Exposure Blending with TK8: Two methods

Exposure blending is an editing technique to better control global contrast in high dynamic range scenes where either the shadows or highlights might be clipped. Specific parts from multiple exposures are combined to insure that there is no (or significantly less) clipping in the final image. Exposure blending recovers shadow and highlight detail. While there are a number of algorithms and apps available to create HDR blends, the consensus seems to be that the results don’t always look natural. Shadows might be excessively light, global contrast looks to be off, and there may be halos around high-contrast edges.

Manually blending exposures using luminosity masks generally overcomes these problems. Luminosity masks focus on specific tones in the image and then seamlessly blend or taper into other tones. This is an ideal characteristic for exposure blending. However, using them for this purpose is usually not as easy as simply applying a luminosity mask to one of the exposures. Additional modifications to the masks, the exposures, or the manner in which the mask is applied to the image are often needed.

I don’t do a lot of exposure blending with my images, but from what I’ve done and have seen others do, there appears to be three main goals:

  1. Recover clipped highlights and shadows. This is essentially a working definition of exposure blending. A high dynamic range scene where the sensor is unable to capture either the brightest or darkest elements needs to use at least two exposures blended together to display the full dynamic range of the scene.
  2. Eliminate or reduce noise in the shadows. Sometimes the sensor can capture a scene’s full dynamic range, but the shadows are quite noisy. Blending in a separate shadows exposure that has the shadow values shifted to the right on the histogram provides both more detail in the shadows and less noise.
  3. Create realistic contrast in the blended image. This would include local contrast in each exposure that is blended as well as global contrast in the blended image.

One thing to NOT do with exposure blending is to try and finish the image based solely on the blending process. The goal should be to make a blended exposure that is a good starting point for additional development in Photoshop. In fact, it probably makes sense to aim for a less-finished blended image as there are lot of useful development techniques that might not be available during the blending process.

Method #1: Match exposures

For many landscape images, exposure-matching is a convenient blending method. It makes creating a perfect blending mask (the luminosity mask) nearly foolproof. This is the method demonstrated by Dave Kelly in the video below. The important step in this method is making the light and dark exposures to be blended look pretty much the same in Lightroom or Camera Raw. This often involves increasing the Exposure of the dark image and decreasing the Exposure of the light image. Additional adjustments to Highlights, Shadows, Blacks, Whites, and Contrast can then be incorporated to make the dark and light images appear similar. Clipped values will not be recoverable, of course, but much of the rest of the image can be adjusted to have similar brightness and contrast. The matching is especially important in the transition zone, where the dark and light exposures “meet.” A good exposure match in the transition zone means that there will be no blending halos in areas of strong contrast (like along the horizon or the edges of buildings).

When using matched exposures for blending, it’s very easy to create a mask that works to facilitate a perfect blend since the images already look quite similar. However, it’s still important to modify the mask to make sure it brings through the best-exposed pixels from both the light and dark exposure. For example, dark values should come from the light exposure in order to decrease shadow noise in the blended image. Mask modification usually involves creating some pure black and pure white areas via a Curves or Levels adjustment of the mask or painting black or white directly on the mask. It’s just the transition zone that needs to have various shades of gray in the mask in order to blend together pixels from both exposures.

NOTE: If using smart objects of the RAW files for blending, after the blending mask has been created, consider revisiting the RAW files by double-clicking the smart object thumbnails and creating better tone, color, and/or contrast in the areas revealed by that exposure. Just remember to try and maintain the exposure match in the transition zone.

Method #2: Paint through luminosity selections

While exposure-matching tends to work well for landscape images with separate sky and foreground areas that have an obvious transition zone, more complex subjects or more complex lighting situations might require a different approach. In the video below, Emil von Maltitz uses various luminosity masks generated with the TK8 plugin to create selections that then serve as stencils for painted masks. The painted masks reveal various image elements from different exposure layers. In Emil’s example, four different exposures are used, and very little work is done on the RAW files before exporting them to Photoshop for blending. It’s the mask-painting through luminosity selections that creates the blend.

