Thursday, August 20, 2009

How to make a surreal faux HDR image

Introduction

I recently ran across this Russell Brown PhotoShop tutorial wherein he presents a technique to make what he calls a Faux HDR image. This doesn't really have much to do with HDR other than taking a single image and giving it a surrealistic, over-the-top, tone-mapped HDR look. It does not take a scene and get more dynamic range out of it as is typical with HDR. It does take a scene with a compressed dynamic range and expands it to make it brighter while at the same time it boosts color brightness and saturation. You can go watch the video here or, if you're like me and aren't a fan of video tutorials, you can read about it below.

Best types of images

This technique works best on images that are not blown out but where the detail is tightly compressed. Typically this happens when a scene is exposed for a bright section, so it's not over exposed, but has lots of dark areas causing important detail to be hidden in the shadows. For the purposes of this tutorial, I'll be using this example image I took on a recent Photowalking Utah event.


As you can see from the histogram, this image has a large bump on the left and a smaller bump on the right indicating a lot of dark and light areas whereas the middle area does not have much going on. The dark areas are not underexposed nor are the light areas overexposed. This can be seen by the two triangles in the top left and right corners. The one on the left will change color when there are details lost in the shadows and the one on the right when the brightest areas are overexposed.


For comparison, here is a similar image that does not work well. It is exposed for the darker areas as evidenced by the wider and smoother bump on the left side. Unfortunately, this causes the highlights to be overexposed and the cloud detail to be lost as seen by the sharp spike on the very left side.

In Camera Raw

The majority of the work will be done in Camera Raw, prior to going into PhotoShop. First, open your image and verify there are no blown out details. As intimated earlier, look on the histogram for images without spikes going off either edge. If you click on the triangles at the top right and left corners of the histogram, Camera Raw will change all the overexposed sections to red and the underexposed sections to blue as a means of highlighting the areas that have lost detail.

Now to get into the main changes. We're going to be manipulating primarily the Exposure, Recovery, Fill Light, Blacks, Clarity and Vibrance sliders. We'll start at the top of the list and work our way down. When we get to the bottom, we'll evaluate the image and possibly go back to the top to make some fine tuning adjustments.

Exposure

The exposure will typically need to be adjusted. If on the histogram, the dark area is larger, such as on this example image, then typically the exposure will need to be increased. On the other hand, if the bright area is larger, then it'll need to be decreased. On this image, if I increase it at all I'll start blowing out details in the bright areas, so for now I'll leave it at 0.

Recovery

Recovery pulls the brighter parts of the image down and gives us some headroom on the right side of the histogram to additional changes. This technique typically works best with this set the maximum, so that's where I'll put it for now.

Fill Light

Fill Light brightens the dark areas without blowing out the highlights. Again, the images that work best with this technique usually like this set to the maximum.

Now that we're about half-way through this first part, we can see our image is quite a bit brighter, but has sort of a flat appearance to it.


We can see in the histogram the data is spread apart rather than being bunched up on the two sides. The remaining steps in this section will help give the image some more depth.

Blacks

Now to get rid of that flat look, we're going to increase the Blacks slider. Adjust it so the dark regions are just starting to clip, as indicated by the blue highlights that Camera Raw shows us. For this image, a value around 40 works well.

Clarity and Vibrance

To get that surrealistic look characteristic of overly tone-mapped HDR images, we're now going to slide both the Clarity and Vibrance sliders all the way to their maximum values.

Fine tune adjustments

Now that we have all the basic adjustments done, we need to evaluate where we are. At this point, this image is still pretty dark. To lighten it, I go back to the Exposure slider and find I can now push it quite a bit. In fact, I can increase the exposure by 2.5 stops without clipping. If I increase it more, then I start blowing out my sky which I don't want to do. By leaving detail in the sky, even though it's not too visible at this point, I'll have something to work with later to improve it.

Now we're done with the controls on the first panel.

 
 

The next step is to do some adjustments on individual colors. To do this we go to the HSL / Grayscale tab.


And once there, we click on the Luminance tab.


These controls allow us to change the brightness levels of various color groups. What we change and the amount we change it will vary from image to image. On this image, I find that decreasing the Blues and increasing the Purples significantly helps my sky. Based on this discovery, I go over to the Hue tab and find I can help the sky some more by sliding the Purples and Oranges over to the right to around 65. This brings out the colors in the sky and flowers even more. This is an area where experimentation on each image can yield dramatic results.

If you so desire, you can crop the image and apply a vignette. The cropping tool in the top toolbar works well to remove those parts of the image you don't want and the vignette control on the Lens Correction tab allows you to highlight the center of the image. I choose not to do that on this particular one.

Open in Photoshop

We're now done with our edits in Camera Raw. Just prior to opening the image, make sure the color depth is set correctly and smart objects is enabled. To do this, click on the label that is centered at the bottom of the Camera Raw screen containing information about the color mode, bit depth, image size and resolution. This will open a dialog. Make sure the Depth is set to 16 bits/channel and the checkbox for smart objects at the bottom is checked. Close the dialog and then click the Open Object button. Doing this will ensure there is no loss of color information in the transfer to Photoshop and the background will be configured as a smart object so edits will be non-destructive.

There are many things that can be done to the image at this point. One of the more common ones for this type of image is to adjust the Shadows and Highlights found on the Image / Adjustments menu. Quite often this type of image can be further enhanced by selectively adjusting contrast in different regions of the picture. I found on this particular one this didn't help, but it has on others.

Sharpening is another thing that typically enhances most images. The use of either Smart sharpen... on the Filter / Sharpen menu or my High-pass sharpening action can be used. The Smart sharpen tool can give a very edgy look by pushing the controls to high values. My action will give a less edgy look.

After some tweaks to the sky, this is my final version of this image.

And here are a couple of other images processed with this technique.
Albion morning

Red, White and Blue

Summary

In closing, here is an outline of the steps covered above.
  • Camera Raw
    1. Exposure: over or under as dictated by image.
    2. Recovery: typically 100%
    3. Fill Light: typically 100%
    4. Blacks: typically 30-50%
    5. Clarity: typically 100%
    6. Vibrance: typically 100%
    7. HSL / Luminance: as needed for iamge
  • Photoshop
    1. Image / Adjustments / Shadows and Highlights: as needed
    2. Filter / Sharpen / Smart sharpen: as needed
    3. Anything else: as desired
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