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Matching Local Values

The core skill of values is value comparison.

In order to create convincing values  our pictures, we need to be able to judge whether a given value in one part of the picture should lighter or darker than another, and by how much.

We also need to be able to accurately judge the values we see.

With practice, these judgements can become largely automatic. It takes time to get to that stage, or course. But it can certainly be achieved, and the most effective way to get there is to develop your skill at value comparison.

That’s just what this exercise is about.

What you need:

You need very little in the way of materials for this exercise:

  • A sheet of ordinary sketchpad paper (I use Cansons recycled sketchpads)
  • A range of graphite pencils: 2H, B and 4B will be sufficient for most values. 8 or 9B will let you go a little darker.
  • A piece of black or grey card about three inches across each side with a hole cut in the middle
  • A value to attempt to match – I’d recommend something flat, matt finish, and low chroma (near to grey) to start with.

value-comparison-1

How to do it:

Step One: Isolate the value to be matched

First, draw out a square about an inch across on a sheet of sketch pad paper. This is where we’ll draw our value swatch.

Now place the piece of card with a hole in it (we’ll call it a viewfinder) on the surface you’re going to match the value of. For this exercise, I’m trying to match the value of a sketch pad cover. I’ve chosen this because it’s almost grey – a very low chroma colour. I suggest you do the same to begin with, because high chroma colours are much harder to find the value of.

Place your sheet of paper with the square you’ve drawn so that the edge of the paper overlaps the hole in the viewfinder. Now you can compare the value you’re trying to match with the value of your paper.

value-comparison-2

Obviously, at this point, the value of the paper is much lighter than the value of the sketch pad cover.

Step Two: Estimate the value

Take the paper away from the viewfinder and lay it flat. Now take a pencil and try to fill in the square to the same value as the value you’re trying to match.

Do this carefully, don’t rush. Try to get your value square as even as possible.

For all except darker values, you’re better off using harder pencils until you find you can’t get the value dark enough. You’ll get a much smoother result this way. In the picture below, I’ve used only a 2H pencil.

Once you’ve filled the square, lay it over the viewfinder again and compare the value.

value-comparison-3

This is where the real meat of this exercise happens. This is where you start to stretch your skill at value comparison – by repeatedly comparing the value you’ve got the value you’re trying to match.

Look at your value, and decide whether it’s lighter or darker than the value you’re trying to match.

In the example above, it’s slightly lighter. So I’ll draw another square and try again:

value-comparison-4

The closer you get, the harder it is to judge. It’s the act of judging and comparing that stretches your sensitivity to value and you’re ability to correctly judge a given value.

If you find this exercise hard – that’s good, it’s supposed to be hard! With time and practice, it will get easier. Right at the beginning, when it’s the most difficult, is when you make the most improvement.

Although the value above looks fairly close, If I isolate just the two values in the photo you’ll be able to see the difference between them more clearly:

value-comparison-4b

My value is still much lighter than the one I’m trying to match. A good way to compare values more effectively is to throw your eyes out of focus or squint.

At this point I used a B pencil to darken the value a little further. Here’s attempt number three:

value-comparison-5

This is much closer. At this point I stopped. Lets look at the value comparison close up:

value-comparison-5b

Even though I thought I’d got it very close, my value is still lighter!

Another Example

Here’s another attempt, matching the value of the background of a book cover. This time the colour has a little more chroma, so it will be harder to match:

value-comparison-6

The paper is hardly any lighter than the value I’m trying to match, so just a whisper of 2H pencil should be enough to match it:

value-comparison-7

Not bad, but let’s see close up:

value-comparison-7b

It looks pretty good here, but the real test is to look at it in grey-scale (I did this in photoshop):

value-comparison-7b-bw

As you can see, this is still a shade too light. In fact, this is very common – we often tend to estimate values as too light, more often that too dark. It’s a good illustration of how even low chroma colours can make it difficult to judge value – and why this is such an important skill to practise.

Do this repeatedly with various values, gradually increasing the chroma (brightness, or intensity) of the colours you try to match. If you’ve got a way to take digital photos and make a grey-scale version of your attempts, that will be a great check to see how well you’re doing. Be prepared, it’s a harsh critic! But the feedback is excellent, and will help you improve.

This exercise may seem very divorced from what you do when you paint or draw, but actually it’s at the heart of it. By stretching this skill until it becomes automatic, you’ll naturally find yourself producing better value relationships in your work – without having to think about it. But it does take practice to get to that point.