Introduction

Advancing knowledge in Photoshop can sometimes seem like a daunting task; especially if you are new to the program. What I recommend to newbies’ is to learn things in Photoshop which are relevant to the craft. If you are never going to be making posters’ and adding text and colourful graphics, skip learning that, at least to begin with. Targeted learning is the best way forward. Learn what you need to know. This brings me to this tutorial. To use this tutorial, you must understand the basics of layers and painted masks in Photoshop. This knowledge can easily be learned if not known, by using youtube or by experimenting. Stack up some layers of the same photograph in Photoshop and add white or black masks, then paint through with white or black brushes and see what occurs. If you understand this concept, you are ready for this tutorial. It will take time to understand Luminosity Masking, so please go easy on yourself initially. This is a concept that will absolutely further your control of the editing process and is the most modern method to blending exposures.

There are so many times in the editing process that we require to blend exposures because our camera sensor cannot see the same range of light that our eyes can. The traditional way to do this in the past is to use graduated filters, for example, to darken the sky and bring the exposure into line with the foreground. Many photographers’ still use this method and it works well with subjects such as seascape photography. It can also be satisfying to see a very close to finished result on the back of the camera LCD screen. However, there are such times, when mountains, trees or other subjects stick up into the skyline and using a graduated filter will blacken or burn these areas, giving an un natural result. If we consider other genres, such as astro landscape photography, where it is common practice to capture a sky exposure, and blend it to a longer foreground exposure, it goes without saying that graduated filters are not going to be of much use to anyone. Therefore, it is best that we consider Luminosity Masking as an excellent way of doing these things.

Bracketing

Luminosity literally means ‘brightness’. Therefore a Luminosity Mask is a mask based on brightness. What makes this technique so curious, is that we can craft a Luminosity mask for different brightness values, to target different areas within the photograph we are editing. Not only that, this means that we can make advanced selections and replace those areas - for example, replace the sky with the proper exposure, rather than having burnt out or blown highlights. This principal requires at shooting that the photographer captures the full range of the light on the scene to begin with. Without doing this, we will be unable to blend the exposures for a natural result. Luminosity selections can, as I alluded to earlier, be used with astrophotography also. We can make a very smooth, advanced selection of the land, (for example, including the fine detail in tree branches within that selection) and replace it with the longer exposure version, making a cleaner, ‘brighter’ landscape below the dark starry skies above. (This technique is a little more advanced, so it is best we start with blending just two exposures.) I regularly will use 2-3 exposures to capture the full dynamic range at the scene. I usually prefer, for most cases during the day, shooting a base exposure, and one -2EV below this, and one +2EV. The best way to think about this process is the base exposure is the best exposure you could make on it’s own, not too bright, not too dark, a ‘Goldilocks’ exposure if you will.

Lumi32

In this tutorial I am going to use Lumi32 from Jimmy McIntyre in order to carry out the exposure blending. This in my opinion, is the best 32 bit luminosity masking program available and can construct more detailed masks than the 16 bit luminosity masking programs available. That said, Jimmy also offers Raya Pro, a full suite which includes the excellent Instamask which can also construct luminosity masks for us.

The Base Exposure

Here is a base exposure which has overexposed highlights and underexposed shadow areas. We are going to exposure blend this image with luminosity masks to balance the detail across the entire dynamic range. Note the other exposure I have included for the sky highlights, and the exposure to properly expose the landscape. The first thing we need to do is import all three into Photoshop as smart object layers. We need to place them in a logical order for blending together:

• Base Exposure at bottom of stack

• Sky Exposure above this

• Exposure for the shadows and dark tones / Landscape at the top of the stack

Preparing for Exposure Blending

Before we start the selection and blending process, we need to do a couple of things before we begin. We need to clean off any chromatic aberration from each of the files, remove vignettes and balance the exposures relative to one another. The reason we need to do this is because chromatic aberration will leave halos at the intersections of the masks we make. Vignettes can interfere with our selection - the darker corners can prevent our mask going ‘white’ and this won’t allow us to make a definitive selection. Lastly, we need to balance exposures relative to one another so that the finished blend appears natural, (more on this later).

I have now removed CA and used lens corrections to cull the vignette on each of the three exposures.

Next we have to examine each of the exposures within Camera Raw and make some decisions about bringing the exposures into some parity with each other, so that they can be effectively blended.

This page is being continually developed and expanded. Check back soon. Last updated 5th August 2024.