Masking and Exposure Blending in Photoshop

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This tutorial is a way of blending multiple photographs into a single composition to create a high dynamic range image (HDR image). Essentially what you are going to be doing is creating two images, one exposed for the highlights, and one for the shadows. Then we'll blend them together using whats called a layer mask. The reason for doing this is that cameras can only capture about 3-4 stops of dynamic range (tonal range from highlights to shadows), while our human eyes capture about 10-stops of dynamic range. So what we'll be doing is trying to increase the dynamic range, resembling the scene we saw in real life.

First off, there are two ways you can go about doing this:

a.) You can shoot in RAW format, an uncompressed file format that allows you to change white balance, exposure compensation, etc in the computer with little file corruption and then process 1 image twice.

b.) You can shoot two images at different exposures on a tripod.

In this tutorial I'm going to use method a, but its the same proceedure for method b as well.

First off, you'll want to open your image in Photoshop. Now if you are working in RAW, you will see the ACR (adobe camera raw) screen. Before you start tweeking your image, remember: Anything you cange will have to be changed twice, once for the image you are editing, and once for its duplicate. For example: If you change the white balance to "auto", from "as shot" you will have to do the same for both images.

http://www.markdelbrueck.com/blending/raw.jpg

Look at the two things I circled in blue. The first is the exposure. You will want to uncheck the "auto" button, and adjust the image for the highlights. Typicallly this means that you are adjusting the image to show a greater tonal range in the foreground. Doing this will ruin your beautiful sky, but not to worry, we'll bring it back later on. Normally, I adjust the exposure value (ev) to +1.0 for the highlight image.

One more thing to notice: Do you want to work in 8-bit color or 16-bit color? If you plan on going on and doing tone mapping and or printing, then 16-bit is your key. If not, I just normally work in 8-bit because its faster.

http://www.markdelbrueck.com/blending/light.jpg
(exposed for the shadows/dark areas. Note: the sky and highlights are blown out)

Click Open. Next you'll want to go back to your folder where the image first off came from, and re-open it in photoshop. The only thing you'll need to change the second time around is the exposure value (ev). This time we'll be exposing for the shadows (background, sky, etc). So move the slider to -1.0 and click open.

http://www.markdelbrueck.com/blending/dark.jpg
(exposed for the highlights/light areas. Note: the dark areas are realllyyy dark)

You should be left with two images open now.

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Alright, next we are going to make the selection so we can blend the two images into one. For that, we are going to use a layer mask as opposed to getting out the ole' lasso tool. This way is more accurate and MUCH quicker. with your highlight image active, hit the Q key on the key board and if your hotkeys are set to default, you should enter quick mask mode. Essentially what your going to do is use the brush tool and paint where you want your selection to be.

http://www.markdelbrueck.com/blending/masking_1.jpg

Don't worry about the "pink" paint, its not going to effect the image. The key to making this work is in the details... don't be afraid to zooooom in and get in the grooves. The most frustrating scenes involve tree and timberlines! Clean horizons are a piece of cake.

http://www.markdelbrueck.com/blending/masking_details.jpg

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Finalize your selection and hit the Q key again. This will leave you with a selection around your image. But your not done yet. Go to select>inverse and you'll have the final selection.

http://www.markdelbrueck.com/blending/selection.jpg

Use the move tool (hotkey v) and move the selection onto the shadow image. So recapping, you should have two layers now, the background, which is your image that is exposed for the shadows,and layer 1 which contains the selection and bottom half of your image exposed for the highlights.

http://www.markdelbrueck.com/blending/layering.jpg

Notice: now you are exposed properly for both the highlights and shadows.

Ok now no matter how good of a selection you've made, you will have some "ghosting" or "halos" around where your foreground meets your background. Just zoom in and use the eraser and carefully erase these:

http://www.markdelbrueck.com/blending/erase.jpg

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Finally you'll want to do some color adjustments, because chances are that its not going to look all too natural with the foreground exposed so perfectly. For this, I apply some levels to layer 1.

http://www.markdelbrueck.com/blending/levels.jpg

http://www.markdelbrueck.com/blending/levels_2.jpg

I also tone down the saturation and brightness of the foreground layer (layer 1) for a more natural look.

After fixing the crooked horizon and doing some final sharpening, here is the final blended image (as you can see, I got lazy and dind't finish my erasing):

http://www.markdelbrueck.com/blending/final.jpg

Hope this helps, and I can't wait to see some of ya'alls results!