Focal length blending with luminosity masks

Luminosity masks are of course enormously popular for exposure blending and dodging and burning. But that’s really just the tip of the iceberg. You can use luminosity masks for a huge range of creative post-processing techniques, including “focal length blending”.

Focal length blending involves combining two or more images shot using different focal lengths. Sounds bizarre or impossible, but it’s an incredible way to captures landscapes that you simply cannot capture in one frame. For example, you may run into a scene where the foreground requires a wide-angle lens to get great leading lines while the background requires a longer focal length to keep from looking tiny. That’s exactly the scenario I was facing when I shot the image below and shot at 16mm to capture the gorgeous waves and then zoomed to 35mm to capture the sea stack large enough to show its glory.

 

The techniques used here should feel somewhat familiar if you already understand exposure blending. You paint through luminosity selections to create a mask that reveals one layer on top of another. In this case, to reveal the 35mm sea stack on top of the 16mm image. There are of course additional considerations. You’ll need to align your images before blending. And a credible blend may require some additional creative work.

The trickiest and most unique part of this blend is the reflection. You have to create it. You can’t use the 16mm reflection because it’s too small. And you can’t use the 35mm reflection because it doesn’t match the image at all. The key is recognizing that the reflection is basically appearing as a dark pixels in the shadows of the foreground. So we can create create a fake reflection using a fill layer and luminosity selection.

Milky Way Blending with Nick Page

Nick Page just did a great webinar on processing Milky Way and Aurora images with Rafael Pons of PhotoPills. During their talk, Nick discusses what makes for strong images, camera techniques, and how he uses Lumenzia to create luminosity masks and bring out the best in challenging night skies.

Note that if you want to jump right to his exposure blending, you can see that around 45, 58, and 80 minutes into the video.

A few quick tips you can take away from Nick’s demonstration:

  • Processing your image multiple times and blending them together with luminosity masks is a great way to adjust your foreground and sky independently to get the most from your RAW files. You can see this around 4o minutes into the video.
  • Customize your luminosity mask preview by double-clicking the levels adjustment layer to bring in the white and black sliders to help further isolate the sky from the foreground. You can see this at the 45:30 mark.
  • You can also customize the luminosity mask preview by color easily by double-clicking the orange “Color Conversion” layer and adjusting the sliders to select more or less of specific colors you wish to include or exclude. You can see this at 59 minutes.

Nick also has an excellent collection of tutorials to go deeper on a wide range of landscape topics.

How to remove hot pixels from long exposures

In long exposure and low light photography you’re faced with noise and potentially “hot pixels“. While noise is frustrating, hot pixels are devastating. If they aren’t removed, the image is severely affected for any close viewing or printing. Traditional noise reduction techniques aren’t designed to fix hot pixels and cloning potentially thousands of bad pixels individually from an image is no one’s idea of a good time. Thankfully, there’s a must simpler fix and you’ll learn all about it in this week’s tutorial.

To remove hot pixels with the Dust & Scratches Filter:

  • Duplicate your layer (or image via ctrl/cmd-alt/option-shift-E) or convert it to a Smart Object to work non-destructively.
  • Go to Filter / Noise / Dust & Scratches.
  • Zoom in to at least 100% and start with both sliders to the far left.
  • Increase the radius slider by one at a time until you find the smallest number that gets rid of most or all hot pixels. Do no go above this, as you will lose only lose image detail. This is typically 2-4.
  • Increase the threshold slider until you find the largest number that does not re-introduce the hot pixels. This slider helps restore detail and grain in the image. Typically 5-10 is a good number, but you may go higher. Click OK when done.
  • This filter is safe to apply to color nearly everywhere, but needs to be applied judiciously to the luminosity in areas of detail. So use the following two-prong fix:
    • Create a duplicate of the fix and set one copy to “color” blend mode.
    • For the “normal” blend mode version, add a black layer mask and then paint white to reveal the full fix as needed. Use selections to help make the painting faster and more precise.
  • There may be a few stubborn hot pixels that aren’t removed by the filter. Just create a blank new layer and use the spot healing brush (set to sample all layers) to finish.

