Understanding The Difference Between Flow And Opacity In Photoshop

On this video tutorial Aaron Nace from Phlearn looks at two settings of the brush tool – flow and opacity in Adobe Photoshop.

Following the beautifully made (but rather long) intro at 2:12, Nace looks at two aspects of the very popular brush tool – the flow and opacity. To understand this think of a this:

Flow – allows you to build up ink over and over again as you move your courser over the area (think of a pen on paper going over the same area and filling it with more and more color in every pass).
Opacity – opacity is more of a computer generated way of painting. Let’s say that you painted a canvas with 50% Opacity, you will never get more than 50% coverage unless you stop clicking your mouse (or digital pen) and click again on the same area.

Both methods are good in some situations and not necessary good in others. Generally flow is the more natural way of painting but in some cases opacity will be useful. Opacity transitions (where you put another layer on top of an existing one) doesn’t look very natural and it tend do be pretty sharp – sometimes this can be good – in most cases – not really.

Flow doesn’t show you that hard edges so adding more and more color is more natural looking. A nice shortcrust when you are using the brush tool: shift 1 to 0 controls the flow while 1 to 0 controls the opacity.

Notice that you can use flow and opacity together – so if you set your opacity to 50% – you can use the flow to build up your brush strokes – but you will be limited to 50% (unless you stop and start again like we talked about before).

From around 9:00 Nace shows some examples of actually using this with dodge and burn and layer masks.

You can find many more Photoshop video tutorials on LensVid’s Photoshop section (and you can find a lot more Phlearn videos on our special Phlearn subsection).

Iddo Genuth

Iddo Genuth is the founder and chief editor of LensVid.com. He has been a technology reporter working for international publications since the late 1990's and covering photography since 2009. Iddo is also a co-founder of a production company specializing in commercial food and product visual content.