LESSON 18 · COLOUR

Every colour your screen can show is described by three numbers, and Photoshop's colour picker is a map of all of them. This lesson decodes that map so you can choose colour on purpose instead of clicking around until something looks right. It also nails down the rule that runs through the whole module: value does the work, colour does the mood.

SOFTWARE

Finish first: L14, L17

• The five-value scale file you built in L14
• Photoshop open, tablet connected and pressure working
• Window > Color and Window > Swatches panels visible

WATCH

Proko — Ties the three colour properties directly to the digital picker you are about to use.

Marco Bucci — Ten minutes that explain why value carries a picture before colour ever gets a vote.

THE LESSON

Click the foreground swatch at the bottom of the toolbar and the Color Picker opens: one big square, one vertical rainbow strip, and a stack of number fields. Ignore RGB and CMYK for now. The three fields that matter to a painter are H, S and B. Photoshop labels the third one B for Brightness; most art books call the same idea Value. Between them, those three dials reach every colour the screen can produce.

Hue (H) runs 0 to 360 degrees around a colour wheel. Roughly: 0 is red, 60 yellow, 120 green, 180 cyan, 240 blue, 300 magenta, and 360 arrives back at red. Saturation (S) runs 0 to 100 — at 0 the colour is a pure neutral grey, at 100 it is as intense as the screen can manage. Brightness (B) runs 0 to 100, from black up to the brightest version of that hue. Learn the numbers properly. The moment you can look at a colour and say 'that's about H30, S40, B70' out loud, you have stopped guessing and started mixing.

In the Color Picker the tall rainbow strip sets hue. The big square then shows every saturation and brightness available for that one hue: left to right is saturation, bottom to top is brightness. The top-left corner is white, the entire bottom edge is black, and the top-right corner is the pure, undiluted hue. Once you see the square as a map rather than a mystery, picking becomes navigation.

That changes how you move. A short move across the map gives you a colour related to the one you had, which is what you want most of the time. A long jump gives you a colour that will not belong with anything else in the painting. Open Window > Color, then use the panel menu to switch it to HSB Sliders so the three numbers stay on screen while you paint. And use Alt-click (Option-click on a Mac) with any brush selected — it borrows the eyedropper for a second and samples the colour under the cursor without changing tools.

Everything from Module 4 still applies. A painting survives or fails on its value structure, and colour is what you lay on top of a structure that already works. There is a fast way to check this in Photoshop: put a Black & White adjustment layer at the very top of your layer stack (Layer > New Adjustment Layer > Black & White) and toggle its eye icon on and off. If the picture falls apart when the colour disappears, no amount of colour choice will rescue it. Go back and fix the values.

There is a trap hiding in the B number. Brightness is not the same thing as the value your eye perceives. Pure yellow at H60 S100 B100 and pure blue at H240 S100 B100 both read B100, but desaturate them and the yellow lands as a pale grey while the blue lands as a dark one. Yellows are always lighter than the number suggests; blues and violets are always darker. Trust the Black & White check, not the field.

Your screen can produce colours more intense than any tube of paint, and that is exactly the problem. If every shape in the picture sits at S90, nothing stands out, and the whole thing gets that buzzing, plastic look that says 'made by someone new to digital'. Treat saturation as a limited budget. Spend the top of the range on the focal point and a few small accents; let most of the picture live between S15 and S50.

Greys count as colours too. A grey carrying a slight hue — say H210 S8 B55 — feels like part of the painting. A grey at S0 is a hole in it. When you pick a colour and it looks somehow wrong, try dragging saturation down fifteen points before you change anything else. It fixes the problem more often than any other single adjustment.

Traditional mixing means pulling two pigments together on a palette. Digital mixing means sampling and nudging. Alt-click a colour already on the canvas, move a short distance across the picker toward where you want to go, and paint. A useful discipline while you are learning: change no more than two of the three numbers at a time. Move hue and saturation but hold brightness, or move brightness alone. Changing all three at once is how you lose track of what you did.

One habit to break before it forms: do not shade a colour by dragging straight down the brightness axis, and never by mixing in black. That produces the chalky, dusty look you see in beginner work everywhere. Real shadows shift hue as well as value, and the next few lessons are about exactly why.

PRACTICE · 30 MIN

1. Open the L18 worksheet file. The top row already holds the five greys from your L14 value scale.
2. In the empty row underneath, fill the first square with any colour you like at any saturation.
3. Turn on the Black & White adjustment layer at the top of the stack and compare that square to the grey directly above it.
4. Turn the adjustment off and change only the B number until the two squares read as the same grey when you turn it back on. Ignore hue and saturation while you do this.
5. Repeat for the other four squares, using a different hue in each one. Make at least one of them a yellow and one a blue.
6. Write the final H, S and B numbers underneath each square with the Type tool.
7. Save as L18-value-match.psd.

Done when: All five colour squares vanish into their matching greys when the Black & White layer is switched on — you cannot tell which row is which. Note how far the B number for your yellow ended up from the B number for your blue.

Download these and work along with the lesson.

CHECK YOURSELF

Answer out loud first, then open each one to compare.