Rob Adams a Painter's Blog

February 20, 2013

Values and Keys.

Filed under: How to do,London,Painting,Thames,Uncategorized — Rob Adams @ 12:16 pm

People talk a lot about values as if they there is a correct value for light or dark in a subject. I don’t really think that there is though. Very little is said about Key or Value Scale which is I think of equal importance.
Key for those that haven’t met the idea is the range from light to dark in a painting. So a painting that has most of it’s values in the lighter range is called high keyed. Setting the key of a picture is a choice made by the artist rather like setting the exposure on a camera.
If you decide the lightest value in your picture and the darkest value then it is the relative positions of the values in your picture that matter. You can choose a narrow key in which case the lightest is pale grey and the darkest mid grey, or a wide key in which the lightest is white and the darkest black. The same picture can be painted in either key, neither is more correct or incorrect than the other. It is the relationship between tones that matters and gives coherence and believability to your picture. I have briefly I think dealt with this before but this I hope is clearer. I’m going to use a plein air of Rotherhithe which lends itself to the subject.
.
First The picture as I painted it.
Rotherhithe, Thames

At the bottom are two value scales. The bottom one the full range of possible values the top the ones actually used. Below is a diagram to show the spread of values.

Diagram

As you see the lightest possible lights and the darkest possible darks are not used in the painting. The space between the lines is the Value Range or Key. The top strip is just the area between the lines stretched to fit.

grey scale

Here is the same image in grey scale. So how would the painting look if I had used the full range? Below I have done a photoshop adjustment that gives some idea.

full range

Here it is. As you can see the picture is more contrasty and the two range strips more or less match. It still looks fine because all of the values have been stretched to fit and the relative positions are unchanged. This is rather using an elastic ruler. You are stretching the whole thing but it still has twelve divisions equally spaced. Here it is in grey scale.

grey

As you see this looks fine and probably about how I would choose to draw the scene in black and white. See that the two strips now more or less match. So what happens if we go the other way? This time we will narrow the value range rather than expanding it.

pale

It takes a moment to adjust your perception so look at the image above in isolation for a few moments. The mood has changed but the picture still works we have no difficulty in believing such a day and mood of lighting is possible. Below is the same thing in grey scale.

grey

As you can see it has rather the feel of a foggy day, but is still perfectly plausible. In fact faced with this subject you could have painted in any of the value ranges above and it would have been perfectly valid.

So remember, when you start a painting first make a decision as to the Key. Put dabs on your canvas of the lightest and the darkest you intend to use and then stick to that range of values and place your other tones between those extremes. It is your decision as the painter not necessarily set by the subject, though some subjects obviously lend themselves to a particular range. On advantage of this approach is that if, when your painting is almost done, you need to punch an area up you will have the means rather than being stuck in the position of needing a white that is whiter than white!

10 Comments »

  1. Excellent exposition that deserves a wide audience. You demonstrate this important set of ideas in an engaging way. Thanks.

    Comment by Mick Carney — February 20, 2013 @ 12:57 pm

  2. Rob, Thank you for posting this superb demonstration…I have struggled and struggled with this subject & this has given me a new understanding…going to whip out my paints & experiment with it today! I like all three versions of your painting, but like the version you painted the best.

    Comment by Maribeth — February 20, 2013 @ 1:51 pm

  3. Thanks Maribeth and Mick, It is the thing I get wrong most frequently. I get carried away and just jump in and start. But every time I stop and think it through I get a better result. It is good practice to put a dab of the brightest and darkest you intend to use then try and place a few other key tones the sky, water and the underlying tone of the right hand buildings would be the key ones in my example. When you mix them you know that the sky must be dark enough to take a good high light and the buildings not so dark as the darkest dark. Having the darkest and lightest on the board first thing allows you to judge these relationships relatively easily. Many painters end up using the full range in every picture but this rather limits the different moods you can express.
    Rob

    Comment by admin — February 20, 2013 @ 2:06 pm

  4. A fascinating analysis Rob.

    Comment by Yorky — February 20, 2013 @ 5:53 pm

  5. Superb examples ,thanks Rob, have incorporated all this into my own lessons now, really got me thinking

    Comment by tony lawman — February 20, 2013 @ 6:22 pm

  6. Thanks Tony, as you see I got back the next day, the light was even better!
    Best
    Rob

    Comment by admin — February 20, 2013 @ 6:26 pm

  7. I think it’s always easier to go lighter then darker….I find you to be a painter that makes alot sense to this dumb ass…..wannabe !! :) thanks for such great thoughts …-Sandra

    Comment by Sandra heading — February 22, 2013 @ 11:22 am

  8. Hi Sandra, thanks for reading my meanderings! I find it easiest to start light in watercolour and drawing but not, I am discovering, in oils especially if painting a la prima since it is easier to lighten than darken due to the way the paint overlays. The best policy in all media is of course to go in with the final tone you want first time! But for mere mortals this is unlikely to happen. We do judge dark tones poorly. It is I think because we are always trying to spot things that might eat us hidden in the shadows. The result is that the brain records shadows in vision as lighter than they are. So if you paint them as you perceive them then a viewer does the same thing again and they end up too light, having been lightened twice once by the artist then again by the viewer.If you go darker than you think it ought to be then the viewer will “see” into the shadows and the final result should convince more. We actually can physically differentiate more tones at the dark end of the tone spectrum than the light. We also pick up on them more so that detail in the shadow areas can be distracting and often needs radical simplification.
    Best
    Rob

    Comment by admin — February 22, 2013 @ 12:05 pm

  9. Rob, your last comment is very helpful (as is the thread and indeed your entire blog!). Painting in watercolors, I am afraid to go too dark, and so my paintings often have a washed-out quality that probably reflects a too-narrow value scale. You’ve given me some new ways to look at this, thanks!

    Comment by Dewayne Matthews — February 22, 2013 @ 6:31 pm

  10. Hi Dewayne, Watercolour does present special problems in this area. Making an area dark with repeated glazes is very tricky and takes a light touch to stop the whole lot going muddy. So it pays dividends to get the tones as right as possible first go. If I am heeding my own advice I premix my main washes to the strength they need by doing several tiny thumbnails/notans. Once these are dry I can be confident of how dark they will dry and that they are right relative to each other. Only for the really key tones maybe 3 or 4. I usually then split the mixes into two and add a little warm to one and blue to another to allow variation by dipping randomly between them. When you dip your brush in to these mixes make sure to squeeze the brush dry before dipping or they will get diluted. The aim is to have no large areas that have been washed over more than twice and preferably most of the painting only once. It should look too dark as it goes on!
    Best
    Rob

    Comment by admin — February 22, 2013 @ 6:45 pm

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