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I hope you found this "How-To' of some value. I also tried to give it some sense of the "Why?" |
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I thought I'd show the processes I followed in building the above photo, which is the same (though further enhanced) as the one in a previous tabblo - Brooklyn Sunsets. |
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Using reduced opacity, you can see in the image on the right how the layers no longer overlap perfectly. It's also easy to see the area where they do overlap. Cropping to that size is straightforward and that's what I did.
At this point the images, in layers, are aligned and of equal, though very slightly reduced, size. Each layer has to be separately saved as a 16-bit tif file so it can be correctly processed by the HDR program - Photomatix.
Just a reminder: Make sure you set the opacity back to 100% for the layers before you save them. The saved images will be somewhat "see-thru" otherwise.
We were forced to take a side trip to fix a problem but we're back on the right route now. |


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It started with a casual bike ride to the boardwalk in Coney Island. This is a visually interesting place and perhaps unusually so during the off season when the crowds are gone. The sun was setting and the sky was a maze of orange tinged clouds and bright streaks against a blue background. So I stopped and set up to take some pictures. I knew that I wouldn't be able to capture the mood of the scene with a straight forward single shot. The light range was too great. So I decided to shoot a series of images for a high dynamic range photo. This is a method to capture the full tonal range of difficult photographic situations, such as a bright sky along with a foreground lit by late afternoon skylight. |


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I use the bicycle as a quick and convenient tripod, dropping the kick stand and clamping the camera to the top post. Unfortunately it was a very windy day. That's the main reason there were so few people around. It was chilly but mainly it felt cold because of the strong wind. In shooting the three images needed for the high dynamic range exposure bracketed series I had to hold the bike to keep it from moving and shaking in the wind. Usually this is a bad idea since a hand hold is not a steady force. But there was no choice. I'd have to give it a try. I shot a few series of images. It's fairly automatic on the camera once it's set up for bracketing. Set the self-timer to shoot and the three pictures fire off automatically, each two stops different in shutter speed.
You can see the series on the left. |


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Mid-tone, two stops under exposed and two stops over-exposed.
I think you can get some idea of why I didn't think the scene could be properly captured in a single exposure. Also perhaps why I stopped to take a picture. It was a pretty sunset right on the end of the boardwalk.
So where do we go from here? |


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I used a program called Photomatix to generate the composite high dynamic range (HDR) image from the exposure bracketed series. There are other HDR programs and Photoshop, the standard of image editors, can also process HDR images. I've used Photomatix in the past and it is fairly easy to use and the results are usually pretty good.
First thing you have to do, after starting the program, is read in the bracketed series of images. |
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Choose "Generate" |


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"Browse" to find the three image files. |
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"OK" to load them in for processing. |




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You may have noticed that these are "tif" files. They should be "RAW" files, the native format of the camera. I ran into a problem which I'll soon describe and had to use tif files I created from the RAW files the camera produced.
Because they were tif files the exposure information which is usually part of the image file wasn't there. So Photomatix had to ask what the exposure value differences were between the files. I set the spacing entry to "2" and the boxes next to the image icons changed to correctly match the image brightnesses. |


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After clicking "OK" on the option menu the program merges the bracketed series of images. |


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After the image is merged Photomatix displays a pre-tone mapped view of the result. It usually looks pretty bad, but it hasn't been tone mapped, so there's nothing to worry about.
Except in this case.
Notice the magnified view, which is also part of this screen view of the merged images. There are ghost images of the tower. The original images are not properly registered. The camera-bike combination moved with the wind while the pictures were being shot.
That's a problem. There's no way to get a good result without proper alignment. I tried the "Align" option I described previously. No good.
What's to be done now? |
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That's where the "tif" files came in from above. I couldn't use "RAW," the preferred form from the camera, because the tools for RAW processing don't do the sort of manipulations that I needed to manually align the pictures. At least not that I know of. So I had to process the RAW images in an image editor where I could align the images and then save them in a standard format that could handle the required 16-bit format needed. That's "tif." "16-bit" just means extra shades in the colors and tones, which are needed when you're handling wide tonal ranges.
So it's time to use an image editor to work on the misaligned RAW image files. That's Photoshop and its "Camera RAW" program. |