 

If you’re working on night images, this is also a great way to fix the foreground. If you’re trying to clean up a starry sky, you might wish to apply this more selectively with a brush or using color options in Lumenzia in order to avoid applying this filter on stars (since it will suppress them).

How to Use Content-Aware Scale in Photoshop

Photoshop contains a lot of hidden gems. One of them is certainly the “Content-Aware Scale” (CAS) tool. This feature is perfect for expanding the sky or background, scaling the image to fit a specific form factor for sharing online or printing, or even shrinking the image (such as to turn a regular image into a panoramic format).

CAS offers two incredible advantages over simply enlarging or shrinking your image. First, it is an intelligent tool that does a pretty good job on its own of preserving the most important detail rather than blindly changing the size of everything. Second, and this is where things get really powerful, it lets you directly specify which areas to protect and which can be stretched or compressed. In this tutorial, you’ll see just how powerful it can be, learn the basic workflow to use it, and some advanced techniques for pushing it to the limits.

 

Note that I push the second demo image to the extreme by converting a lanscape image to a square crop. This can be useful for posting to a platform like Instagram. But regardless of whether you would personally change this image in this way, the key lesson is that you can substantially enlarge your sky with the right workflow when needed.

 

The general CAS workflow is:

  1. Create a selection of the area you wish to protect. A rectangular marquee works very well. Alternatively, you may wish to use Quick Select on the sky and then invert to target the foreground. Don’t worry about being pixel perfect with the selection, you just need a reasonable target to get good results.
  2. Save the selection as a channel via the Channels Panel or Select / Save Selection. It helps to rename the channel here to find later it in the steps below.
  3. Deselect via <ctrl/cmd>-D. If you leave the selection active, you only transform the selected area and won’t get good results.
  4. If you are enlarging the image, expand the canvas with the crop tool (<C>). Leave the “content-aware” box unchecked in the crop tool. If you are trying to hit a target aspect ratio, enter value in the crop box and you’ll be able to use it to both visually crop in one dimension while expand to fill the other.
  5. If your target layer is locked (including background layer), click the lock icon to unlock the layer.
  6. Go to Edit / Content-Aware Scale.
  7. Change the “Protect” dropdown from “none” to your saved selection.
  8. <shift>-click and drag to scale the image without being constrained to the original proportions. Watch out for artifacts with significant resizing, especially in the main subject or areas you cannot easily clone.
  9. You may wish to compare setting “protect” to none or try a few different selections to see which produces the best result, especially when you are first learning the tool or working with complicated images.
  10. Click the check mark when you are finished.
  11. Delete your saved selection by dragging it to the trashcan in the Channels Panel. Keeping it increases the saved file size.
  12. If you were not able to stretch as far as you needed. You have several options:
    • Use the double-stretching technique below to repair artifacts that show up with large stretches.
    • Use Content-Aware Crop to expand further at this point (without adding artifacts to your existing work).**
    • OR, use a little Content-Aware Crop BEFORE you use CAS. In this workflow, you expand the canvas a little (within the limits of what the cropping tool does well) and then expand it further using CAS. This is a great approach that often works best by making the most of two great tools.
    • Use the spot healing brush, regular healing brush, or clone stamp. This works well when there are just a few artifacts or they are mostly in simple areas like clouds.
    • Use a Edit / Transform or Image / Image Size to finish expanding. This will affect the entire image, but you’re working from a better starting point than using these tools directly on the original image.

** You can of course increase the sky using just the content-aware crop tool without CAS. This has the advantage of simplicity as you don’t have to create a channel. It also avoids any stretching of the original image and only fills in the expanded canvas. It’s a great tool for slight expansions or for images where you absolutely want to avoid stretching or distortion. However, it can create strange artifacts and CAS often excels for more significant expansions. CAS can also be used for shrinking/compressing the image as well. Ultimately, they are both great tools and using them together is often an ideal way to get the best results.

