Breneman - Revision history

imported>Projects221: /* Appendix I - Code and Data */

2013-03-21T04:00:27Z

Appendix I - Code and Data

← Older revision		Revision as of 04:00, 21 March 2013
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	= Appendix I - Code and Data =		= Appendix I - Code and Data =
	In the ~~hopes~~ that the techniques used may be illustrated best by example, the MATLAB code used to perform the multispectral analysis and calibration is available below along with sample data from the project.		In the belief that the techniques used may be illustrated best by example, the MATLAB code used to perform the multispectral analysis and calibration is available below along with sample data from the project.
	==Code==		==Code==
	All code was written in MATLAB R2012a for Mac OSX, Mountain Lion. External dependencies include the MATLAB Image Processing Toolkit, MATLAB Optimization Toolkit, and the ISET toolkit.		All code was written in MATLAB R2012a for Mac OSX, Mountain Lion. External dependencies include the MATLAB Image Processing Toolkit, MATLAB Optimization Toolkit, and the ISET toolkit.

imported>Projects221: /* Appendix I - Code and Data */

2013-03-21T03:55:25Z

Appendix I - Code and Data

← Older revision		Revision as of 03:55, 21 March 2013
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	= Appendix I - Code and Data =		= Appendix I - Code and Data =
			In the hopes that the techniques used may be illustrated best by example, the MATLAB code used to perform the multispectral analysis and calibration is available below along with sample data from the project.
	==Code==		==Code==
	~~[[File:CodeFile~~.~~zip]]~~		All code was written in MATLAB R2012a for Mac OSX, Mountain Lion. External dependencies include the MATLAB Image Processing Toolkit, MATLAB Optimization Toolkit, and the ISET toolkit.

			[[File:UnderwaterColorCode.zip]]
	==Data==		==Data==
	A total of 2.5GB of image data were collected for this project, and are available upon request. The extracted RGB color patch data, colorimeter responses, and SX260HS responsivity data are available below.		A total of 2.5GB of image data were collected for this project, and are available upon request. The extracted RGB color patch data, colorimeter responses, and SX260HS responsivity data are available below.
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	[[File:CanonSX260HSResponsivity.zip]]		[[File:CanonSX260HSResponsivity.zip]]

	==Presentation==		==Presentation==
	This project was given as a 5-minute presentation to the PSYCH221 Winter 2013 class at Stanford. The presentation files used are linked below.		This project was given as a 5-minute presentation to the PSYCH221 Winter 2013 class at Stanford. The presentation files used are linked below.

imported>Projects221: /* Data */

2013-03-21T03:51:46Z

Data

← Older revision		Revision as of 03:51, 21 March 2013
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	==Data==		==Data==
	[[File:~~DataFile~~.zip \| zip ~~file with my data~~]]		A total of 2.5GB of image data were collected for this project, and are available upon request. The extracted RGB color patch data, colorimeter responses, and SX260HS responsivity data are available below.

			[[File:UnderwaterColorData.zip]]

			[[File:CanonSX260HSResponsivity.zip]]

	==Presentation==		==Presentation==

imported>Projects221: /* Calibrating the Underwater Color Rig */

2013-03-21T03:44:19Z

Calibrating the Underwater Color Rig

← Older revision		Revision as of 03:44, 21 March 2013
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	Canon does not publish the responsivities of the SX260HS point-and-shoot. Furthermore, the SX260HS does not provide a means to access the RAW image pixel values so the values must be inferred from the camera's 12Megapixel high-resolution JPEG images. These JPEG images have passed through the camera's image processing pipeline. Although the high pixel density limits artifacts in the JPEG compressor, the image processing pipeline's color balancing algorithm is also unknown. To guarantee data consistency the camera's color balance was fixed at the beginning of the project's datacollection phase and measured later in the SCIEN lab.		Canon does not publish the responsivities of the SX260HS point-and-shoot. Furthermore, the SX260HS does not provide a means to access the RAW image pixel values so the values must be inferred from the camera's 12Megapixel high-resolution JPEG images. These JPEG images have passed through the camera's image processing pipeline. Although the high pixel density limits artifacts in the JPEG compressor, the image processing pipeline's color balancing algorithm is also unknown. To guarantee data consistency the camera's color balance was fixed at the beginning of the project's datacollection phase and measured later in the SCIEN lab.

