  The curves tool in Photoshop allows for adjustment of the Red, Green and Blue (RGB) channels separately and for all three together  (for an overall adjustment in brightness).   This leads to questions about adjusting other colours such as Yellow.    Red, Green and Blue are the opposites of Cyan, Magenta and Yellow:   RGB is the opposite of CMY, and C, M and Y are made from mixing R, G and B.   This is all good, however every explanation I’ve seen online then goes off the rails.   Let’s take Yellow as the target colour channel you need to increase.  There is no Yellow colour channel in the curves tool (or levels etc).  All the tutorials I’ve watched on colour tell you to do this by reducing blue.  This will not work, and here’s why:-

Here’s the test bed we’ll be using to explore this:  I have a black background (so no brightness at all in either red, green or blue).  We have a Yellow patch, a white one and a blue one.   I’m going to use a curves adjustment to increase or decrease the contribution of each colour channel and in this control image you can see it’s completely linear in all channels  (and so having no effect).

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Project Noir part II

_OHL4540-WebsiteThis time we concentrated on one shot – a backlit interior concept with volumetric light (i.e. light given volume by some medium – in this case, an even fog).  Caspar reprised his previous outfit, now complete with a nice black Fedora.   I found some 20 year-old Gauloise Caporal white cigarettes when we moved house last year that really looked the part in a soft blue case.    We also had a crystal decanter, glass, and the airgun we used on the last shoot. All of these went onto a nice period desk from another room in the old manor house.

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Project Noir–Part One

_OHL5770-WebsiteSomeone once said something like “Cinematographers kick photographers’ asses, all day long”.  I can’t remember who this was, and the Intarweb doesn’t seem to know either.  However, even though these are two different art forms, I do find that things some photographers seem to think of as new and exciting developments , are not news to DP’s and movie lighting directors who’ve been creating mood and drama with light for decades.

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Headshots

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From a session for stage and screen actor, Stacey Lynne Crowe.   Actor’s headshots need to be pretty simple, and must show what they really look like – so no editing allowed.   I process these in Lightroom and they have contrast and exposure adjustments made to lift the shadows, knock the highlights down just a bit and then I set the white and black points.  On the skin I reduce contrast a bit , and put a tenth of a top into the eyes.  Then sharpen the eyes, lips, and nose and I’m done. 

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Chocolates

_DSC4494-Edit-WebsiteJust playing around with the scrim I made a while back. It’s roughly 1.5x2m with a frame made from 21mm plastic waste pipe (B&Q sell this along with all the corners, T pieces, 45 degree corners etc. to make any kind of frame you want).  The surface is Translum plastic which is made by Savage.  You can buy it on a roll 1.5m wide.  The idea is to project light onto the scrim so that it drops to nothing before it reaches the edge of the scrim – and so there’s no edge visible.  You can also try projecting patterns using something like the Lightblaster however on this occasion I just wanted a classic ball of light with a nice gradual drop-off towards the edges.

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Books wot I Like

 

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Books.   They’re still a good idea if you ask me, even in this age of YouTube learning (which I also love).  Especially for learning something visual like say.. photography:  I like to have a physical, printed book.    In this post, I’m going to present some of my favourite photography related books, and why I like ‘em.

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