How to make dramatically smaller layered files

Luminosity masks and general layer masks are incredible tools for creating beautiful images and using non-destructive workflows. But like any tool, they can also be over-used. That can lead to unnecessarily large TIF files and some limits to your flexibility to make changes later. There are a number of situations where other approaches can yield the same or similar results as layer/luminosity masks, and give you other benefits when they are suitable.

Specifically, I’m referring to using BlendIf instead of luminosity masks, vector masks instead of simple layer masks, and combining group masks to eliminate extra masks. This can save substantial file space, allow you to save and re-open files more quickly, and enable more flexible workflows for non-destructive editing.

Lumenzia includes built-in tools to not only help you get the most from you luminosity masks, but also use alternatives when they are suitable. In this tutorial, you’ll learn about several of them in depth.

When to use BlendIf instead of luminosity masks

BlendIf is effectively a form of luminosity masking. It is quite limited in comparison to luminosity masks in general, but it can do a very good job of replicating generic light and dark masks, as well as midtones (to a lesser degree). This applies when you would directly apply a luminosity mask to an image, not when painting through a selection to create the mask (which offers substantial local control that BlendIf cannot come close to replicating). So this means that BlendIf is almost never a good alternative for exposure blending, but there are several other luminosity masking uses that it can replace quite well.

Color grading, protected vignettes, and more basic dodging and burning are all good candidates for using BlendIf. You can frequently get results which are just as good, but with some added benefits: smaller files and a more non-destructive workflow. While luminosity masks are grayscale images which can increase the size of your file by as much as 33%, BlendIf has absolutely no impact on the file size. Zero. That means less disk space used, faster saves, and faster re-opening of the image later. And the non-destructive benefits are also very useful. Whereas a luminosity mask does not adapt to future changes, BlendIf does. So if you use BlendIf to target highlights for color grading, you could later retouch the underlying image without having to worry about updating a layer mask.

Using BlendIf with Lumenzia is simple, but here are a few tips to get the most out of it:

  • Use BlendIf from the start where possible. Trying to convert a luminosity mask to a BlendIf later likely will require some other tweaks to maintain the same look. It’s much easier to do it once.
  • The fastest way to use BlendIf with Lumenzia is to <shift>-click the mask you wish to use, such as “L” or “L2”. Once you have created it, use the blue sliders in Lumenzia to customize (if the sliders are grey, you probably have an active layer mask on the layer, just deselect the mask or delete it so that the sliders are blue, which indicates that the BlendIf is the target for the sliders).
  • You can also create more advanced BlendIf by switching Lumenzia to the If:under or If:this modes via the dropdown at top-left. The “under” mode is the best choice most of the time (and is the only one you should use when working on an adjustment layer).
    • You can target color by clicking the swatches at the top to target the red, green, and blue channels (the others are combinations: yellow is really red and green).
    • The “not” BlendIf masks can be incredibly helpful for targeting color. Remember that targeting a color channel is not the same thing as targeting color. The highlights of the red channel include red, purple, yellow, and white. If you want to just target red colors, you should actually use “not L” green and “not L” blue (because red colors do not have significant amounts of green or blue). You could then target red highlights if you want to limit your reds to the brightest rests.

Do not use BlendIf for exposure blending, anytime you need to paint through a selection (most dodging and burning), when you need to customize the mask for precision, or any other time BlendIf yields inferior results. In general, you should be using luminosity selections to create luminosity masks for nearly all advanced work, and BlendIf is not a good substitute for any local work like that.

When to combine luminosity masks

Group masks (putting a masked layer into a group with its own separate mask) are a great way to help non-destructively reveal only portions of a luminosity mask without altering the luminosity mask in a permanent way. They are extremely useful for getting the perfect mask. Sometimes you need to keep them to be able to make refinements later, and sometimes you know you won’t need that capability any longer. If you don’t, then the extra mask is just consuming disk space unnecessarily. Lumenzia’s “Combine” button allows you to easily combine the grouped luminosity masks to save space.

To use it, just make the group layer active and click “Combine”. Lumenzia will do all the work for you and create a result which is identical. This will work even if you have several layers inside the group, which will save you additional file space. This is also a helpful tool to better understand how the grouped mask really affects the image, as you will now be able to see the exact mask being used.

