How to select by colour with Colour Range
Select every red, every highlight or every skin tone at once with Colour Range in Paint by Zaweba, using eyedroppers, presets and fuzziness.
Clicking with a magic wand selects one patch of colour. Colour Range selects that colour everywhere in the picture, in one go, with soft edges where the match fades. That difference matters for jobs like changing the colour of a dress that is broken up by folds and shadows, or toning down every bright highlight in a landscape photo at once.
In Paint by Zaweba you open it from Select > Colour Range. It works on the colours of your image and gives you a selection you can use with any adjustment, mask or filter in the app.
Picking the colour
There are three eyedroppers. Pick sets the colour to match by clicking on the image. Add takes in another shade, which you will need for most real objects since a red car is many reds, from deep shadow to glinting highlight. Subtract removes a shade that has crept in by mistake, such as the red of a brick wall behind the car.
Fuzziness decides how far a pixel's colour can be from your picks and still be selected, partly or fully. Low fuzziness keeps the selection tight and hard; high fuzziness takes in near neighbours with a soft fall-off. Drag it while watching the preview rather than typing numbers.
Invert flips the result, which is handy when it is easier to pick the background than the subject.
Presets for common jobs
Rather than picking, you can choose a preset. There are the colour families (reds, yellows, greens, cyans, blues, magentas), the tonal ranges (highlights, midtones, shadows) and skin tones. The tonal presets are a quick way to make a selection for brightening shadows or calming highlights, while skin tones gives a starting point for retouching faces and hands without touching clothes or backgrounds as much.
Two more options go further. The Out of gamut preset selects colours that fall outside what the print colour space can show, which is useful before preparing a picture for printing. Localised colour clusters keeps the match to areas near the places you picked, so a red jumper can be chosen without also selecting a red sign on the other side of the frame.
Previewing the selection
Colour Range can show its selection in greyscale, against black, against white, or as a Quick Mask overlay. Greyscale is the most honest view: white is fully selected, black is not, and grey is partly selected. Black and white backgrounds show the selected pixels in their real colours, which helps when you are judging whether a pale or dark fringe is included. Quick Mask keeps the photo visible with a tinted overlay on what is left out.
Putting the selection to work
Once you press OK you have a normal selection. The usual next step is to limit an adjustment to it, for example by using the selection as the mask of a Hue/Saturation adjustment layer to shift the colour of the dress. Because the mask is soft wherever fuzziness made the selection partial, the change blends smoothly into the folds and shadows.
You can also save the selection to a channel through the Select menu so you can load it again later, or take it into Quick Mask to paint out the parts that should not be there.
Common Colour Range errors
Picking one pixel and pushing fuzziness up to catch the rest is the classic error. It drags in unrelated colours. Instead, use Add on a few shades across the object and keep fuzziness moderate.
Another is forgetting that Colour Range matches colour, not objects. If the background contains the same colour as your subject, it will be selected too. Use Localised colour clusters, or tidy the extra areas with a lasso afterwards.
Finally, check the selection in greyscale before you commit. Grey areas you didn't expect are partly selected, and an adjustment will affect them partly too. It's better to see that now than after you've graded the whole picture.
A typical use
Say you want a blue car to be green. Open Colour Range, Pick on the body, Add on the shadowed door and a highlight on the bonnet, Subtract the sky if it creeps in, and set fuzziness so the greyscale view shows the car clean against a dark background. Press OK, add a Hue/Saturation adjustment masked by the selection, and shift the hue. The edges and reflections follow, because the selection followed the colour.
