Mask for "highlighter" effect

[TitlesGuy]

Hi, I'm new to Affinity, and need some help understanding what I'm seeing. I copied an object from InDesign and pasted it into Publisher, and it gives exactly the effect I need, but can someone explain how it works?

 this is a solid yellow 12-pt line (curve) over a placed B&W graphic. It appears to overprint the image. It is not "transparent" (It has 100% opacity), but is somehow blended with the underlying image.

When I disassemble the line (pasted from InDesign), it reveals what appears to be a yellow-stroked curve grouped with a large mask.

 How does this work, and how could I recreate it?

[Hangman]

Hi @TitlesGuy and welcome to the forums,

You may find you don't need the Mask layer but basically with the yellow line selected have a play with the Blend Modes in the Layers Panel...

 

[Alfred]

As @Hangman has demonstrated, if you position a yellow shape on top of a B&W graphic and set the blend mode for the shape layer to ‘Multiply’, the black areas of the graphic will show through. The colour values are literally multiplied together and then adjusted to be within the allowable range, so black (value zero) always prevails. If you were to use a colour graphic instead of B&W you’d see different colours, but anything lighter than yellow would remain unchanged.

[TitlesGuy]

Cool! Thanks, Hangman.

One of the first things I tried was the blend settings under Layer Effects: Color Overlay, but that didn't do anything useful. Never would have thought to look at the Opacity dropdown. Couldn't be easier.

[Hangman]

Hi @TitlesGuy,

The Opacity slider may not be the best option because that will decrease the intensity of your yellow 'bar'. Selecting the Multiply Blend Mode will maintain the intensity of your yellow 'bar' while at the same time revealing the music notes beneath as the two layers are 'multiplied'...

[TitlesGuy]

3 minutes ago, Hangman said:

The Opacity slider may not be the best option because that will decrease the intensity of your yellow 'bar'. Selecting the Multiply Blend Mode will maintain the intensity of your yellow 'bar' while at the same time revealing the music notes beneath as the two layers are 'multiplied'...

I understand. I referred to the "Opacity dropdown" because the untitled "Blend" dropdown is right next to the opacity slider, so they seemed to be all part of "Opacity". I'm well aware that I don't want to change opacity. 

[Alfred]

5 minutes ago, TitlesGuy said:

the untitled "Blend" dropdown

That's a good point. The 'Blend' dropdown doesn't even display a tooltip when you hover over it, at least not on Windows.

[Hangman]

3 minutes ago, Alfred said:

That's a good point. The 'Blend' dropdown doesn't even display a tooltip when you hover over it, at least not on Windows.

It's the same on Mac, there are numerous options where no tooltip is displayed so I completely understand the confusion for new users...