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  1. #1
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    Guide to HDR Photography

    High Dynamic Range Photography

    A long time ago I promissed some people that I would write a HDR tutorial. Now I finally did it. I hope you will enjoy it and can use it when creating HDRs

    What is High Dynamic Range Photography?
    In some scenes, it is very hard to find the right exposure. The exposure you chose is often a compromise. Either the sky looks great and the foreground is too dark, or the foreground is exposed properly but the sky is completely blown out.

    In such scenes, High Dynamic Range photography (HDR) can help out. HDR photography is a technique where you blend various exposures of the same scene to get the whole image exposed properly.

    This guide will go through the process of creating a High Dynamic range picture step by step. If you have any questions, feel free to ask them. In the guide, the following software will be used: Adobe Photoshop CS, Photomatix, and PTGUI.

    Step 1: Taking the pictures
    There are multiple ways to take the source pictures of a HDR. The one thing that all approaches have in common is that the pictures used have a different exposure and that the different exposures cover the whole range of the scene.

    Take a look at the following example. I took three pictures, they are all two stops apart.

    Attachment 25855

    The first picture is two stops underexposed. You can clearly see in the histogram that most of the data is on the left side of the histogram. A part of the scene is even cut of the histogram. This means that the detail in some parts of the picture is lost. However, you can also see that there are no highlights cut of. Therefore this picture covers the highlight of the scene nicely.

    The third picture is two stops overexposed. Here you can clearly see that the highlights are all blown out. However, the dark parts of the picture are properly exposed. This picture covers the shadows of the scene.

    The middle picture is right in between the two. This picture covers the mid-tones of the scene.

    You can take as many different exposures as you like. I took only three here, but you can also take pictures at steps of 1 f-stop, meaning you would have 5 pictures. However, I find that more pictures does not necessarily give better results. In fact, fewer pictures means that the time taken between all the shots is minimal and this often gives better results with the sky.

    The best way to take the pictures is by using a tripod and the bracketing function of the camera. If you are too lazy to use a tripod (like me) you can also align the images later (see step 2). If your camera does not have bracketing, you can also adjust the exposure manually. You need to do this real quick, though, because cloud movement between the shots can have a drastic effect on the result.

    Personally, I always take the source files of the HDR without a tripod but with the bracketing function. I set the exposure difference at 2 stops and take three images. Most of the time this covers the dynamic range of a scene.

    One thing to keep in mind, is that you must always keep the aperture constant during the shoot. Changing the aperture will change the depth of field, and may therefore cause difficulty with aligning the images.

    Step 2: Aligning the images
    Photomatix, the software that we will be using to create a HDR, can align images. It does that by rotating and shifting the pictures. When you use a tripod, this is often sufficient. In that case you can skip to step 3.

    When you are not using a tripod, the difference between the shots will be greater. In that case, Photomatix often cannot align the pictures. This especially occurs if the pictures were taken with a wide angle lens. With such a lens, minute changes to the way the camera is pointed has quite a big effect on the perspective. Photomatix cannot correct this and therefore cannot align the image.

    PTGui is a panorama program. This program is a lot more powerful in aligning images, since it can warp them so that they will match perfectly.

    The following needs to be done:
    - Load the images into PTGui
    - Set the lens focal length and the crop factor (if this is not done for you)
    - Generate the control points
    - Check the result with the panorama viewer
    - If you like the result, the ‘panorama’ can be created
    - When saving the panorama make sure that you select the maximum picture
    size available and that you export each layer separately. You should not
    save the result as a blended panorama.

    Attachment 25856


    The result of this step is that you have a couple of perfectly aligned images which can be used to create a HDR in Photomatix.

    Step 3: Creating a HDR in Photomatix:
    Now we can start creating the HDR file in Photomatix. To start, click on the HDR menu and select Generate. You will get the following screen. Here you can select which files to import:

    Attachment 25860

    If you did step 2, load the files created with PTGui. If not, just load the original image files.

    Original image files will have the EXIF still attached, which means that Photomatix will automatically detect the exposure of the images. With PTGui files you will have to set the exposure values manually. In this case we fill in -2 for the dark shot (2 stops underexposed), 0 for the middle shot, and 2 for the bright shot (2 steps overexposed):

    Attachment 25861

    Next you will get the following screen:

    Attachment 25862

    If you aligned your images using PTGui, always keep the box “Attempt to align images” unchecked. If you took the images with at tripod you can check this box. I always chose “Attempt to calculate tone curve applied” but I think you can also select one of the other options. I tried the different modes several times and didn’t see much difference between the results.

    Photmatix will now create the HDR. If you let it align the images, this will take a bit longer. The result will look terrible. Don’t be afraid, though. It will get better in the next step.

