HDR Explained

HDR Explained

HDR is achieved by ‘Bracketing’ multiple shots, which each emphasise the different areas of light and then combine them into 1 ‘HDR’ image that then has the detail of highlights, lowlights and midtones.

What do I need for HDR?

1)It is a huge advantage if you have a camera with auto bracketing.If you don’t then you can manually change the exposure for each of the shots.

2)A tripod or something to rest the camera on is a must as you want the exact same image multiple times and so movement between shots will mess this up.If you haven’t got a tripod then a bean bag or even a jumper to rest the camera on can help.

3)Software such as Photoshop or Photomatix to create the HDR from your separate shots.

How do I take HDR photographs?

I ALWAYS use a tripod for HDR shots.I set my auto bracketing to 2/3 stop and take 3 shots of the scene.I then increase the bracketing to 1 stop and take another 3 shots (this is just to give me 2 options and effects when combining the photos later and is up to you to decide your preferred settings through trial and error).

If your taking your photos were there are moving subjects such as people of trees etc it is best to wait until the movement is at a minimum as this can cause ‘ghosting’ in the final image were you have the position of the moving object represented however many time a photo was taken (although Photomatix has an option to reduce this effect).

What to photograph in HDR?

My HDR set on Flickr, with various locations and subjects :)

  • Street Scenes

When I go out looking for a subject for an HDR image I look for a number of things.Colours are a great start, in the image below, which was taken in High Wycombe, the colours of the buildings and the lighting are really bought out by the HDR process.

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  • The Sky

Also keep an eye on the sky, a deep blue sky with the odd cloud gives a dramatic effect to any photo, combine this with a good foreground subject and your on to a winner.

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  • Sunsets

Sunsets are great for normal photography but if you use the HDR technique this gives a completely different effect.

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  • Water

When I first took three images of water I assumed that when I came to process them the 3 photos would be completely different due to the movement of the water surface.This is not the case however and it actually works pretty well (I still can’t get my head round how the position of the water surface is the same each time!)

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Creating an HDR image

Once you have downloaded your photos make sure you sort them into batches of the same scene so that you know which photos are to be combined.I always use 3 bracketed shots and so rename them in the first instance to A1, A2, A3, B1, B2, B3 and so on.

My preference is to create the HDR image in Photomatix and then put the finishing touches on in Photoshop.

Photomatix

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The 3 images above are the bracketed shots taken at 2/3 stop difference.  They were all at ISO 100 and F20 but the exposure times were 1/3sec, 1/10sec and 1/40sec.

To load these in Photomatix;

  1. Select ‘Generate HDR image‘ from the menu on the left of the screen…
  2. Next select ‘Browse‘ and then select the three (or more) images using ‘Ctrl’ and clicking on each of the images.  When you have them all selected click ‘Open’…..

You will then be presented with the  screen to show you what files you have selected and to allow you to add or remove some of the images if you wish, if you are happy with the images that you have selected, click ‘OK’……

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The ‘Generate HDR – Options‘ window allows you to the following options before processing the image;

  1. Align source images – If you feel that there could have been movement between the shots taken then you can choose this option to allow Photomatix to attempt to align the images.  The two methods it will attempt to do this using (which you can choose) are by correcting horizontal and vertical shifts and trying to match the features within the image (I usually choose this option if any).  Choosing to align the images will mean that the programme will take a bit longer to create the image.
  2. Attempt to reduce ghosting artifacts – if there is something moving in the image, such as a person or a tree etc, the this option will tell Photomatix to try and reduce the ‘ghosting’ effect where the movement is captured in each image and results in three seperate instances of that person or tree (for example).
  3. Take tone curve of colour profile – this option will mean that Photomatix will use the colour profile from the source image.  This is usually the best option when the images have been taken with a DSLR camera or have been converted from RAW files. (I usually leave this option checked).
  4. Attempt to reverse-engineer tone curve applied – when the images are from scanned films or taken with a compact camera/point and shoot camera, it may be worthwhile to check this option (but I never use this option).

Once you are happy with the options you have selected then click ‘OK‘…..

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Once Photomatix has churned through the aligning and reduction in ghosting etc then you will see the beginnings of an HDR image displayed.  Don’t worry if it doesn’t look particularly ‘HDRish’ yet, as this is where the fun starts…..

Click on the ‘Tone mapping’ button on the left of the screen and Photomatix will then presen you with, what should hopefully be, a more ‘HDRish’ image which you can then start to adjust using the various options in the menu that appears on the left.

