HDR processing

Back when I made my first post about HDR, I didn’t really know all that much about it, but I’d like to think I’ve improved since then, so I’d like to give you a run-down of some ways I do High Dynamic Range photography.

From Time to Time

When you take a single photo, the in camera metering system tries to find the best way to expose for middle gray. This means that unless some post processing goes on or you change your exposure down or up a few stops, you might not get all the color or detail in either the shadows or the highlights. HDR is one solution to this.

True HDR is the combination of bracketed exposures to get all the shadows and highlights present in a scene. Personally, I prefer to make 5 separate exposures 0EV, -1EV, -2EV, +1EV,+2EV. This is achieved by increasing or decreasing the camera’s shutterspeed while mounted to a tripod. Other ways to change exposure are ISO, and F-Stops, neither of which are recommended to change the exposure of this particular shot, because the shots will later be blended together. Changing the F-Stops would change the plane of focus, and ISO would change the amount of noise, we want both to stay constant throughout this procedure, so only shutter speed will be changed. So pick an F-Stop and an ISO (which you’ll want to keep as low as possible so there will be the least amount of noise in the final tonemapped blend) and shoot your five shots. RAWs are preferable, this way the programs we use will have the maximum amount of data to work with and blend together.

Lakeside

HDR can also look realistic (creating a photo that is closer to how your eyes comprehend the shadows and highlights of a scene than would normally be possible with just one exposure in some cases) like the photo above, or it can have some odd qualities to it that you might enjoy, such as the flower above or the scene below.

Into The Sun

There’s a multitude of programs out there to use for blending together HDR shots, photoshop is a good candidate, but the most popular one is called Photomatix. This program was built specifically for HDR and exposure blending, I would highly recommend grabbing a copy of it if possible.

Open or drag your 5 shots into the window and click Generate HDR. If you have one or more shots with the same exposure value, then it will ask you to specify how many stops apart the pictures are that you dragged into it. You can choose whether you want it to crop the edges for you, whether you want it to attempt to reduce ghosting or not (which occurrs if there’s trees that moved from one exposure to the next, or people moving around, it does a pretty good job of it most times, but obviously there will be visible ghosting if there’s an object on one side of the shot that gets moved a few feet over in the next) and you can also tell it what white balance you want, along with noise reduction and various other things.

The next thing you’ll see once it’s done with all of that is the un tonemapped 32bit file of all your exposures blended together, which includes all information that’s between those files. You can’t save it like this and be done, you have to tonemap that file so your computer has a finite set of values for the different parts of the end photo instead of the 32bit gigantic glob of potential that was originally generated.

You can either use the Tone Compressor, or the Details Enhancer. Sometimes it really just depends on what you want your photo to look like in the end, there’s really no right or wrong way to do it.

Since the preview image changes while you move the sliders, you can just experiment to get something that suites your fancy. Of course, you may or may not want to touch your image up in photoshop. Atleast, if you plan to post it on the internet, you should convert it down to an 8bit image instead of 16bits, because most image uploading websites dont take kindly to 36Mb Tiff images.

If you have any questions feel free to ask. I’ll probably give you a rundown of some of the photoshop plugins I enjoy using in the near future, a few of which were used to polish off the image of the flower up above.

Until then! Go shoot yourself some HDR.

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