Recovering spectral data from natural scenes with an RGB digital camera and colored filters

Valero, Eva M.; Nieves, Juan Luis; Nascimento, Sérgio M. C.; Amano, Kinjiro; Foster, David H.

doi:10.1002/col.20339

Cited by 62 publications

(56 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Extending the use of the multispectral imaging system from heavily constrained environments to real-world applications is still an open challenge. One of the major obstacles is calibration of the multispectral camera according to the scene illuminant [7][8][9][10][11]. In this work, we investigate the use of illuminant estimation algorithms for multispectral imaging systems.…”

Section: Introductionmentioning

confidence: 99%

Illuminant estimation in multispectral imaging

Khan¹,

Thomas²,

Hardeberg³

et al. 2017

J. Opt. Soc. Am. A

View full text Add to dashboard Cite

With the advancement in sensor technology, the use of multispectral imaging is gaining wide popularity for computer vision applications. Multispectral imaging is used to achieve better discrimination between the radiance spectra, as compared to the color images. However, it is still sensitive to illumination changes. This study evaluates the potential evolution of illuminant estimation models from color to multispectral imaging. We first present a state of the art on computational color constancy and then extend a set of algorithms to use them in multispectral imaging. We investigate the influence of camera spectral sensitivities and the number of channels. Experiments are performed on simulations over hyperspectral data. The outcomes indicate that extension of computational color constancy algorithms from color to spectral gives promising results and may have the potential to lead towards efficient and stable representation across illuminants. However, this is highly dependent on spectral sensitivities and noise. We believe that the development of illuminant invariant multispectral imaging systems will be a key enabler for further use of this technology.

show abstract

Section: Introductionmentioning

confidence: 99%

Illuminant estimation in multispectral imaging

Khan¹,

Thomas²,

Hardeberg³

et al. 2017

J. Opt. Soc. Am. A

View full text Add to dashboard Cite

show abstract

“…This can be achieved with simple color filters as shown by Valero et al (2007), who used sequential observations through different acrylic filters (e.g., magneta, orange, green, and blue) to improve the spectral resolution of an RGB camera system. Effective observations of rapidly varying processes, such as the aurora, would require simultaneous measurements using several cameras in order to achieve the same results.…”

Section: Discussionmentioning

confidence: 99%

Auroral spectral estimation with wide-band color mosaic CCDs

Jackel

Unick

Syrjäsuo

et al. 2014

Geosci. Instrum. Method. Data Syst.

View full text Add to dashboard Cite

Abstract. Optical aurora can be structured over a wide range of spatial and temporal scales with spectral features that depend on the energy of precipitating particles. Scientific studies typically combine data from multiple instruments that are individually optimized for spatial, spectral, or temporal resolution. One recent addition combines all-sky optics with color mosaic CCD (charge-coupled device) detectors that use a matrix of different wide-band micro-filters to produce an image with several (often three) color channels. These devices provide sequences of two dimensional multispectral luminosity with simultaneous exposure of all color channels allowing interchannel comparison even during periods with rapidly varying aurora. At present color auroral image data are primarily used for qualitative analysis. In this study a quantitative approach based on Backus-Gilbert linear inversion was used to better understand the effective spectral resolution of existing and proposed instruments.Two spectrally calibrated commercial detectors (Sony ICX285AQ and ICX429AKL) with very different color mosaics (RGB (red, green, blue) vs. CYGM (cyan, yellow, green, magenta)) were found to have very similar spectral resolution: three channels with FWHM (full-width halfmaximum) ≈ 100 nm; a NIR (near infrared) blocking filter is important for stabilizing inversion of both three-channel configurations. Operating the ICX429AKL in a noninterlaced mode would improve spectral resolution and provide an additional near infrared channel. Transformations from arbitrary device channels to RGB are easily obtained through inversion. Simultaneous imaging of multiple auroral emissions may be achieved using a single-color camera with a triplepass filter. Combinations of multiple cameras with simple filters should provide ∼ 50 nm resolution across most of the visible spectrum. Performance of other instrument designs could be explored and compared using the same quantitative framework.

show abstract

“…However for many applications, the illuminant may not be known beforehand, for example in the case of natural outdoor scenes. One way of retrieving information about the illuminant is to capture images by placing a standard color target, such as the Macbeth Color Checker in the scene, as done in the multispectral image database by Yasuma et al [11], or a Munsell gray chart as used by Valero et al [12] to recover spectral data from natural scenes. But the imaging process then becomes constrained, and may not be practicable in many situations.…”

Section: Introductionmentioning

confidence: 99%

Spectrogenic imaging: A novel approach to multispectral imaging in an uncontrolled environment

Shrestha¹,

Hardeberg²

2014

Opt. Express

View full text Add to dashboard Cite

Abstract:Increasing the number of imaging channels beyond the conventional three has been shown to be beneficial for a wide range of applications. However, it is mostly limited to imaging in a controlled environment, where the capture environment (illuminant) is known a priori. We propose here a novel system and methodology for multispectral imaging in an uncontrolled environment. Two images of a scene, a normal RGB and a filtered RGB are captured. The illuminant under which an image is captured is estimated using a chromagenic based algorithm, and the multispectral system is calibrated automatically using the estimated illuminant. A 6-band multispectral image of a scene is obtained from the two RGB images. The spectral reflectances of the scene are then estimated using an appropriate spectral estimation method. The proposed concept and methodology is generic one, as it is valid in whatever way we acquire the two images of a scene. A system that can acquire two images of a scene can be realized, for instance in two shots using a digital camera and a filter, or in a single shot using a stereo camera, or a custom color filter array design. Simulation experiments using a stereo camera based system confirms the effectiveness of the proposed method. This could be useful in many imaging applications and computer vision.

show abstract

Recovering spectral data from natural scenes with an RGB digital camera and colored filters

Cited by 62 publications

References 31 publications

Illuminant estimation in multispectral imaging

Illuminant estimation in multispectral imaging

Auroral spectral estimation with wide-band color mosaic CCDs

Spectrogenic imaging: A novel approach to multispectral imaging in an uncontrolled environment

Contact Info

Product

Resources

About