On the ‘Details Enhancer‘ tab you have the following options;

Strength – This is the overall effect of the HDR process, I usually leave this set to ’100%’ as you can usually adjust the image using the other options without using this one.

Colour Saturation - Pretty obvious really, this is the amount of colour in the image, this is your call!

Light Smoothing - This option controls the contrast variation in the image, normally I use the second or third check bow from the left as the image usually looks over the top if the first one is selected.  The below image shows the differences that changing the light smoothing can have (‘Min’ to ‘Max’)

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Luminosity – This slider brighten shadows the higher you select and also increases the contrast of the image.

Next you can move onto the individual controls for the image…..

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  • White Point – This increases the brightness of the highlights on the image.
  • Black Point – This increase the effects of shadows and contrast on the image.
  • Gamma – This brightens or darkesn the image on a global scale.
  • Temperature – This increases the temperature of the image, the higher you go, the more reddish the image, the lower the more blueish.
  • Saturation Highlights – This increases the colour in the highlights of the image.
  • Saturation Shadows – This increases the colour in the shadows/lowlights of the image
  • Micro Contrast – This option extentuates the contrast between the highlights and the shadows of the image.
  • Micro Smoothing - This option smoothes the image globally and, in my opinion, reduces the effect of the HDR process if used too much.
  • Highlights Smoothing – This option just smooths the highlights of the image, it can help to counter the ‘haloing’ effect around objects on the image but can also ‘wash out’ the highlights if used too much.
  • Shadows Smoothing -  This option just smooths the lowlights and shadows of the image.
  • Shadows Clipping – This increases the the density of shadows, where you might be able to see other details within the shadows with this set to a low value, if you increase this the shadows will be more dark and not contain any detail.

The best way to get used to these controls is too muck about with them until you are happy with the outcome.  Once you are, click on ‘Process’….

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Once you have the finished image select ‘File/Save As’ to save your image.  At this point I ormally open the image in Photoshop and muck abou with the curves etc.

Resources;

Some examples of HDR

By MorBCN

By MorBCN

 

By Robert Scott Photography.ca

By Robert Scott Photography.ca

 

By alexkess

By alexkess

 

By Andrew Stawarz

By Andrew Stawarz

 

By Bring back Buck

By Bring back Buck

 

By left-hand

By left-hand

 

By Wunderlich Photography

By Wunderlich Photography

 

By bmooneyatwork

By bmooneyatwork

 

By EugeniusD80

By EugeniusD80

 

By Lone Primate

By Lone Primate

Golden Rule – DON’T OVERDO HDR! – an overdone image that looks like a comic drawing looks  just don’t work (in my opinion).

Written by Barry Chignell

I believe that advice should be free, with this in mind FPR contains over 600 photography articles covering all areas of the photography world. From wedding photography to HDR and from interviews from retailers to pro photographers. I am always interested to hear from anyone in the profession regarding new and exciting ideas and ventures and am happy to help photographers publicise their work. If you would like to discuss your photography and how FPR can help, email me at bchignell@gmail.com.

16 Comments

  1. Omnipresence

    There has been a glut of badly tone-mapped photos flooding the internet over the past few years under the guise of being called “HDR” – you have to make sure that when you use the tone-mapping options that you seek to blend the exposure values to result in a “natural to the eye” look, and not try to go in for the more dramatic or over the top tone-mapped settings.

    Enfuse is another alternative to Photomatix or Photoshop’s photomerge functions.
    http://wiki.panotools.org/Enfuse
    It does not really have an easy to use tone-mapping option, though through some trial and error you can bring out some details better than others using the available controls. Overall Enfuse is great for a clear, straightforward merged image without the added grain and noise.

    All too often I’ve seen HDR photos that have a surreal, or overdone look to them which on the whole seems to have created a negative opinion on what HDR can actually do for your shots according to the blogosphere.

    HDR works really well under certain specific circumstances – low light shots (twilight or dawn), interiors when you want the inside and view out the windows equally exposed, looking into the sun (sunsets or sunrises) when you want your foreground equally exposed to the colors in the sky.

    HDR does not work so well on moving scenes – crowds, traffic, wildlife – due to the sequential shooting of auto or manual bracketing.

  2. Beth Hastings

    It appears that some of the images in your “HDR explained” tutorial are missing (halfway down the page.)

  3. Myong Ryen

    Excellent article and easy to understand explanation. How do I go about getting permission to post part of the article in my upcoming newsletter? Giving proper credit to you the author and link to the site would not be a problem.

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