 

If you push CAS too far, you are going to run into artifacts. If you run into more significant artifacts, you can use some creative blending to things work in order to achieve greater enlargement. As shown in the tutorial above, the following double-stretching technique is a great workflow to push the limits with CAS:

  1. Duplicate your original layer and then use the CAS workflow above on one of the layers. You’ll use the other layer for the rest of the steps below to create a stretched version without artifacts in your subject.
  2. Put the unstretched layer on top, change it to “difference” blend mode, and use <ctrl/cmd>-T to transform it. As with the CAS tool, hold <shift> to resize without constraint. The goal here is to stretch this copy until it covers the edge where the subject meets the sky (and the difference blend mode will help you easily assess the alignment). The transform tool will not create artifacts, so this is your clean copy and you just need to blend it into the CAS version now.
  3. When it is aligned, accept the changes and switch back to “normal” blend mode.
  4. Add a white layer mask to your cleanly transformed layer.
  5. If you want to protect the subject when blending, create a selection of the sky and contract/feather it.
  6. Now paint black on that layer mask to hide the clean sky. This will reveal the CAS sky and eliminate any edges shown between the two.
  7. If you have any artifacts in the CAS sky, you should be able to easily fix them with the spot healing tool.

Create beautiful web-sharpened images with grain

I’ve received a lot of great feedback and suggestions since I originally launched my free web sharpening utility. My friend Suhail had an excellent suggestion to add the ability to add some grain to the final output. This can help give the finished image a bit of a dreamy, nostalgic quality that is reminiscent of shooting with film. In this tutorial you’ll learn how you can easily use the new version to add some grain while creating perfectly sharpened images for the web.

 

Controls for grain include:

  • Amount: Controls the amount of grain applied overall. 7-15% is typically ideal. Set to 0% to disable grain.
  • Size: Controls grain particle size. 25% is the default. Try much higher values to make the grain look softer / less noisy (note that values >25% may slightly blur the image detail).
  • Roughness: Controls the regularity / uniformity of the grain. 50% is default and often ideal. Try higher values if you want a slightly textured look (this may appear blotchy on very smooth areas).

For ultimate control, hold <ctrl/cmd> while clicking “Sharpen” to leave a layered version of the image open. This allows you to control the local sharpening and grain using the following workflow:

  1. Optimize the grain on the sharpened layer by double-clicking the “Camera RAW Filter” on the top layer, heading to “Effects” and adjusting the grain, size, and roughness. This allows you to optimize these sliders visually. It is best to do this first, as the grain affects the apparent sharpness and therefore affects how much you might paint on the masks.
  2. Use a soft brush (and selections as needed) to paint dark gray on the filter mask in areas where you wish to reduce grain. Using dark grey paint (rather than black) helps ensure you retain a minimum amount of grain in all parts of the image.
  3. Use a soft brush (and selections as needed) to paint black on the layer mask in areas where you wish to reduce sharpening (as this will allow the “no sharpening” layer to be visible from below).
  4. You may now wish to apply the same grain values from the sharpened layer to the “no sharpening” layer. Failure to do so may reveal inconsistent results or may look noisy if the underlying area retains grain you just removed.
    • Duplicate the Filter Mask so that the areas that get grain are consistent between the layers. Hold down <alt/option> and then click and drag the top filter mask down over the lower layer. You may continue painting on the Filter Mask if you need to further reduce grain, but that’s generally not necessary. **
    • If you significantly adjusted the values in ACR, you may also wish to apply the same slider values to the lower layer. A quick way to do that is to delete or hide (click the eyeball icon) the existing Camera RAW Filter and then hold <alt/option> to click and drag from the top layer to the bottom to duplicate the filter just like you did with the mask. **

** When duplicating masks or filters in Photoshop, you must hold down <alt/options> BEFORE to click and drag. If you start holding that key after clicking, it will be ignored and you will move the mask/filter instead of duplicating it.

 

For a more complete demo on the web sharpening utility, please see the original tutorial and demo. This script has received several bug fixes and enhancements since the original launch and you may read more about them in the version history text file in the download.


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