Research Abstracts - 2007

Abstract

We introduce a new approach to tone management for photographs. Whereas traditional tone-mapping operators target a neutral and faithful rendition of the input image, we explore pictorial looks by controlling visual qualities such as the tonal balance and the amount of detail. Our method is based on a two-scale non-linear decomposition of an image. We modify the different layers based on their histograms and introduce a technique that controls the spatial variation of detail. We introduce a Poisson correction that prevents potential gradient reversal and preserves detail. In addition to directly controlling the parameters, the user can transfer the look of a model photograph to the picture being edited.

Goals

The goal of our work is to allow users to achieve a particular photographic look. To specify "look", we propose to use model photographs.

We focus on the tonal aspects of photos decoupled from their content. We have observed that photographs differ in their global contrast and in the variation of their local contrast. This inspires us to transfer tonal aspect of photographic look using a two-scale approach.

Our Technique

We use a two-scale decomposition to control largescale effects and the texture distribution separately. We quantify the look of an image using histograms over this decomposition, which affords both interactive control using a curve interface, and the ability to automatically transfer visual properties between images. In the latter, histograms of the components of a model image are forced upon a new input. Because we explore strong stylistic variations, we tend to perform larger modifications to the input than tone mapping. In particular, some looks require an increase in local contrast, which can produce halos if traditional techniques are used. We introduce a gradient constraint that prevents undesirable modifications. Finally, we post-process the image to achieve various effects such as soft focus, paper grain, and toning. The following figure summarizes our technique.

Results

More results are available on our website.

Conclusions

We have presented an approach to manipulate the tonal look of digital photographs. Using a combination of non-linear edgepreserving decomposition and linear analysis, we control both the large-scale tonal palette and the detail over an image. In particular, we manipulate the spatial variation of high-frequencies using a new textureness map that performs an edge-preserving analysis and manipulation of the high-frequency content. We have introduced a gradient constraint that preserves image content and prevents gradient reversal and halos.

Our method can be used to transfer the look of a model photograph or can be directly controlled using a simple interface. It allows for the exploration of a variety of styles. This work opens several areas of future research. It should be combined with approaches to control the color components of pictorial style. While early experiments with videos have shown that our technique itself is stable, we have found that the biggest challenge is the fluctuation created by auto-exposure, autofocus and the variation of motion blur when the camera moves.

This work has been published in Siggraph 2006 [1].

Acknowledgement

We thank the reviewers of the MIT Computer Graphics Group and the SIGGRAPH reviewers for insightful feedback. We are especially grateful to Eugene Hsu and Eric Chan for their expert comments on our prints. This work was supported by a National Science Foundation CAREER award 0447561 ¡°Transient Signal Processing for Realistic Imagery,¡± an NSF Grant No. 0429739 ¡°Parametric Analysis and Transfer of Pictorial Style,¡± and a grant from Royal Dutch/Shell Group. Fredo Durand acknowledges a Microsoft Research New Faculty Fellowship. Sylvain Paris was partially supported by a Lavoisier Fellowship from the French ¡°Ministere des Affaires Etrangeres.¡± Soonmin Bae is financially supported by the Samsung Lee Kun Hee Scholarship Foundation.

References:

[1] Soonmin Bae, Sylvain Paris, and Frédo Durand. Two-scale tone management for photographic look. In Proceedings of SIGGRAPH 2006.

[2] Frédo Durand and Julie Dorsey. Fast Bilateral Filtering for the Display of High-Dynamic-Range Images . In Proceedings of SIGGRAPH 2002.

[3] Elmar Eisemann and Frédo Durand. Flash photography enhancement via intrinsic relighting. In Proceedings of SIGGRAPH 2004.

[4] Sylvain Paris and Frédo Durand. A fast approximation of the bilateral filter using a signal processing approach. In Proceedings of European Conference on Computer Vision 2006.