HDR Tutorial
I receive a lot of emails from fellow flickerites about my processing workflow on my HDR images, so I have decided to put together this little tutorial. This is the 1st of 4 tutorials I am creating, detailing the main processes that can/could be undertaken with different types of HDR imagery ranging from interiors, cityscapes, architecture and landscapes.
This is by no means a set workflow on settings or so. Different images will require different settings and as an individual, you will all have your own personal tastes on how you want an image to look.
On a personal level, my own technique is always evolving as I love to experiment with each image. Sometimes I go for the realistic look, whilst other times they may be a tad overdone.
Recently as I have experimented more, I have been more inclined to go for the realistic approach. (depends on the mood I guess...sometimes I feel like going crazy with an image)
I hope this tutorial helps those who are already dabbling in HDR and also those who are starting out with it. Please feel free to use it and pass it on to anyone else you may think be interested.
Step 1 - Taking the image
When I first started off using my DSLR, I knew diddly squat about camera settings, auto-bracketing, manual mode etc... Experimenting with different settings, looking at various tips and tutorials have improved my knowledge vastly on this.
So here we go then ....Firstly there are two main ways to create the source images needed for HDR.
- Autobracketing - One raw image
Autobracketing:
Most DSLR camera's have the ability to bracket multiple exposures. This is simply a way to tell the camera to take several shots in quick succession, each at different exposures. For example, in this image a -2, 0, +2 setting was used to take three shots. When deciding on how many auto-bracketing exposures to use, you will need to consider the contrast range of the scene. If there is a higher contrast range, consider using a wider bracket setting. Now this may not be possible on some cameras. My own Canon 400D only has the ability to bracket 3 shots, but some cameras are able to go as high as nine. Normally 3 exposures are suffice for me when shooting in interior locations, such as churches and other buildings. When I do need more than 3 exposures, I normally take auto-bracketing off in Aperture Priority mode and fire out 5 or more shots by manually changing the shutter speed each time.
One RAW image:
The other way to produce the 3 shots needed is to take 1 photo and adjust it in a RAW editor such as Lightroom, Aperture or any other one you may use. The main advantage with this is that you can produce a HDR shot with moving subjects such as cars and people. The downside from experience is that if an image contains dark shadows, the exposure adjusting followed by the HDR process has a tendency to create a lot of noise. The other thing that is debated quite often is that by taking 1 raw image, it doesn't truly capture the full dynamic data range of a scene.
Camera Settings
-Shoot in RAW - it allows you to capture more dynamic range data than using JPEGs.
-Use a tripod. In some places this can be difficult, especially in churches. Alternatively, try and find some kind of ledge, bench, stack of books or take up an awkward stance and take the image handheld.
-Use Aperture Priority mode on your camera. As you will be combining several images into one, you don’t want your Depth of Field (DOF) to change between shots, as the final image will appear all out of focus.
-Keep the ISO setting to the minimum. The higher the ISO setting, the more noise it will generate. I try to keep mine at 100 whenever I can.
Step 2 - Adobe Lightroom
I use a number of different software applications within my workflow.
Adobe Lightroom - Great piece of software. Makes sorting and managing images a piece of cake. You can download a trial here.
Photomatix Pro - Allows you to create a HDR image by either exposure blending or tone mapping different exposured images. You can download their trial here. If you buy Photomatix, you can use the discount coupon code "sandmania", which gives you 15% off the normal price.
Adobe Photoshop CS2 - This is used to final tune the image and to make any final adjustments. You can download a trial here.
Step 3 - Merge Images
First thing we will need to do is to load up our HDR images. With Photomatix opened, click HDR from the top menu and select Generate
This will bring up this screen. Click on browse to navigate and select the 3 or more bracketed images.
Then press ok.
Step 4 - Merge Images
This next window lets you specify options for creating the HDR image. The three photos of the church were taken by placing the camera on the floor, but we still check the align source images option to correct for small alignment problems that may have happened.
I keep the other settings the same as they are recommended, so let the program take the standard tone curve. You also have an option here to let the program attempt to reduce ghosting artifacts such as moving objects or ripples. For interior images I don't normally bother with this, unless there are people moving about in them.
Press OK
Step 5 - Photomatix Merged
Photomatix will now merge the different exposed images into a single HDR image that represents the complete tonal range captured by the photos.
This is way off what the final image will look like, so first off select HDR from the menu and select Tonemapping.
Step 6 - Photmatix Settings
Now this is where it starts to get interesting. This is the Photomatix settings screen that will allow you to tonemap the image. Now there is no general science to these sliders or some kind of magic setting. I have found each image requires something different and this really depends on your personal taste and the effect you want to achieve.
The trick is to adjust the settings to get a nice balanced image. You could be creative or go for something a little more fun. As mentioned before, for this particularly image I wanted something different and yet not too over the top.
Step 7 - Photmatix Settings
When experimenting with the sliders, there are some general rules which I normally follow;
Strength This controls the strength of local contrast enhancements. I am normally very flexible with this slider and just play around with it until I like what I see
Colour Saturation Controls the saturation of the RGB colour channels. The greater the saturation, the more intense the colour. I opted for a lower value in this instance to create a more darker atmosphere. You can also create a monochrome image here by taking away saturation and increasing the strength.
Light Smoothing Controls smoothing of light variations throughout the image. I never set this value below 0 as the image starts to get really wacky and cartoony.
Luminosity Adjusts the brightness of the shadows. Moving the slider to the right has the effect of boosting shadow details and brightening the image. Moving it to the left gives a more natural look to the tone mapped image. Again this slider is flexible, but don't take it over to the right as sometimes halos can start to appear.
Micro-smoothing I have this setting 70% of the time on 0. This setting really brings out the hidden details on the walls and floor that you didn't know where there.
Once finished just click on OK and wait for the image to process.
Step 8 - Photmatix Final
Once it has processed, click on File and then Save.
Step 9 - Photoshop Processing
Here you can make some final adjustments to the image in Photoshop or other image editing software. My workflow changes based on what I think the image needs but generally I check for these elements:
- Crop the image if necessary
- Adjust level and curves
- Sharpen the image using smart sharpen
- Shadow and highlight changes
With this particular image, I adjusted the curves slightly and sharpened it a little. Also I duplicated the layer and changed the blend mode to overlay. The opacity and fill values were brought right down to 30s region.
I find that with most interior shots, there is not a great need to go overboard with processing in Photoshop, but again this will be down to your own personal preferences. We now have the final image. All that needs to be done now is to merge the layers and save the image.
Step 10 - Photoshop Processing Extra
You could always take the image that one step further in Photoshop and try a various number of things.
Here I decided to turn the image into B/W, so added a saturation adjustment layer, bring the value right down to 0. This is just one example of what you can do.
If you find you have a lot of noise in the image, try using some kind of noise reduction software like Noise Ninja or Noiseware.
Noiseware - You can get 10% off Noiseware by using the coupon code 'sandmania'. You can check it out over on their Imagenomic Website
The coupon code applies to their full product line, including individual products, bundles and the Suite. Watch out for a Noiseware tutorial coming soon.
