Recently I wrote a small photoshop technique article covering image blending for Popular Photography magazine and thought it might be of interest to readers of my blog. I don’t blend images all the time but it’s a nice technique to have up your sleeve when an image isn’t captured perfectly in camera. The above top image is straight out of the camera from Liffey Falls, Tasmania and was slightly under exposed which meant detail was lost around the foliage area near the waterfall itself. I used image blending in the bottom half of the image to bring out detail of the foliage area whilst not blowing out the highlights of the waterfall itself.
To begin with, we must first have two images which we will use for blending. One image will act as the base image (this under exposed image) whilst another will be used to blend into areas of the photograph. I exported this image from my raw editor (in this case Lightroom) with an exposure of 0.00.
Now we will export the second image which will be used for blending into the base image. This time when exporting I have bumped the exposure from 0.00 to +1.52. The image is now quite over exposed especially with the highlights of the waterfall. This will be fixed when blended.
Open the base image in Photoshop. This image is deliberately under exposed so I can retain the exposure of the waterfall stream.
Open the second (brighter) image to be used for blending. We want to place this as a layer above the under exposed base image. Do this by selecting Select > All and copy this by Edit > Copy. Return to your base image and paste this new layer by Edit > Paste.
Now the image is added as a layer above our base layer, we are now ready to create a layer mask which will allow us to blend the image with our base image. Create a layer mask by selecting the layer mask icon as circled or Layer > Add Layer Mask.
The brush tool is used for layer masking to bring out the areas which we want to blend. Select the brush tool from your sidebar or by pressing B. We must also change the colour of the colour palette to black and white. Through doing so, black allows us to paint over the area we wish to blend whilst changing the colour to white will act as an eraser and allow us to correct areas which we have painted with black.
For this image I’ve painted over the waterfall area as this is the only part of the original base under exposed image I wish to retain.
Layer masking isn’t only just helpful for blending exposures and also allows for selective editing. By using curves, this will allow me to bring out the green foliage area more. Create a curves layer mask by selecting Layer > New Adjustment Layer > Curves or otherwise press the Create a new fill or adjustment layer next to the layer mask button as circled.
For the image I slightly adjust the highlight and shadows section of the green channel within curves. My best advice for curves is to just experiment. I’m looking to subtly bring out the green foliage to better reflect the scene when I photographed it.
Similar to earlier steps, I now paint over the non foliage areas with a black brush. This allows me to make adjustments only to the foliage area whilst avoiding a green tinge to the rest of the image.
Now I wish to do similar but this time adjusting the colour of the water ever so slightly. I do this again by Layer > New Adjustment Layer > Curves and selecting the blue channel. Once again, I play until I get the desired result.
Once again I now use the paint brush tool set to black which allows me to paint over non water areas to avoid giving the whole image a blue tinge. This completes the tutorial on using layer masking and image blending in Photoshop. Normally I would now do some minor dodge and burning, resize for web (800px at longest end) and apply USM sharpening.
If you have any questions about this photography post processing tutorial or require additioanl assistance drop me a message via the contact page and I’ll do my best to help.