The TK8 plugin makes it easy to find the right mask, but the real key for making mask-painting work, I think, is to use a lower-opacity brush (Emil uses 20 to 40 percent opacity) and then judiciously choosing where to paint on the image to bring through the desired exposure. Multiple brush strokes with lower-opacity brushes allow the effect to be slowly built up as each brushstroke adds additional paint to the layer mask. Using more than two exposures for blending adds to the complexity of the blending process, and Emil uses groups for helping to keep the Layers panel organized. Painting through luminosity selections also requires keeping track of what parts of each exposure layer will be useful in the final blend. Emil obviously has a good sense for this, though it would likely take some practice to be proficient when using more than two exposures.

SUMMARY: Exposure-matching and mask-painting are two methods for manually exposure blending high dynamic range scenes in Photoshop. Both methods employ luminosity masks to achieve a seamless blend. Exposure-matching has the advantage of creating an excellent transition zone so that critical areas, like horizon lines, have no halos in the blended image. Mask-painting allows for using original exposure information and is ideal for bringing out details and textures in the blended image.

PERSONAL NOTE: When working with high dynamic range scenes, I almost always start by applying a linear profile to the RAW image and then clicking the “Auto” button in Lightroom or Camera Raw. This process is the best way to see what’s actually recoverable in any given exposure. The linear profile does a fantastic job of recovering highlight details. And, since it has lower contrast in the dark areas than the Adobe profiles, it often shows better detail in the shadows as well. High-contrast shadows with Adobe profiles can look nearly black. Using a linear profile plus “Auto” helps to see what’s really there.

Linear Profile Follow-Up, Triple Play Actions, Luminosity Mask Workflow

Linear Profile Follow-Up

First off, I want to offer a sincere “thank you” to everyone who has contributed RAW images to help expand the linear profile repository.  There are now free linear profiles for nearly 170 cameras available on this site, and I hope to keep adding more.  I also appreciate the feedback from photographers who have experimented with the linear profiles on their images.  Many have let me know they’ve had good results.  That’s not surprising.  Linear profiles provide additional flexibility and often an improved RAW file conversion. Once installed, it’s super easy to try the linear profile during any RAW conversion in Lightroom or Camera Raw to see if it makes a difference. I hope you’ll try working with a linear profile on a few images and see what you think. Also, if your camera isn’t listed on the repository page, please contact me to get it added.

Here are a few of other things worth mentioning about linear profiles. 

  • You won’t apply a linear profile using the Camera Raw filter inside Photoshop.  I show how to install the linear profile using Photoshop’s Camera Raw filter in the installation PDF, but installation and application are two different things.  The linear profile can only be applied to a RAW file during the conversion process.  That means using Lightroom or Camera Raw (not the same as the Camera Raw filter).  Some people have written that they can’t see their installed linear profile.  That’s likely because they are trying to use it on an image in Photoshop via the Camera Raw filter.  That’s not going to work.  A RAW file is the only image the linear profile can be applied to.  So make sure you’re working with a RAW file in Lightroom or Camera Raw when you want to apply the linear profile in your workflow. You can then open the converted image in Photoshop to finish processing it.
  • If you already have a dedicated color-matching workflow, I’m not advocating discarding it in favor of using a linear profile.  There are people who have indicated they’ve found ways to combine color-matching with linear profiles (and several more who have asked about it), but this is not an area where I have any expertise.  I use linear profiles simply because they help enhance creativity in my workflow.  I go with what looks right when it comes to image color and am relatively unconcerned if my choice is correct relative to the original subject.  So, if you already have a workflow that properly matches output color to your satisfaction, I’d stick with it until someone publishes additional information on how to incorporate linear profiles into the color-matching process.
  • No linear profiles for “monochrome” cameras. RAW files from monochrome cameras, like some Leica models, can’t be imported into the Adobe DNG Profile Editor that’s used to create the linear profile.  So I’m not able to profile these monochrome-only cameras.
  • Linear profiles for cameras where the sensor has been converted for infrared photography are questionable.  In fact, I’m not sure if linear profiles are even possible with these converted cameras or if they’d be as effective as linear profiles for color images.  Page 8 of the documentation for the Adobe DNG Editor instructions discusses infrared-modified cameras if anyone wants to experiment with this.

