I recently posted a few images of mine over in the Land and Seascapes forum, here, and a few of the guys were interested in the process involved in HDR imaging, so I've gone ahead and put together my own little guide to HDR, showing the procedure and the processing techniques i use. I hope everyone can get something out of it.
High Dynamic Range photography is all about increasing the dynamic range of the resulting image. It's not about making an image look as unrealistic as possible, but it does open up the avenue of being a little more artistic with the processing. I see a lot of poorly processed HDR images around the place, which has led to HDR processing having a bit of a bad reputation with a lot of photographers. There is no right and wrong in HDR, but there is good and bad, as is the case with photography in general. However, I realise the whole good & bad thing is completely subjective anyway... so I won't even attempt to define what makes good and bad HDR photography. I'm sure there are a lot of people that don't find my HDR work terribly pleasing... and that's fine. I'm the artist, and i create the artwork that i want to, first and foremost, for myself.
In this guide I will detail the procedure I personally use to make my HDR images. In no way do I believe this is the right or the only way to do it, it's just the method I have developed through experience and reading a bunch of HDR tutorials myself. Hopefully, anyone who reads this will at least take a few tips or tricks away from it.
What you need
Camera - that is capable of taking 3-5 bracketed images. Many cameras can do this these days. I started making HDR images with a IXUS70 (released ~2006) with the CHDK firmware upgrade that enabled bracketing and . These days, most DSLRs have the ability to shoot bracketed images, except maybe the base model of each brand. For example, I don't think the D3000 & D3100 have the ability. Anyway, check your manual if you are unsure how to put your camera into bracketing mode.
? - Not totally necessary for all occasions, but depending on the situation and the lighting, you may need one. Really depends how keen you are to bump the up on your camera, to keep the down. For the brightest of the bracketed images, the will obviously be the longest. If this image cannot be taken at a fast enough to obtain a image, then either bump up the , or use a .
Software – I use Lightroom 3, Photoshop CS5 and Photomatix Pro 4 during the process. What each is used for will be discussed further on.
Taking the images
As a general rule, I take the 3 images at -2,E,+2. This generally gets all the highlights in the -2 image without having any highlights being blown out, and gets all the darks in the +2 image without having any clipped blacks. Of course, in the field you should check your histogram to see if you're getting all the required detail. The middle image provides a lot of the mid range details, and generally gets a good of the subject, if there is one.
OK, as with every other photo I take, it gets imported into lightroom. I generally edit the metered first.
This first pass through Lightroom is simply going to adjust the angle of the image (if it's not flat), correct the white balance if needed, correct any distortions and do a first pass noise reduction. Correcting chromatic aberrations at this stage is important, as leaving them will result in them being heavily amplified in the final product. Same goes for noise; the HDR process generally results in the original noise being amplified somewhat. Therefore, reducing the noise at this stage will reduce the noise in the final image, however, as always, it's important to reduce the noise without losing any important details. Take the time to find the balance. Once I'm happy with the metered image, I right click on the image and copy the develop settings from it and paste them into the -2 & +2 images. I then select all 3 images, right click and select edit in > open as layers in photoshop.
Select all 3 layers and go to Edit menu, and select auto-align layers. Leave the align processing on auto. Once the images are aligned, go to File > Scripts > Export layers to files. Keep the images as 16 bit tifs.
Load the 3 bracketed images into Photomatix. I generally don't use the extra features of photomatix to correct aberrations and ghosting, as I’ve heard it does a reasonably foul job, but its up to you if you want to try it. Once the HDR image is combined, you get a screen with a lot of sliders on it.
Set the processing to 'detail enhancer'. Basically its the first set of sliders that are the most important. I usually set the strength to somewhere between 80-90, the saturation to taste, and the smoothing should be up at maximum or somewhere close to maximum. As for the rest of the settings, you're welcome to play, but I generally don't touch them. Sometimes I will adjust the white and black clipping points just to even out the histogram, but not much else is done here. After processing the image, save and exit.
Open the image in Photoshop and go for it. The rest is really up to you and what you need to do is determined by the individual image. Sometimes you do have to be a little heavy handed with the contrast and curves adjustments to cut through the haziness of the original HDR image. I use a lot of layer masking to edit individual parts of an image – Topaz Remask is fantastic for this, and I stole my fiancee's graphics tablet (which I bought for her) which speeds the masking process up a lot.
Various other adjustments I use frequently include levels, colour balance, selective colour, hue/saturation, brightness/contrast, shadows/highlights, etc.
Two things that can often be a problem in HDR imaging is colour over-saturation and haloing. I often have a number of desaturation layers in my projects to bring the image back into the realms of realism. Haloing is a tougher fix, often if you are careful in photomatix you can avoid any halos, but sometimes it is inevitable. Fixing this in photoshop is a tutorial in itself, which I will attempt at a later date.
Once I'm happy with the image, I save and import the new image into lightroom.
Any final adjustments are made here. Mild white balance, clarity and sometimes adjustment. Normally not a great deal as I'm usually fairly happy by the time I'm finished in Photoshop.
And that's about it. I hope by reading this far, you learned something. And please, if you have any pointers for me, I'm always looking to learn, so let me know!