Posted on August 27, 2006
Tags: barcamp, bmann, cathycracks, vancouver

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PhotoCamp notes

Here are my notes from my PhotoCamp presentation I gave at BarCamp Vancouver over the weekend.

Idea

While we have used digital cameras much the same way that we have film cameras, digital photography has fundamental differences from conventional film-based devices. The ability to interact with sensors has opened up a number of opportunities for the capture of novel image types. The combination of different methods of capture with new processing techniques allows for new image forms. The umbrella term for this family of techniques is known in the research community as computational photography.

There is ongoing research in changing all the major clusters of the photographic process. People have investigated changes in lighting, camera optics, digital sensors, and image procesing. The point of the talk was to provide an overview of what interesting features might be available on your camera in the future.

Fourier slice photography

This paper presents a camera that samples the 4D light field on its sensor in a single photographic exposure. This is achieved by inserting a microlens array between the sensor and main lens, creating a plenoptic camera. Each microlens measures not just the total amount of light deposited at that location, but how much light arrives along each ray. By re-sorting the measured rays of light to where they would have terminated in slightly different, synthetic cameras, we can compute sharp photographs focused at different depths. This property allows us to extend the depth of field of the camera without reducing the aperture, enabling shorter exposures and lower image noise. Especially in the macrophotography regime, we demonstrate that we can also compute synthetic photographs from a range of different viewpoints.

• Plenoptic camera
• Refocus image gallery

Flash-no flash photography

This technique enhances the appearance of photographs shot in dark environments by combining a picture taken with the available light and one taken with the flash. It preserves the ambiance of the original lighting and insert the sharpness and more reliable color information from the flash image. It uses the bilateral filter to decompose the two images into detail and large-scale layers. It reconstructs the image using the large scale of the available lighting and the detail of the flash. We detect and correct artifacts due to the flash shadow. The output images provide the combined advantages of available illumination and flash photography.

• Flash Photography Enhancement via Intrinsic Relighting

Graph processing

This framework uses graph-cut optimization to choose good seams within the constituent images so that they can be combined as seamlessly as possible; and gradient-domain fusion to further reduce any remaining visible artifacts in the composite. The power of this framework lies in its generality; we show how it can be used for a wide variety of applications, including "selective composites" (for instance, group photos in which everyone looks their best), relighting, extended depth of field, panoramic stitching, clean-plate production, stroboscopic visualization of movement, and time-lapse mosaics.

• Interactive digital photomontage

Structured photography

Photo tourism is a system for browsing large collections of photographs in 3D. Our approach takes as input large collections of images from either personal photo collections or Internet photo sharing sites, and automatically computes each photo's viewpoint and a sparse 3D model of the scene. Our photo explorer interface enables the viewer to interactively move about the 3D space by seamlessly transitioning between photographs, based on user control.

• Photo tourism paper
• Microsoft Photosynth
• Youtube video

High dynamic range imaging

One of the most interesting advances in photography and imaging is what is known as high dynamic range imaging (HDR or HDRI). In the context of photography, the purpose is to extend the dynamic range (or ratio of brightest to darkest areas) beyond it's current limitations. The goal is to capture all of the luminance data for later, and not have images that have areas that are overexposed or underexposed. For more information on HDRI and how it applies to photography, check out this article.

The process of HDR imaging follows the same basic flow as conventional photography. You capture the scene via some method, store and process it, then display it by some means, but all of the methods for HDR images differ from their conventional counterparts. On the acquisition end, there are several means of creating HDR images. For static scenes, an exposure sequence can be combined into a single HDR image, while new HDR cameras are also under development. On the display end, there are two categories, tonemapping and native display. Tonemapping is method of compressing the image contrast to the dynamic range of a conventional display. There is much more to tonemapping than the Flickr group and some operators work better than others, and you need to know what you want to do in order to pick the right one. The other option is to use a high dynamic range display, such as the ones by BrightSide Technologies (warning: shameless plug).

• My del.icio.us tags
• Photography software: Photosphere, FDR tools, HDR Shop, Photomatix, Photogenics
• High Dynamic Range Imaging book