Do not use “combine” when you will likely need to revise the group mask later. The flexibility is well worth the extra file size when needed.

When to use a vector mask instead of a layer mask

Unlike BlendIf, vector masks do not support any luminosity targeting. They should never be used to replace luminosity masks. But they are excellent replacements for simple masks created from lasso or marquee selections. This includes such masks which are subsequently feathered. Just like BlendIf, vector masks take up absolutely no space and can therefore save substantial space compared to a layer mask. If you are saving an uncompressed file, these potential gains are just as great. If you are saving compressed files, these simple layer masks do compress much better and the savings won’t be as great – but there is still much to be gained.

In addition to saving space, vector masks are paths which can be easily revised in ways that layer masks cannot. So if you are comfortable with paths, the pen tool, or direct selection tool – you can easily make non-destructive changes to vector masks.

Vector masks can also reduce clutter, as you can place both a vector mask and layer mask on the same layer. So instead of needing a group mask, you may be able to do everything on one layer (with a layer mask or BlendIf to target by luminosity and a vector mask to localize to a general area of the image).

Vector mask support is built into Lumenzia and here are a few tips to get the most out of it:

  • Anytime you are creating a mask from a lasso/marquee selection or using a vignette, consider creating a vector mask. These are all excellent times to use them.
  • When you use any of the buttons to create a mask in in Lumenzia (such as “Mask” or “Vignette”) and have an active selection or path, Lumenzia will ask if you would like to create a layer mask or vector mask. Just choose vector. If you previously choose layer and to remember that choice permanently, you can instead <shift>-click Mask to see all the options again or go to the menu (three bars icon at top-right) and reset popup notifications to be prompted again.
  • Lumenzia will feather vector masks by default. You can always change this later via the slider in Lumenzia. Make sure the vector mask is targeted (has white corners around it), as the slider will target a layer mask or BlendIf if they are on the same layer and the vector mask is not active.
  • To refine a vector mask’s shape, use Photoshop’s “direct selection” tool. This is the white arrow, which you can activate by clicking <shift>-<A> to toggle between the selection tools. **
  • Never try to create a vector mask from an active luminosity selection. This will not create useful results and can take a while to process while Lumenzia tries to make sense of the complexity of the luminosity selection.

Do not use vector masks instead of luminosity masks or when you need custom brushing, this is just a replacement for simple lasso/marquee selections.

** Note: Photoshop treats feathering of layer masks and vector masks fundamentally differently at the edges of the image. As a result, a feathered vector mask (unlike the otherwise identical layer mask) will cease to affect the edges, which would create problems for vignetting (as the edges would suddenly get light again instead of showing the expected result). The fix is to move edge points further outside the image canvas, and Lumenzia will do this for you AUTOMATICALLY when you create a vignette. There is nothing you need to do, but in case you wish to revise your vignette vector mask (path) later, you should just be aware that this is done on purpose to ensure a proper vignette so that you can refine it properly. The reason for this is that vector masks can extend beyond the edges of the visible image, while layer masks cannot – so Photoshop treats them differently at the edges.


Making smaller layer masks in compressed files

While I did not demonstrate this in the video above, there is yet another way to save on file size. When you save your image as a compressed TIF (or PSD / PSB, which are compressed by default), the amount of detail in the layer mask matters. So painting a solid black or white color on unused portions of the mask will help your image compress to a smaller size. This is a great option when you might be tempted to use “Combine”, but still want to retain some flexibility. In this case, you just remove areas of detail you would definitely not use (rather than removing everything you aren’t using right now).

There are a couple of quick and easy ways to do this:

  • In Lumenzia, just draw a rough lasso selection around the area you would like to keep, make your masked layer active, click the * button at the top of the panel, and then click “Mask”. The * button will intersect the selection and mask, which means it will only keep what’s inside the lasso selection. It is best to not feather the selection here when asked.
  • Alternatively, you can just manually brush on the layer mask. Be sure to paint all the way to black or white. Leaving a very dark or very bright area with detail will still consume a lot of space. I would recommend using the first method with Lumenzia for simplicity and guaranteed results.
Greg Benz Photography