Lightroom Mask Brush Question

I'm using Lightroom 5.

I sometimes use the mask brush to 'whiten' the background of a high key type studio shot, I'm sure in the past I didn't have to be that accurate near the edges as it sort of 'recognised' a bit that was white rather than the subject. In fact I distinctly remember that if I hovered the crosshair in the middle of the brush over a 'white' bit and clicked the mask would only be applied to the bit of the brush that was the same colour, generally leaving the subject as it was.

It no longer does this though.

Have I imagined this? Or have I just changed a setting or something? I'm not even sure what I could Google to find the answer so thought I would try here!

Thanks in advance

check "auto mask" box.

Yep towards the bottom of the Mask panel is a check box.

In case you didn't know you also have an A brush a B brush and an Erase brush. The A & B brushes can be set up with different settings so that you just switch between brushes to select the different settings (mask on, mask off).

Thanks, I'll give that a go, it was driving me insane!

Hitting the A key will toggle it on and off too. This can make it easy to switch without realising.

As a side note, due to the way that the brush choses the colour that is selected sometimes you can get a spattered effect as you paint if the subject has a lot of texture. In this case it is often better to go over the egde of what you want selecting. Then you can use the erase brush with the auto mask to erase beck to the edge.

Alan

BigAl007 wrote in post #17014731
As a side note, due to the way that the brush choses the colour that is selected sometimes you can get a spattered effect as you paint if the subject has a lot of texture. In this case it is often better to go over the egde of what you want selecting. Then you can use the erase brush with the auto mask to erase beck to the edge.

Big + 1 to this. It is a very useful tip.

Also, just in case you aren't au fait with the keyboard controls yet, pressing/holding the ALT key will switch the brush from Paint to Erase. Very handing when trying to make detailed adjustments and needing to switch back and forth.

Lastly, if you are having trouble getting a good edge it can often be very helpful to adjust the Feather and Flow of the brush. The reduced strength and opacity of the brush means that you can create a gentler transition and it doesn't matter as much if you go over the edge.

Thanks. Yea, I must have pressed A accidentally.

BigAl007 wrote in post #17014731
Hitting the A key will toggle it on and off too. This can make it easy to switch without realising.

As a side note, due to the way that the brush choses the colour that is selected sometimes you can get a spattered effect as you paint if the subject has a lot of texture. In this case it is often better to go over the egde of what you want selecting. Then you can use the erase brush with the auto mask to erase beck to the edge.

Alan

Another vote for this method.

Brushing on, don't try to be super accurate.
Brushing off, use Auto Mask and get as accurate as you can.

Auto Mask when applying the mask will very often leave a splotchy pattern which is almost invariably undesirable.