    Step 4: Tone Mapping
    Tone mapping is by far the most important step of the process. The tone mapping can be started by going to the HDR menu and selecting Tone Mapping. You will get the following screen:

    Attachment 25863

    Here is a small list of the things you can set and the result these things will have:

    Strength: I generally set this at 80 or 90. Be careful not to set this too high, it may make the result look unrealistic. Even at medium settings, the program will still enhance the details. The strenght must be set low if the light smoothing is reduced (see below).

    Colour Saturation: It is default, and you can keep it that way. The program is not very consistent when it comes to saturation. It often looks different than the preview. It is therefore easier to set this later in Photoshop.

    Light smoothing: This must generally be set at the highest setting. Setting this lower will only give good results if you severly reduce the Strength of the tonemapping. If you set this slider in the middle, the strength must be lower than 50%. One step lower will force you to reduce the strength below 30%.

    Luminosity: The way this has to be set varies from image to image. Most of the time, you can keep this in the center. Sometimes, moving it to the right or left will improve the contrast.

    Micro Smoothing: Setting this high will reduce the noise, but also the local contrast. I generally keep this at 3 or 4. I get little noise that way, but retain much of the local contrast.

    White Clip and Black Clip: These can be used to enhance the contrast. Setting them higher will give a higher contrast. Be careful, though. Setting this higher will make you loose detail in the highlights or shadows. I generally keep the sliders no more than 3 or 4 clicks from the left.

    You can save the settings. However, different scenes will often require different settings, so there is not much point in doing this.

    Photmatix also has a Tone Compressor mode in the Tone Mapping screen. I find that this mode will generally give a lot less interesting results. The results are a lot more dull. Therefore, I will not discus that mode now.

    If your done, click OK and check the result. Sometimes it looks a lot different than in the preview. If that is the case, you can undo the tonemapping (HDR >> Undo Tone Mapping) and try again with different settings, until you are happy.
    After that, save the image and exit.

    Step 5: Finishing the HDR
    A HDR made in Photmatix often requires some work in Photoshop. Here are a couple of things you can do to make it better:
    - Levels: Using levels, you can shift the white or black point a little. In that
    way you can give the scene more contrast.
    - Curves: Using curves, you can make the shadows a bit brighter, darken the
    highlights, or increase the contrast. As a rule of thumb, you can say that
    the steeper the curve, the higher the contrast is. With careful use, you can
    raise the contrast without destroying any of the highlights.
    - Unsharp Mask: The unsharp mask can be used in two way. First, if your
    scene looks a bit dull, you can raise the local contrast to make it more
    dramatic. This can be done by selecting values such as (20, 50, 0) – a high
    radius with a low strength. Secondly, you can sharpen the picture with
    values such as (80, 1, 0) – high strength with a small radius.
    - Hue/Saturation: Using this tool you can adjust the saturation of the result
    to your liking and reduce colour casts resulting from the process. This last
    thing can also be done using the colour balance tool.
    - Burn tool: If you raised the white clip in Photomatix too high, you can
    sometimes recover this a little using the burn tool. This is sometimes easier
    then setting it lower in Photomatix, because with the white clip at very low
    values, Photomatix will output a very dull file requiring lots of work in
    Photoshop.

    Sometimes it is hard to get the colours right. In that case, you can also convert the image to black and white. HDR images will often make amazing black and whites. This can of course also be done with HDRs for which you did get the colour right.

    Step 6: The Result
    If you are happy with the way it looks in Photoshop, you are finally finished. Here’s the result I got with the example image:

    Attachment 25864

    Note that many people have different tastes when it comes to HDR. Some like realistic results, while others like the crazy colours and contrast some HDRs have. There is no right or wrong here. Just experiment and try to find what you like best.

    Some more notes

    HDRs with a single RAW file
    You can create HDRs with a single RAW file. A Raw file has a bit more latitude than a JPEG file, which can be used for the HDR. However, more often than not, the single RAW file does not cover the entire range, which will cause weak results. Also, this method may result in a lot of noise in the shadows. Finally, you can often achieve the same results with a RAW converter. Nikon Capture NX has D-Lighting and control point with which you can do almost the same thing.
    In any case, it is not necessary to create different exposures. Photomatix accepts raw files and can Tone Map them without further action. It may give a colour cast to the picture, but that can easily be fixed in photoshop.

    HDRs with a single JPEG file
    This cannot be done. A JPEG has not enough dynamic range. Creating different exposures will not help; details lost in highlights or shadows cannot be recovered. Instead of trying this, you can also play around with tools like the shadow-highlight tool, curves and the unsharp mask. This will do a much better job in raising shadows, darkening highlights and enhancing details.

