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Dave's Luminosity Selection

Disciplines > Photography > Affinity Photo > Resources > Dave's Luminosity Selection

Download

Click here to download the latest 'Dave's Luminosity Selection' macro set.

To insert this into your library, simply click on the 3-line 'hamburger' on the top right of the library panel, click on 'Import Macros...' and point it at the downloaded file. Then click on the layer for which you want a model and click once on the appropriate macro in the 'Dave's Luminosity Selection' library group category.

Macros

Macros created include:

• Luminosity Mask (Basic): Sets four points to shape luminosity area selected, plus changes in luminosity calculation and feathering shape.

• Luminosity Mask (Easy): Does the same as the above but in a much easier way, changing middle, width and feathering of area to select.

• Luminosity Mask (Easy, Weighted): Does the same as the above, but lets you manually change the RGB weighting in the luminosity calculation.

• Mono Stretch: Creates a monochrome layer with full-range luminosity.

• Convert to Mask and Spare Channel: Converts layer to mask and also copies this to a Spare Channel.

• Convert to Selection, Mask and Spare Channel: Does the same as the previous macro, but leaves you with the area selected with marquee, in case you want to work directly with a selection.

About

Here are a number of macros that let you select areas of a photo based on their luminosity (in other words, how light or dark the pixels are). This is also called luminosity masking.

Much of photo editing is changing luminosity of different areas in order to take actions such as:

1. Make the area lighter to attract the eye.

2. Make the areas darker to move the eye elsewhere (although large dark areas will also attract the eye).

3. Create contrast with adjacent areas and so make each area more distinct and easier to separate out into parts of the image.

You can also make other adjustments to the area selected, such as blurring, changing colour, and so on.

The Luminosity Zone (Basic) macro lets you select four points (in the same way as with Blend Ranges) that represent the lower (darker) points at zero opacity (transparent) and then feathering up to full opacity (lighter, visible), then ranging to the higher full opacity point and feathering down to the fourth, zero opacity. In other words, you select a range of pixels which have a limited luminosity, and can also feather these so they blend in with adjacent areas. 

Unlike Blend Ranges, you can change the way luminosity is calculated from Red, Green and Blue. Blend Ranges uses the perceptual weighted method (30% red, 59% green, 11% blue). You can also use a simple average where all three channels have equal weighting (average). You can additionally and easily change the style of feathering, from even (linear) to exponential (sigmoid, s-curve) to cosine (s-curve). Play with these to see what works best.

The Luminosity Zone (Easy) macro does the same thing but is much easier to use, as it lets you set the Middle, Width and Feathering of the zone to select. If in doubt, use this macro.

The Luminosity Zone (Easy, Weighted) macro does the same thing as Luminosity Zone (Easy) but lets you set the weighting for R, G and B in the luminosity calculation. This is for cases when you specifically want this level of control.

The remaining three macros may be applied after the luminosity zone is selected to create masks and selection. However, while this does save memory space, it may lose your ability to go back and adjust the selected zone at a later time.

Mono Stretch is useful as a step along the way if you want selections or masks to be based on a full range (0 to 1) rather than a relative range.

Convert to Mask and Spare Channel turns the layer into a mask, shifts it to the bottom of the layer stack for future use (so you can still see your image) and also sets a Spare Channel with the values for easy loading into adjustment masks.

Convert to Mask and Spare Channel turns the layer into a mask, shifts it to the bottom of the layer stack for future use (so you can still see your image) and also sets a Spare Channel in the Channels tab, with the same values, for easy loading into adjustment masks.

Convert to Selection, Mask and Spare Channel does the same but leaves you with a selection marked with marquee ('marching ants'). This is useful if you just want to add an adjustment, which will automatically pick up the selection in its built-in mask.

Note: The macros are not 'idiot-proofed' as this would significantly increase the size of an already-big algorithm. In other words, when asked for a number 0 to 1, you can use any number you like, though the results are not defined.

Macros

Macros created include:

• Luminosity Mask (Basic): Sets four points to shape luminosity area selected, plus changes in luminosity calculation and feathering shape.

• Luminosity Mask (Easy): Does the same as the above but in a much easier way, changing middle, width and feathering of area to select.

• Luminosity Mask (Easy, Weighted): Does the same as the above, but lets you manually change the RGB weighting in the luminosity calculation.

• Mono Stretch: Creates a monochrome layer with full-range luminosity.

• Convert to Mask and Spare Channel: Converts layer to mask and also copies this to a Spare Channel.

• Convert to Selection, Mask and Spare Channel: Does the same as the previous macro, but leaves you with the area selected with marquee, in case you want to work directly with a selection.

See also

If you are having problems downloading the macros, click here to download as zip file.

Dave's Zone System

Dave's Saturation Selection