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03.28.2011

High Dynamic Range Imaging with the Sigma DP1x

Tips & Tricks for top quality HDR shots from Sigma’s serious compact cameras

Jack Howard

There are number of key things in the feature set of Sigma’s Foveon-chipped compact cameras, the DP1s, DP1x, DP2 and DP2s  that add up to a class of cameras that is, in so many ways, perfect for serious High Dynamic Range Imaging in a very small package.

A three-shot auto bracket burst at +/-3 EVs around the metered exposure at ISO 100 f/7.1 with the Sigma DP1x gives this tone mapped high dynamic range image great detail and color information through an amazingly wide dynamic range. I used the popular HDR program Photomatix Pro to merge and tone map this file, and applied a little perspective adjustment in Adobe Photoshop CS5 Extended to fix keystoning. This is College Hall on Douglass Campus of Rutgers University in New Brunswick, and is probably my favorite building at RU.

At its simplest, High Dynamic Range Imaging is a multiple-photo field technique combined with specialized processing of these multiple shots to allow a much greater dynamic range than is possible with traditional single-shot photography. This allows for much more visual information in shadows and highlights for very challenging, high contrast scenes–think of an indoor/outdoor architectural shoot, or a dimly lit cathedral with illuminated stained glass, or even simply bright midday conditions, for example–without having to deal with blocked shadows or clipped and blown highlights.

But in practice, it can get a lot more complicated because those bracketed photos need to be merged together into a single image and any slight differences between frames–clouds, tree branches, moving people, cars, and flags flapping in the wind–for example, can cause problems.

This sign, quoting the song lyrics, stands on the shore of the Passion Puddle on Douglass Campus, Rutgers University. The 28mm (equiv) f/4 lens of the Sigma DP1x allowed me to get right on top of this sign, and nicely frame the pond at f/7.1, ISO 100 for a three-shot burst at +/-3 EVs to give clean shadows, crisp highlights, and rich color information throughout the scene, shot near mid day. I ran this shot through Unified Color’s HDR Express program, which is amazingly powerful, and also amazingly easy for beginners to get great, realistic results.

I think there are a handful of critical features in a compact camera that will make it much stronger as a tool for the serious HDRI photographer. The Sigma DP1x (and every DP camera, for that matter) packs these serious big-camera quality features for profession-quality HDRI into their small–but big-chipped–bodies:

  • Full manual exposure control.
  • A Built-in Auto Exposure Bracket sequence that can span up to 3 full EVs between exposures for a minimum of three shots.
  • RAW format AEB sequence capture speed. The faster the source images can be captured, the better. THE DP cameras grab those RAW shots at 3 frames per second.
  • One-touch-and-done AEB burst capture.
  • Manual focus mode to eliminate lens refocusing at any point during HDRI sequence capture. (This is particularly important for some exceedingly high-contrast scenes that require even more bracketing that a +/-3 EV for 3 shots AEB sequence can handle. You can either adjust the shutter speed manually to span a wider EV range, or you can do two AEB bursts combined with exposure compensation to expand the dynamic range even wider than the respectably wide base AEB sequence.)
  • Exceptional image quality at lowest ISO. HDRI is primarily a tripod-based endeavor, so I am most interested in maximizing image quality by sticking with low, slow ISOs. The results I can achieve at ISO 100 with a camera like the DP1x are just amazing!

 

The sharp 28mm (equiv) f4.0 wide angle lens, combined with the DPIx’s big Foveon chip, and a +/-3 AEB sequence merged and worked up in HDR Express gives great detail and tonal range information from the darkest sections of the rusting sculpture to the most delicate wispy clouds in this colorful midday rendition of the sculpture garden next to the Mason Gross buildings on Douglass Campus.

Now, many photographers get wary when they hear the term “HDRI” and think that the results always and universally look ersatz, artificial, or over-processed.

However, part of the reason for this is because too often photographers don’t fully capture the dynamic range of the scene, due to their use of cameras with AEB sequences that aren’t as wide as +/-3 EVs for a three shot burst. And then, to make up for this, and to achieve an “HDR feel”, aggressive settings are applied via software, which can create that typically overprocessed, hypercolored, haloed edge style of imagery that is, all too often, mistaken as the only thing HDRI photography can produce.

If you don’t already know, I hope you are discovering through this piece, that the results of HDRI photography can be very dramatic and colorful, without necessarily being saccharine. Of course, having the right camera for the job, such as the Sigma DP1x, is a big part of making these photos.

Yes, this was made with the pocketable Sigma DP1x! The wide lens, combined with the big Foveon sensor and a +/-3 AEB burst while bracing the camera against the steel support cable makes for great shallow Depth of field when close-focused, even at f/7.1! The source images were merged and processed in Photomatix Pro. This is the class of 1926 Bridge over the ravine on Douglass Campus, Rutgers University, a footbridge that bounces nicely during high-traffic times!

  
 
 
 

Here is a 100% pixel view of the sharp-focused area of the above photo. Notice how clean the pixel values are from darkest to lightest areas of this frame, which is a great advantage to HDRI workflows for stationary subjects. Done properly, HDRI can be a naturally noise-diminishing workflow for every image from every camera. Of course, the better quality the source images, the better quality the results, and the DP1x lets you start with excellent quality source images.

