Ok, so today I decided to snag the Cannon G9 (very nice point and shoot) from work and snap some HDR photos. For those of you that are unfamiliar with HDR Photography here is a little plot synopsis:
HDR stands for High Dynamic Range. When a camera takes a photograph it is limited by the amount of color that the lens can see. The human eye can see a wider range of color. Sometimes you will look at a scene that to the eye is beautiful but when you take a photograph it doesn’t capture the same feel that you get when you look at it. Usually this is because of a high contrast between light and dark in the image. When you capture a really bright image the darkest areas turn black so that you can see the detail in the lighter area. Also when you capture a dark image the lighter areas turn white and get blown out so that you can see the detail in the dark area. Now the images I worked with in this example were not that high of contrast but I wanted a reason to play with the technique so I went out shooting… maybe later I can get some better examples of high contrast images. In the meantime you can see how just a regular photo can be enhanced with HDR technique.
Ok so now that you know what HDR is lets overview how HDR works. This is where I get all technical and have people stare at me questioningly so you might want to have a general idea of how photography works before attempting HDR, but I will try to explain as best I can….
When a camera takes a picture there are a few things that effect how that image will look once it is captured. The ISO, the shutter speed and the F-stop or aperture. ISO is how sensitive a digital camera is to light, the higher the ISO the less light needed to capture the image. The shutter speed works with the aperture to control the amount of light that is let into the lens and also how much light is allowed in. For HDR I recommend using a low ISO setting, I used 100. Now the idea of HDR is that you take a series of pictures that vary in contrast. To do this you will need to learn how to use the bracketing on your camera (I’m covering the technique in this blog NOT how to use your own personal camera so go read the manual or do a google search, you’ll figure it out) What Bracketing will allow you to do is shoot a series of 3 pictures but will automatically adjust your F-stop (aperture) up and down either 1 or 2 clicks. Now you want the shutter speed to remain the same when you do this so set your camera to Aperture Priority mode (this allows you to change your F-stop without changing your shutter speed) Then set your camera on a tripod (very important step because the series of pictures your going to shoot need to be the same)
Ok I’m sure if your an amateur everything I just said probably sounded like a foreign language but I’m really hoping you can grasp the basic concept…
When you take a picture you have a series of shots that vary in the amount of light allowed into the lens from a dark picture to a light and blown out picture and one F-stop click in between. What I did was first meter the scene and find the optimal aperture setting (I think it was 4.5) and then set the camera to aperture priority mode. I then set the bracketing to take a series of 3 shots one click above and one click below this setting. Then I took the picture. After that I was very careful not to bump the camera or move it at all and selected the 2 click setting in the bracketing mode and took another series of 3 photos. This left me with a series of 6 photos. 2 of these were the same but it also gave me both -1, -2, +1, +2 clicks on the F-stop. This ensures that I captured the full range of color and detail throughout the photograph. If I needed to capture a wider range I would just manually change the F-stop higher and shoot again, just be very careful not to move the camera or the tripod at all.
Ok now that I have all these images saved in the camera I have to put them all together. This is where some really slick software comes into play called Photomatix When you combine these images in Photomatix it creates a 32bit HDR Image that you can then save and import into Photoshop. Now when you install Photomatix make sure you also install the Photoshop plug-in because it is going to come in very handy in tweaking your HDR image. Once the image is in Photoshop you can then run the Filter>Photomatix>Tone Mapping and tweak your image to your taste. I’m not going to go into detail on how to tweak the image but if you just play around with the sliders you should be able to figure it out. One thing people tend to do with HDR images (and this is really easy to do) is make them look very cartoony and unrealistic. So be careful you don’t make your image too fake looking, unless thats the effect your going for. The best HDR Images I have seen have very subtle Tone Mapping tweaks to bring out the color to maintain realism in the image. Now before you start playing with your image more in Photoshop you need to turn it from a giant 32bit image down to a workable 8bit image. You can do this by clicking Image>Mode>8Bits/Channels. Now you can play around with any other photoshop filters of effects that you like.
thats a lot of information to cram into one little blog! I hope you got something out of that! If you have any questions feel free to leave them in the comments, I will answer them as best I can!