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590 nm Infrared image with hot spot corrected
590 nm Infrared image with hot spot corrected

The short answer: the best fix for a hot spot is a lens that doesn’t produce one. For an image you can’t reshoot, there are three fixes. A mild hot spot can be neutralized in your raw editor with inverted radial masks that correct temperature, tint, and exposure. A hot spot that mostly drains saturation can disappear in a black and white conversion. A stronger hot spot can be fixed by selecting it with Color Range and correcting it with adjustments.

In this video, I’ll take a look at a few methods for fixing infrared hot spots. Hot spots are produced by certain lenses when shooting infrared photography. Since lenses are designed for visible light, many will not produce optimal results with infrared light. Mild hot spots can be addressed easily in Lightroom or Photoshop. Severe hot spots can be very challenging to fix. In the long run, you will be better off shooting your infrared images with a lens that does not produce hot spots. However, these techniques could be helpful for an image you’ve already captured and cannot recreate.

What Is a Hot Spot?

Lenses are designed for visible light, and some of them behave differently with infrared light. They create a bright, overexposed spot in the center of the frame. The hot spot gets stronger as you stop down. In my comparison from ƒ/2.8 to ƒ/22, the spot is faint wide open, then becomes more intense and more focused at each smaller aperture.

Some hot spots are obvious, with rings and flare around a bright center. Others are subtle. A hot spot doesn’t just change exposure. It can also shift white balance, and color saturation in the center of the image.

Step 1: Avoid the Hot Spot

Research a lens before you shoot infrared with it. Check the Infrared Lens Database, or test the lens yourself. Every fix below is time consuming, so a hot spot free lens saves you far more time than any editing technique.

How to Detect a Subtle Hot Spot

Use the white balance picker in your raw editor. Apply your infrared profile, then click a neutral subject such as clouds near the edge of the frame, outside the hot spot. Then click the same kind of subject in the center. In one of my images the edge read 3700 K and the center read 4700 K. A difference of about 1000 K between edge and center means a hot spot is shifting your colors.

Fix 1: Radial Gradiant Masks

This works well for mild, broad hot spots, which are the most common kind.

  1. Apply a profile and white balance. Set your infrared profile and white balance on a neutral subject near the edge.
  2. Make the hot spot visible. Turn vibrance and saturation all the way up. The hot spot often shows up as several concentric rings around a bright center.
  3. Add a radial mask and invert it. Drag it a little wider than the ring you’re correcting so the feathering has room to blend. Hold Shift for a perfect circle.
  4. Correct the color. Temperature is usually the biggest problem, then tint. A color swap profile reverses the sliders. To make a ring bluer, you may have to move the temperature slider toward yellow.
  5. Work from the outside in. Add one mask per ring. The effects stack, so each inner mask needs less correction. Adjust exposure and saturation on the center ring, where the brightness is.
  6. Adjust the feather. A low feather gives a hard edge. Widen the mask and raise the feather until the edge disappears.
  7. Turn vibrance and saturation back down. With saturation exaggerated you only need to get close. Once you return to normal settings, small leftovers are usually invisible.

Overlapping mask pins are hard to select. Zoom in with the navigator to separate them.

Fix 2: Convert to Black and White

Some hot spots mostly reduce saturation, with little effect on brightness. If the image doesn’t depend on color, try a black and white profile, then raise contrast, clarity, and dehaze. A saturation hot spot often disappears in black and white.

Fix 3: Color Range in Photoshop

This is the most advanced technique, and it handles hot spots that Lightroom can’t.

  1. Swap the colors. Open the image in Photoshop and swap the channels with a channel mixer. My free Photoshop Actions for Infrared do this in one click.
  2. Select the hot spot. Go to Select > Color Range and choose Sampled Colors. Click the center of the hot spot, then use the plus eyedropper to add more of it. Adjust fuzziness until the selection fades toward the edges. The selection has to be a little larger than you’d expect, because Color Range only selects pixels that are at least 50 percent selected.
  3. Add a Vibrance layer as a viewing aid. Turn vibrance all the way up so you can see your corrections, then hide it when you’re done.
  4. Add a Color Balance layer. It uses the selection as its mask. Shift the cast toward its opposite, mostly in the highlights, a little in the midtones, and only occasionally in the shadows. Photoshop’s Color Balance is the real advantage over Lightroom here.
  5. Reuse the mask. Alt-drag (Option-drag on Mac) the mask to an Exposure layer and darken the hot spot slightly, about a third of a stop. Copy it to a Hue/Saturation layer the same way if the saturation needs to match the rest of the image.

Toggle the Color Balance layer to compare before and after.

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