   Jack’s Tips for HDRI photography with the Sigma DP1x (and the rest of the DP cameras)
  • Use a tripod, whenever possible, to ensure alignment of frames. You an also steady the flat-bottomed DP1x on a stable surface, and go vertically on the edge of a table or ledge with most of the left  side of the camera, if it isn’t possible to use a tripod.
  • Shoot Sigma’s X3F RAW format, then process these shots at double size through Sigma Photo Pro 4.2 for large, high quality source images to run into HDR Software.
  • Set the camera to either manual exposure or aperture priority mode to pick your centered exposure, and use Auto Bracketing at up to +/- 3 EVs to capture the full dynamic range of the scene. Your darkest frame histogram and your brightest frame histogram should show significant clipping of values.
  • When using AEB, you should always have the camera set to burst capture mode. The DP1x will fire off your three frames, then stop.
  • If you are changing exposures completely manually, you should be in single-shot mode to make sure you only snap one frame each touch. And if you are doing this, you should definitely be in manual focusing mode.
  • Scenes with no moving elements are the easiest for beginners to master. (Moving objects in a frame can present challenges, but can be tackled with some software tricks.)
  • Look for color contrast and textural contrast in your compositions, as the increased tonal range of tone mapped images can play some tricks with tonal range contrast perception.
  • Be patient! It takes a little while for the DP1x to process that 3-shot X3F RAW burst, but it will be worth it!

  

Here’s one of those classic exposure range conundrums that can be tackled with HDRI photography. Three exposures were made to captured the deepest shadow details inside the covered bridge (which is right next to the suspension bridge above) and the bright bricks of the building lit by direct midday sun. I placed the flat bottom of the Sigma DP1x right on the boards of the bridge to fire off the series of perspective shots that were made into a single image with the powerful, yet simple-to-use HDR Express.

 

How I prep X3F Raw files for HDR Merging

Usually, I recommend using straight-from-camera RAW files to merge into a single HDR image, but when I’m working with Sigma X3F RAW files, I change my workflow a little bit to take advantage of the Foveon chip’s Bayer-less design to smoothly upsample the source images in Sigma Photo Pro 4.2 for big, top-quality source TIFFs to bring into my HDR programs. First, obviously, I pull all the photos from my camera card into a single folder, and then I open that folder using the folder navigation window in Sigma Photo Pro 4.2. I make sure all photos are highlighted and click the “Save Images As..” button, which launches the big dialogue box. I click the “New Folder” button and name a nested subfolder “Double Size” as the destination. I want these images processed straight from the camera’s capture decisions, so I tick “X3F” in the Adjustment Mode field and select “Double Size” as the Output Image Size, keep the color as sRGB, and select 16-bit TIFF as the file type, which creates big, beautiful 5280 x 3520 pixel source photos that will bring a wealth of information into our merged HDR image. I click “Save” and let my computer chug away as Sigma Photo Pro churns out all the big 16-bit files.

Once all the Double Sized TIFFs are created, I launch Adobe Bridge CS5, which is a great thumbnail viewer, regardless of what HDR program I’m going to use. I pick a source image sequence, and either drag and drop my three images onto a dock icon for any of the several freestanding HDRI programs I regularly use (including Photomatix, HDR Expose, HDR Express, or FDRTools) or go to Tools>Photoshop>Merge to HDR Pro to work up the HDR image in Adobe Photoshop CS5. If you are on a PC, your screen may look a bit different, but you can still take the photos from Bridge into any of these programs.

 

For the photos you see in this article on HDR photography with the Sigma DP1x, I worked with Adobe Photoshop CS5 Extended (top left), Photomatix Pro (top right), HDR Expose (lower left) and HDR Express (lower left.) Each of these programs is capable of making great HDRI images.

Video Tutorials for the HDR programs I used in this article

Adobe Photoshop CS5 is an amazing tool with very unique 32-bit layer and local selection capabilities. You can learn a lot more about how I work with HDR photography with Photoshop CS5 in this screencast tutorial I presented last summer.

Photomatix Pro from HDRSoft is a wildly popular HDR program, that is capable of very dramatic results. You can learn much more about working in Photomatix Pro  in this video tutorial from their website.

Unified Color makes two impressive standalone HDR programs. HDR Expose is a very rich 32-bit editing environment that has a very powerful toolkit for the advanced digital photographer. You can learn more about HDR Expose in this video tutorial.

HDR Express, also from Unified Color, is very easy to learn for beginners, but behind this simple-to-grasp user interface is an amazingly powerful processing engine. This informative video shows how to use HDR Express in conjunction with Adobe Lightroom . If you want to skip the Lightroom part, jump to the 5:30 mark in this video.

Have any question on HDRI and the DP cameras? Let me know! And of course, we love it when fans share photos on Sigma’s Facebook page!

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  1. That’s Great!!!

  2. Hello Jack

    I wonder what you think about use of HDR in Sigma compacts – after all the Foveon sensor has a very good dynamic range. Isn’t the Sigma Photo Pro sufficient?

  3. Hi Kris, yes, the Foveon Sensors have great D-range performance in single image capture, especially in X3F Raw capture mode. Additionally, these are amazingly professional-quality tools for compact HDRI photography when a wider dynamic range is wanted or needed.