Another thread got me to thinking about posting this one. It's something I've been meaning to post, but just hadn't found the time. But, let's talk Pseudo HDR!
What is HDR?
First, let's talk about what HDR is. Said simply, High Dynamic Range photos show more of a range of stops than is normally possible. A normal digital camera sensor can display about a 6 stop range. Some less. Very few can display more. This means that from black to white everything in the photograph is within 6 stops.
If you think about most real life outdoor scenes, that's very limiting. When everything is in full sun or full shade, it's fine -- but when there is a mix of both, 6 stops won't cover it well. For example, take a photo such as this one:
I exposed the image fairly well, but it lacks contrast. It also honestly lacks "life" as a result. Well, we've talked about adding contrast to the image but let's look at what starts to happen to this image when we do that:
First, let's darken the shadows:
Here, the shadows still have detail, but notice we didn't really add life to the image. The sky still looks flat. Our greens still look dull.
Let's try brightening the highlights:
Now we've got nice white clouds, but again the sky and greens look dull.
Let's try one of those magic contrast filters from CEP! Maybe a Tonal Contrast adjustment:
Our clouds and greens look a little better, but that sky sure doesn't want to budge does it? And the image still lacks "pop" that an HDR image would have. Which brings us to the question of how is HDR achieved?
Bracketing
Normally, HDR is something a photographer plans in advance. If you know you want to take an HDR photo, you really take at least 3 photos several stops apart from each other. This process is called bracketing your exposure. It existed long before HDR. Photographers used to do it to be sure they got a good shot on film.
For example, if you take 3 photos all 2 stops apart, you can cover a range of 10 stops instead of just 6:
Photo 1: 1,2,3,4,5,6
Photo 2: 3,4,5,6,7,8
Photo 3: 5,6,7,8,9,10
These 3 photos would then be combined on the computer (Photoshop has an HDR merge built in) and a photo with more "life" results.
Problems with HDR Bracketing
As you can imagine, movement is a huge issue for HDR. Even if the photographer uses a tripod anchored in concrete, the scenery can move causing problems with the photo merge. (Scenery like trees in the wind, water flowing in a river, that deer you were shooting runs away in the middle of the bracketing). However, if you have a relatively still scene and your slowest exposure is still fairly fast, this is the way to go.
Faking HDR
Suppose you just have 1 frame. Can you "fake" it? Sure! Will it be as good? No! But it's probably better than the image you have to start with!
Some sites will walk you through explanations of how to darken and lighten the image, change EXIF data and try to fake out Photoshop's HDR merge (or other merge software) into thinking you took 3 shots. Truth is, you have 6 stops of data. It doesn't matter if you have RAW or JPG -- if your sensor had to push data off both or either end of the histogram, it's gone! (Highlights are somewhat recoverable, but not enough to equal HDR). Darkening and lightening one image will never give you the 10 stop range that bracketing would have.
These sites do provide useful techniques. They do improve the dynamic range of a single shot. But we're trying to talk free and easy here!
Get to the FREE Action Already!
Ok, ok. So we can fake it! There are several actions around the 'net that do a decent job of faking HDR. One I'll recommend to you is PseudoHDR available for FREE here:
FREE Pseudo HDR Photoshop Action
Simply load the action and hit play with the image you want to edit already open. Play a bit with the 2 settings it requests from you. In general, you want high pixel adjustments on high resolution shots and significantly lower pixel adjustments on low res shots.
Here is the result from running PseudoHDR on my image. No other adjustments were made. Since the original is over 3,000 pixels on the longest side, I used a vignette of 150 pixels and a highpass of 25 pixels.
Not bad for about 15 seconds of "work" and $0 ... now is it? And keep in mind, we can mask and blend to our heart's content once the action is done. I just left it right out of the action for this discussion's sake.
Hope this has been helpful. If so, I'll continue to put FREE stuff up that impresses me.
Favorite FREE Photo Effects - HDR
Part of what you are seeing is due to the vignette that surrounds the image. Part of what you are seeing is an effect that could be duplicated by using a polarizer in front of the lens and finding the right angle to the sun.
