If you already use and enjoy the editing powerhouse that is the TK series of actions panels, you probably won't learn anything new here. But, if you haven't had a look at these resources, read on.
A luminosity mask is an advanced method for selecting specific ranges of information in your image, as pixels. If you are familiar with layers and masks in Photoshop, you would have noticed that a contrast adjustment such as curves or levels will affect the entire image. If you used a luminosity mask, however, you would be able to select specific tones, colour ranges or other information, and then make adjustments in a far more targeted way. As an example, the images below will compare a simple 's' curve contrast adjustment of the overall image versus a luminosity mask of the mid tones only.
This is before any adjustments are made to show the original image...
This has been modified with a curves layer, with adjustments applied globally (to the entire image), making it a little too dark and affecting saturation.
Look at the histogram here. The selected tonal info is only a portion of the entire histogram (top right), Additionally, there is a mask now applied to the layer Using the rule of "white reveals and black conceals", a luminosity mask will vary what is affected through this masking process. Anything white (in the mask) is fully affected whilst anything black is not. Ranges in between are varying levels of opacity, hence the level of control this allows. .
What makes these masks fascinating is the broad range of applications that can be used with them. It's as simple as applying a mask to any adjustment layer or even image layers, and I often adjust clarity, selective colour editing, sharpening, Orton effects and even use luminosity selections to dodge and burn with much more control.
You may have noticed the panels along the side of my toolbar. These are the TK actions panels, which are made by Tony Kuyper. They are invaluable because making a basic series of luminosity masks is time consuming and can be quite pedantic. TK panels make it extremely easy to make targeted adjustments to a huge range of options and zones, as well as allowing quick processes of common tools and function. In addition to a variety of luminosity mask modules, he has produced the panels below which I find incredibly useful, for basic controls and mechanisms to complex actions that are simple in effect but time consuming, such as image resizing, sharpening and preparation for web use.
The control panel (left) allows fast modifications and work to occur, providing shortcuts to simple tools from all over Photoshop's menus in one spot. The actions panel is invaluable, even just for it's image preparation tool. Input your required output size, select longest edge and watch it resize, sharpen and change colour profiles to web for Facebook and other social media use.
Tony Kuyper continues to work with Sean Bagshaw, another epic photographer, to produce these panels and fantastic instructional videos. If you want to see for yourself, head over to https://tonykuyper.wordpress.com/2017/12/14/tk-basic-v6-panel-new-and-free/ and download his latest free resource, which is a streamlined version of his latest products. The bottom line is this: Luminosity masks are complex but allow incredible freedom for image editing. There are many variants of this kind of resource available but I genuinely think the TK suite is fantastic and easy to use. Tony has been very helpful with rectifying any issues and provides excellent instruction on the use of his action panels through comprehensive PDFs and videos available on his website or at Sean Bagshaw's website http://www.outdoorexposurephoto.com . Potentially one of the best purchases I have made, and I continue to upgrade as new panels are released with no hesitation.
If you're wondering why I'm spruiking TK panels so hard, it is out of genuine experience and satisfaction with the products and I recommend you take a look, and no, it isn't advertising or sponsorship.