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iPhone Infrared Hot Spots
Three Ways to Fix in Post
Free video
How I Did It!™ iPhone Infrared Hotspots; Three Ways to Fix in Post Processing.
Whether you’re photographing infrared with your big camera or your iPhone, occasionally you may have a hot spot in the middle of your photo. Some big camera lenses are known for hot spots at specific focal lengths, and when using filters with an iPhone hot spots can occur depending on filter brand, brightness, and the angle of the camera to the sun. Despite efforts to prevent creating hot spots when photographing, sometimes they can’t be avoided.
Rather than toss those images in the reject bin, here are three different methods I use to address hotspots in post processing.
Here, I’ll be addressing hotspots in iPhone images using iPhone apps, but similar processes can be applied to big camera IR images with desktop software. (The Lightroom Mobile techniques mentioned here can also be done in Lightroom Classic on the desktop. The masking process is very similar.)
Of the two tools I use most and will be covering in this post — SnapSeed and Lightroom Mobile — I prefer Lightroom Mobile. Both apps work equally well on iPhone and Android.
Since not everyone uses the subscription app, Lightroom Mobile, I’ll start with the process for eliminating hotspots using the free app, SnapSeed.
You'll find a step-by-step guide to each of these processes below, and, for more guidance, see my free video, How I Did It!™ iPhone Infrared Hotspots; Three Ways to Fix in Post Processing.
SnapSeed Processing Workflow 1:
Using the SELECTIVE Tool
- If working with a RAW file, process the RAW file using a RAW editor (such as the iOS editor) then, open the image in SnapSeed.
- Examine the image to determine the extent of the hotspot and its boundaries in the image.
- Open SnapSeed’s SELECTIVE tool. Make sure the plus sign (+) is blue and tap the image to place a control point in the center of the hotspot on the image. Using the two finger gesture, adjust the control point to fit precisely over the hotspot area. Now you are able to adjust for Brightness, Contrast, Saturation, and Structure within that area defined in the control point.
- Now, decrease the brightness of the defined area over the hotspot until it matches the brightness of the surrounding area. You may be tempted to adjust for the other variables in the control area, but I’ve found it best to match the brightness in the control area with the surrounding area, then make any other image adjustments, such as contrast or structure, globally.
- If the hotspot covers a large area, you may need to places two or more control points in the hotspot area to completely eliminate the hotspot.
SnapSeed Processing Workflow 2:
Using the Masking Tool
Another method involves using SnapSeed’s powerful masking capability.
- If working with a RAW file, process the RAW file using a RAW editor (such as the iOS editor) then open the image in SnapSeed.
- Open the TUNE IMAGE tools. Using a combination of the BRIGHTNESS and HIGHLIGHTS sliders, drop the brightness and highlights until the hotspot is the desired brightness, matching that of the surrounding image. These adjustments will darken the entire image, not just the hotspot area but that’s okay because using the masking tool, we’ll selectively apply that darkening just to the hotspot until it matches the surrounding image in brightness.
- Tap on the history button and select VIEW EDITS.
- Locate the TUNE IMAGE adjustment layer on top, then tap the layer and select the brush from the menu that appears.
- This opens SnapSeed’s masking tool. Notice that when the masking tool opens, it shows the image without the darkening adjustment that you just applied using brightness in Tune Image. SnapSeed is within for your instructions as to where to place that darkening.
- Use your finger to paint in the darkness over the hotspot in the image. If you set the eyeball icon to be blue, you’ll see a pink mask showing the area you are brightening. Sometimes turning on the eyeball is helpful and sometimes you can see what you’re doing without that feature turned on.
- If the area you paint in is too dark, you can drop the percentage of coverage from the default 100%, to 75, 50, or 25% by tapping the down arrow in the toolbar. To erase an error, drop the percentage to 0 and paint over your mistake. The goal is to match the brightness of the hotspot with the rest of the image.
- If the hotspot has been eliminated, you’re finished. But if the hotspot is still visible, you can tap the slider icon in the Tune Image layer and further adjust the brightness. Since the mask is already there, any adjustment to brightness will apply only to that masked area over the hotspot.
Whichever of these two SnapSeed methods you use, once complete, you can now continue with your remaining processing.
If you are interested in a more in-depth SnapSeed tutorials, see my video tutorial,
How I Did It! ™; The Magic of SnapSeed!
Use Lightroom's Masking Tool to Eliminate Hot Spots in Your IR Images
While SnapSeed works fine, I prefer using Lightroom Mobile for it's superior masking capability and because it is a great RAW file editor. (SnapSeed does have a RAW editor, but I find it inferior to what we have in the iOS editor and especially to Lightroom Mobile.)
Using Lightroom Mobile, I can do my RAW processing and all the other editing and be finished, or, I can move to another app, like SnapSeed for finishing touches.
A Word about Lightroom
If you subscribe to the Adobe Creative Cloud for desktop software like Photoshop and Lightroom Classic, the Lightroom Mobile app is included in what you're already paying for the subscription; there's no extra charge for Lightroom Mobile.
If you don't want to subscribe, you can still get a free version of Lightroom Mobile, but it will be lacking these tools: Healing, Geometry, and most importantly, Masking.
Lightroom Processing Workflow:
Using the Masking Tool
See the steps below and if you need more guidance, watch my free video, How I Did It!™ iPhone Infrared Hotspots; Three Ways to Fix in Post Processing.
- Open any file in Lightroom Mobile, and apply your Lightroom editing workflow. (See my video, How I Did It!™ Lightroom for iPhone and Android for my Lightroom editing process.).
- After completing your editing workflow, if the hotspot persists, open Lightroom's Masking feature.
- Click the blue + sign and select the radial gradient.
- Draw the radial gradient to cover the hotspot. Use the brush adjustment on the left side of the interface, to ensure a soft edge to the radial mask.
- With the Mask positioned over the hotspot, now the adjustments you make with adjustment tools will affect only that masked area.
- Open the Light adjustment tool and use the Exposure, Highlights, and Shadow sliders, moving them until the hotspot matches the surrounding area. Just like in SnapSeed, avoid making other adjustments to just the small area.
- After you've matched the hotspot so that it blends in with the surrounding area, continue making any other global adjustments that you'd like.
- Alternatively, if the hotspot is covering a are with lots of contrast, you can also choose the brush instead of the radial gradient, and paint in the areas that you are trying to match with the rest of the image.
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