Triple Play Actions

Dave Kelly has a good video on using the Lights and Darks Triple Play found in TK Actions menu of the TK7 Combo and Cx modules.  The Triple Play can help improve brightness, contrast, and detail in the image.  It creates a set of layers on the Layers panel in Photoshop, and users then turn on the visibility of different layers to achieve the desired effect.  My favorite way to use these actions is using the Darks Triple Play to enhance image details, and Dave demonstrates how to do this.  The Lights Triple play is best used for enhancing brightness and contrast in the highlights.  Both actions are easy to use once you understand what they do.  Watch Dave’s video and I think you’ll be ready to give both a try.

Luminosity Mask Workflow

In a second video linked below, Dave presents a simple Photoshop workflow involving luminosity masks.  Lights, Darks, Midtone, and Zone masks are used along with the “mask-the-mask” technique to isolate the adjustments to specific parts of the image.  One thing that comes through in this video is that luminosity masks aren’t restricted to making just brightness and contrast adjustments in the image.  Dave also uses them for making Hue/Saturation adjustments, and this demonstrates the flexibility of these masks.  Basically, once you’ve found the right mask to target what you want to adjust in the image, you can use whichever adjustment works best to accomplish your goal.  Regardless of the type of adjustment, the self-feathering nature of luminosity masks insures all adjustments through these masks blend smoothly into the image.

Be sure to subscribe to Dave Kelly’s YouTube channel to be notified when he posts new content.

The Linear Profile: A new beginning in Lightroom and Camera Raw

Several months ago I switched to using a linear profile as my starting point for RAW file conversions in Camera Raw. It’s been an interesting journey. The linear profile seems to have made Camera Raw more responsive to my edits. Linear profiles work in Lightroom (Lr) the same way as in Camera Raw (Cr). I’ve shared the technique with a few other photographers. The response is usually positive. While some don’t find them all that different than the standard Adobe Raw profiles (like Adobe Standard, Adobe Color, or Adobe Landscape), others have described the experience of using linear profiles as “not fighting the sliders anymore” and “the sliders seem better calibrated.” Using a linear profile offers a subtle shift in the RAW file conversion process that’s helping me take my images further in Lr/Cr before switching over to Photoshop. Yes, I still use luminosity masks and other techniques in Photoshop, but I’m starting with a better conversion and so have less to do to finish the image. The discussion below is partly from the linear profile repository page on my website where there are free downloads of linear profiles for various cameras. The Lr/Cr-ready profiles available there will make it easy for photographers explore the use of linear profiles and determine their potential as a creative tool.

What is a linear profile?

The linear profile is simply a set of instructions that tells Lightroom, Adobe Camera Raw, or other RAW processing software how to display the data from a RAW file captured by a digital camera. The conventional profile is non-linear (not a straight line), as shown by the red curve in the attached figure. This bowed profile was selected long ago for practical reasons. Curves with this general shape convert the dull, flat output from a digital camera to a brighter displayed image that more closely resembles how we see things. The red curve in this figure is the Adobe Standard profile. Its shape is typical of commonly used profiles. Note how the red tone curve brightens essentially all pixel values while increasing shadow contrast (steeper curve) and decreasing highlight contrast (less steep curve). The resultant displayed image looks “familiar” with good brightness and contrast. Since the profile is the initial interpretation of the camera RAW data, there are valid reasons to choose one that brings the image to an “attractive” point where the adjustments in Lr/Cr can be used to refine the final result. However, a profile does NOT have to be curved. A linear (straight-line) profile, as shown by the black line in the figure, could also be used. If the profile used by the program is linear, the displayed image is typically less vibrant, but (and this is important) it also better represents the actual data in the RAW file. If the conventional profile is considered step one in the processing workflow, then the linear profile is “step zero.” The linear profile allows ALL pixel adjustments to be made entirely by the photographer, whereas, with a curved (nonlinear) profile, the first major step in developing the image is already shaped by the software and camera engineers who designed that profile. The linear profile takes a step back to offer a new level of control for interpreting digital camera data and opens new opportunities in the process

