How to Blend Bracketed Exposures in GIMP

Exposure blending in GIMP is a manual technique used to merge multiple bracketed landscape shots into a single high-dynamic-range image without the artificial, halo-heavy appearance often produced by automated HDR software. By loading bracketed images onto separate layers and using layer masks with soft brushes, gradients, or selections, you retain complete control over highlight and shadow transitions. This guide outlines the precise steps required to align your shots, create effective layer masks, and seamlessly blend the frames for a clean, natural landscape photograph.

Step 1: Import Bracketed Frames as Layers

  1. Open GIMP.
  2. Go to File > Open as Layers...
  3. Select your bracketed RAW or converted TIFF/JPEG files (typically an underexposed frame for skies/highlights, a base exposure for midtones, and an overexposed frame for deep shadows).
  4. Click Open to load the images into a single project.

Step 2: Align the Layers

Even when using a sturdy tripod, minor shifts can occur between exposures:

  1. Select the top layer and change its Mode to Difference in the Layers panel.
  2. If the alignment is slightly off, you will see bright edges. Use the Move Tool (M) to nudge the layer until the canvas turns as close to solid black as possible.
  3. Switch the layer mode back to Normal.
  4. Repeat this check for each layer relative to the base exposure.

Step 3: Organize the Layer Stack

Arrange your layers logically from brightest to darkest:

  1. Place the normal (mid-tone base) exposure at the bottom of the stack.
  2. Place the shadow exposure (brightest frame) in the middle if needed.
  3. Place the highlight exposure (darkest frame, used for sky and bright spots) at the top.

Step 4: Apply a Layer Mask to the Highlight Exposure

  1. Right-click the top (darkest) layer in the Layers panel and select Add Layer Mask...
  2. Choose Black (full transparency) and click Add. The dark layer is now completely hidden, revealing the properly exposed midtones beneath.

Step 5: Paint the Highlights In

  1. Select the black layer mask thumbnail in the Layers panel.
  2. Choose the Paintbrush Tool (P) and set your foreground color to White.
  3. In the Tool Options, select a large, soft brush (such as Hardness 050 or lower), reduce the Opacity to 20–30%, and increase the brush size.
  4. Gently paint over the blown-out regions (like skies, sun reflections, or bright clouds). Because the brush opacity is low, each stroke gradually brings back detail from the underexposed frame, ensuring smooth, halo-free transitions.
  5. If you paint over an area by mistake, switch your foreground color to Black and paint over the region to conceal the dark layer again.

Step 6: Blend the Shadows (Optional)

If your base exposure has harsh, noisy shadows:

  1. Move the overexposed (bright) layer directly above the base layer.
  2. Add a Black (full transparency) layer mask to it.
  3. With a soft white brush at low opacity, paint over the underexposed shadows (such as dark foreground rocks or dense foliage) to naturally lift details.

Step 7: Final Global Adjustments and Export

  1. Right-click anywhere in the Layers panel and select New from Visible to create a merged layer at the top of your stack.
  2. Use Colors > Curves... or Colors > Levels... on this new layer to set your final black and white points and restore global contrast.
  3. Go to File > Export As... to save your final blended image in your preferred format.