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When you load a RAW image into Camera RAW the program automatically tries to make the picture look good. Usually that's something of a help in the adjustment process but with an exposure bracketed series that's a problem. The differences in exposure in the series will be masked by the automatic adjustment and basically screw everything up. So you have to turn off all the "Auto" settings. Uncheck them all.
Other changes can be made but any change should be applied exactly the same way to each image in the series. Say if you correct the color balance ("Temperature"), the same correction must be applied to all the images in the series. For me, the lens I was using has some color aberration. I could see it in the lamp post on the left. It was fringed with green on one side and red on the other. Camera RAW can actually correct for that and I did the correction - and did the exact same fix on all three images in the series.
From Camera RAW the images get handed off to Photoshop for further processing. Fun. Fun. Fun, and no T-Bird in sight. |


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So I've got three images now that are slightly out of register - alignment. How do I fix that?
First I load one of them and use it as the base. Then I load the next and copy it onto the base image as a layer on top of it. It's easy to see how the images are misaligned when that's done because you can instantly turn off and on the visibility of a layer. When that's done at full resolution the jump in position of objects in the image is obvious. Do the same for the third image and copy it as another layer on top of the prior two.
Here on the right you can see the three images layered on top of each other. I renamed the layers to indicate their original brightness. The opacity was set below 100% so the ghosting could be seen between the layers. The "background" layer is the same as the second one here. |


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To manually align the layers they have to be moved a bit with respect to each other. That means there has to be some room to move them around. To get this room I increased the size of the "Canvas." That adds some border room around the existing image area.
You can see this on the left with the slight border seen in the icon images in the layer stack.
I then used the editor's "Move" tool to individually move the layers, slightly, with respect to each other, until the tower in the image was perfectly aligned, layer to layer, image to image.
But this meant that the image borders would not line up any more. I'd have to cut off the excess from all the images. |




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Using Photomatix as described previously, but with the corrected tif files rather than the misaligned RAW files we get back to the initial merge display screen with the magnifier box. Notice that the alignment is now good.
Whew! That was a lot to do to get back to the start of the process.
Actually this didn't take that long. It certainly took a lot longer to type out how it was done than to do it. The problem was quickly seen and the solution was apparent and quickly implemented. It probably took you longer to read about it than it took to fix the problem.
We're now ready for the tone mapping - the process of making the image look like what we remember, or better. |


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Wow! That's better!
Actually, since Photomatix saves the last settings that were used, this is the final result after all the adjustments I made to get the look I thought best. Usually the first view isn't the best and playing with the various adjustments is what the program is all about.
Anyway, this is what it looks like in color. It's more like what it felt like at the time. We never really get a sense of blown out sky or daylight shadows so deep they have no details visible. Sure, it's beyond "real." Super saturated colors and extra contrast, but I can live with that and if I want to get it looking better, then this is just a starting point for further enhancement. |


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A bigger view. I'm not that happy with this result. It's lost fine shadow detail. I had some problems with the computer I use to connect to the Internet so the original processing of these images was done on a backup setup where the images look slightly brighter. That made the shadows look better. It was when I transferred them to the Internet computer that they looked a bit too dark and contrasty. But I had no image editor installed on the still "under construction" Internet computer to fix the problems. |
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As I've mentioned, though describing what I've done to this point makes it seem like a lot of work, it was actually fairly straight forward, even with the alignment problem. It didn't take that long to do since the choices and options are somewhat set.
It's when you look at an image and start to think about what you might try to make it look a little better that things start to slow down. Adjust some here. Fix something there. Make that brighter. Give that more snap. It goes on and on, especially when each of those tweaks does improve the image. But that's what making pictures is all about. |
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In looking at the image I thought it was an OK sunset. Something didn't quite "make it" though. The sunset is a beautiful wonder of nature. That fit fine with the left side beach scene but it doesn't work that well with the wall mural on the right or the shuttered shops further in the distance. This is Coney Island. Its garish quality is not only traditional, it's historic. What could I do to make the beauty of the natural sunset better relate to the carnival world of Coney Island, off season?
Black and White. |
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I made the B&W version directly from within Photomatix. I could have worked with the color output and done the conversion to monochrome in Photoshop. That might have been better but because of the two computer setup problem, I kept it simpler.
Since then I've done some fix-ups on the B&W version from the "Brooklyn Sunsets" tabblo. The image at the top of this tabblo has much more shadow detail - the "texture" of the scene. The sun is also clearly defined as a half circle at the end of the boardwalk.
You don't see it?
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