    HDRs without Photomatix
    There are other programs to create HDRs. I have not tried any of them, but I suppose decent results can be achieved with these programs too. I have tried the Photoshop plug-in, but I find that Photomatix works a lot easier.

    DSLRs vs. Compacts
    You can create HDRs with any type of camera, as long as you can set the exposure manually. Most Compact cameras do not have bracketing, which might make it more difficult, but it can be done.

    Using TIFF
    If you shoot RAW, you can deserve some of the extra dynamic range by working in 16 bits TIFF throughout the process. This will theoretically give better results. All programs used here, support 16 bit TIFF files. However, using TIFF will slow the process down enormously and it will require a lot of memory. Personally I find that the benefits of using TIFF are too small, so I work in JPEG all through the process.
    Last edited by Prospero; 07-05-2007 at 04:57 PM.
    Nikon D-50
    // Nikkor 70-300 f/4-5.6 VR // Nikkor 50 mm f/1.8
    // Sigma 17-70 f/2.8-4.5 ...// Nikon SB-600
    // Sigma 10-20 f/4-5.6......// Nikon Series E 135 mm f/2.8
    // Kiron 105 f/2.8 Macro....// Manfrotto 190XPROB + 488RC4
    // Nikkor 35 f/1.8..........// Sigma 500 mm f/8

    My website: http://www.dennisdolkens.nl

  2. #2
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    Hi Prospero... here is a semi-DRI/HDR.
    (DRI = Dynamic Range Increase)
    The top photo is the standard RAW developed photo.
    The 2nd one is the result of developing the RAW at -2EV, 0EV and +2EV, then running them through Photomatix Pro. No alignment needed here, of course.
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  3. #3
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    Nice picture, Coldy. The treatment with photomatix definitly improves the picture by strengthening the autumn atmosphere.

    In these situations I don't use HDR most of the time, though. I use Nikon Capture NX which has a tool called D-Lighting. Using this tool, you can brighten the shadows and darken the highlights.
    The tool uses the extra dynamic range of the RAW file, and therefore gives great results. It is also a lot quicker than creating several versions and blending those.

    By the way, did you try to import the raw file with Photomatix yet? I found that it can also tone map a single raw file, so that there is no need to create multiple exposures.
    Nikon D-50
    // Nikkor 70-300 f/4-5.6 VR // Nikkor 50 mm f/1.8
    // Sigma 17-70 f/2.8-4.5 ...// Nikon SB-600
    // Sigma 10-20 f/4-5.6......// Nikon Series E 135 mm f/2.8
    // Kiron 105 f/2.8 Macro....// Manfrotto 190XPROB + 488RC4
    // Nikkor 35 f/1.8..........// Sigma 500 mm f/8

    My website: http://www.dennisdolkens.nl

  4. #4
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    When you use 3 RAW-developed "exposures", you have the ability to selectively filter noise, and you can determine the whitebalance in teh RAW convertor. So it does have at least these two advantages...
    Last edited by coldrain; 07-02-2007 at 07:42 AM.
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  5. #5
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    one of the best tutorials i have ever read.
    thanks for taking the time m8. faved for sure.
    D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75
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  6. #6
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    Quote Originally Posted by Rooz View Post
    one of the best tutorials i have ever read.
    thanks for taking the time m8. faved for sure.
    Thanks Rooz. I am glad you like it.
    Nikon D-50
    // Nikkor 70-300 f/4-5.6 VR // Nikkor 50 mm f/1.8
    // Sigma 17-70 f/2.8-4.5 ...// Nikon SB-600
    // Sigma 10-20 f/4-5.6......// Nikon Series E 135 mm f/2.8
    // Kiron 105 f/2.8 Macro....// Manfrotto 190XPROB + 488RC4
    // Nikkor 35 f/1.8..........// Sigma 500 mm f/8

    My website: http://www.dennisdolkens.nl

  7. #7
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    Quote Originally Posted by Rooz View Post
    one of the best tutorials i have ever read.
    thanks for taking the time m8. faved for sure.
    Yup! Love to see people putting so much effort into helping out. Cheers Hopefully I can do the samefor someone in need one day

  8. #8
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    Thank you Prospero for this great tutorial, I found it very informative indeed, up untill now I've been using HiTech graduated neutral density filters and will give Photomatix a try in the near future.

    Sony DSC-F707 using 2 x HiTech GND filters:

    Last edited by Wirraway; 07-13-2007 at 02:12 AM.
    -Ian

    Sony DSC-F707
    Sony DSC-H5
    Sony DSC-W100

  9. #9
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    one of the best tutorials on HDR!

    i saved the full tutorial, and am going thru it, step by step, as if a text book.

    i have not seen a more lucid treatment of the subject, with examples , even in the trade magazines.

    Prospero, many thanks for it.

  10. #10
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    Beautiful image, Wirraway.

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