How to use a linear profile

1. Click “Auto” after applying the linear profile. Installing and using linear profiles is described in this PDF. In terms of using them, my current strategy is a combination of “Auto” and manual. When the linear profile is first applied to the image, it looks darker, less saturated, and has less contrast. This is disappointing, but entirely expected. Remember, the standard Adobe Raw profiles are designed to make the image look good, so removing them and reverting to a linear profile makes the image look not-so-good anymore. However, there is an easy fix to get back a reasonably good starting point. Just click the “Auto” button in Lr/Cr. Adobe’s algorithm for the “Auto” button has gotten pretty good, and even the darker, flatter image that results from applying the linear profile is much improved after clicking it. Using “Auto” with a linear profile frequently gives better results than using it with an Adobe Raw profile. The image below shows the difference between using “Auto” with a linear profile and the Adobe Color profile. With the linear profile (on the right), the highlights are full of texture and detail, and the shadows are not overly contrasty. The Auto-processed linear profile also has richer color and better global contrast. In this case, the linear profile clearly provides a better starting point for additional adjustments. Every image is different, of course, but a linear profile combined with “Auto” is generally a good place to begin.

2. Adjust Exposure and Contrast and other sliders. After clicking “Auto,” an Exposure and Contrast adjustment will almost certainly still be necessary, but don’t stop with those adjustments. The real beauty of using a linear profile is how much more responsive the sliders in Lr/Cr are now compared to starting with one of the Adobe Raw profiles. The various adjustments perform as expected without “breaking” the image, and the sliders often have some additional leeway before reaching their extreme positions where no additional adjustments are possible. Shadows, Highlights, Whites, Blacks, Vibrance, and Saturation can all be useful in fine-tuning the image.

NOTE: An alternate approach is to skip the “Auto” adjustment and start working directly with the Lr/Cr sliders. It’s entirely possible to outperform the “Auto” algorithm, especially once you gain confidence in the way the image responds to the various sliders when starting with a linear profile.

3. Fine-tune color. Adjusting color balance is one of the things that I find especially easy to do with the linear profile. This usually involves just small adjustments with the Vibrance and Saturation sliders in the Basic tab after clicking “Auto”, but I also always visit the Color Mixer in Camera Raw (HSL/Color in Lightroom), since these sliders now work exceptionally well to control hue, saturation, and luminance of the various colors.

Advantages of linear profiles

  • More flexibility in Lr/Cr since the sliders often provide additional room for adjustments.
  • More predictable adjustments in Lr/Cr since the image responds better to slider movements.
  • Better shadow and highlight recovery.
  • Richer, but not over-saturated, colors to work with.
  • Hue, saturation, and luminance adjustments work better.
  • More pleasing RAW conversions.
  • “Expose-to-the-right” has greater potential since applying a linear profile darkens the image.

Linear profiles are camera-specific

Each camera model requires a different linear profile. Once installed, Camera Raw/Lightroom will only display a linear profile option if there is an installed linear profile that matches the camera from which the RAW file was originally produced. Linear profiles for a variety of different camera models can be downloaded at the bottom of the linear profile repository page. If your camera is not listed, contact me to make to have it added to the repository.

Summary

I’m continuing to learn about and experiment with the linear profile for my camera. It takes a little extra effort, but I’m now at the point where I can confidently create a better RAW file conversions than I could using standard Adobe Raw profiles. There is more flexibility in the basic and color adjustments, the sliders are more predictable, and it’s easier to recover good shadow and highlight detail. Overall, the output from Camera Raw is more pleasing, and I’m able to finish the image in Photoshop faster. I hope you’ll give linear profiles a try and see what they can do for your images.

The video below by Dave Kelly reviews the basics of adding a linear profile to your workflow.