	To measure the SX260HS responsivities, the camera was exposed to a series of illuminants created by a Newport Oriel Cornerstone 130 monochromatic light. The illuminants were directed at a white color target and the resulting spectrum was captured photographically by the SX260HS and measured by a Photo Research [http://www.photoresearch.com/current/pr650.asp PR-650 Spectra-Scan] colorimeter. A graphic of the responsivity measurement setup is shown below. To guarantee the SX260HS captured images at the correct time, its shutter was computer controlled via CHDK firmware and an Arduino trigger signal.		To measure the SX260HS responsivities, the camera was exposed to a series of illuminants created by a Newport [http://www.newport.com/Cornerstone153-130-1-8-m-Monochromator/378357/1033/info.aspx Oriel Cornerstone 130] monochromatic light. The illuminants were directed at a white color target and the resulting spectrum was captured photographically by the SX260HS and measured by a Photo Research [http://www.photoresearch.com/current/pr650.asp PR-650 Spectra-Scan] colorimeter. A graphic of the responsivity measurement setup is shown below. To guarantee the SX260HS captured images at the correct time, its shutter was computer controlled via CHDK firmware and an Arduino trigger signal.

	[[File:MeasuringResponsivity.jpg\|center]]		[[File:MeasuringResponsivity.jpg\|center]]

imported>Projects221: /* Calibrating the Underwater Color Rig */

2013-03-21T03:43:37Z

Calibrating the Underwater Color Rig

← Older revision		Revision as of 03:43, 21 March 2013
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	Canon does not publish the responsivities of the SX260HS point-and-shoot. Furthermore, the SX260HS does not provide a means to access the RAW image pixel values so the values must be inferred from the camera's 12Megapixel high-resolution JPEG images. These JPEG images have passed through the camera's image processing pipeline. Although the high pixel density limits artifacts in the JPEG compressor, the image processing pipeline's color balancing algorithm is also unknown. To guarantee data consistency the camera's color balance was fixed at the beginning of the project's datacollection phase and measured later in the SCIEN lab.		Canon does not publish the responsivities of the SX260HS point-and-shoot. Furthermore, the SX260HS does not provide a means to access the RAW image pixel values so the values must be inferred from the camera's 12Megapixel high-resolution JPEG images. These JPEG images have passed through the camera's image processing pipeline. Although the high pixel density limits artifacts in the JPEG compressor, the image processing pipeline's color balancing algorithm is also unknown. To guarantee data consistency the camera's color balance was fixed at the beginning of the project's datacollection phase and measured later in the SCIEN lab.

	To measure the SX260HS responsivities, the camera was exposed to a series of illuminants created by a Newport Oriel Cornerstone 130 monochromatic light. The illuminants were directed at a white color target and the resulting spectrum was captured photographically by the SX260HS and measured by a Photo Research PR-650 Spectra-Scan colorimeter. A graphic of the responsivity measurement setup is shown below. To guarantee the SX260HS captured images at the correct time, its shutter was computer controlled via CHDK firmware and an Arduino trigger signal.		To measure the SX260HS responsivities, the camera was exposed to a series of illuminants created by a Newport Oriel Cornerstone 130 monochromatic light. The illuminants were directed at a white color target and the resulting spectrum was captured photographically by the SX260HS and measured by a Photo Research [http://www.photoresearch.com/current/pr650.asp PR-650 Spectra-Scan] colorimeter. A graphic of the responsivity measurement setup is shown below. To guarantee the SX260HS captured images at the correct time, its shutter was computer controlled via CHDK firmware and an Arduino trigger signal.

	[[File:MeasuringResponsivity.jpg\|center]]		[[File:MeasuringResponsivity.jpg\|center]]

imported>Projects221: /* References - Resources and related work */

2013-03-21T03:42:45Z

References - Resources and related work

← Older revision		Revision as of 03:42, 21 March 2013
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	[3] Brian A. Wandell, Foundations of Vision, Chapter 9. https://www.stanford.edu/group/vista/cgi-bin/FOV/chapter-9-color/#Linear_Models		[3] Brian A. Wandell, Foundations of Vision, Chapter 9. https://www.stanford.edu/group/vista/cgi-bin/FOV/chapter-9-color/#Linear_Models

			[4] Jong-Il Park, Moon-Hyun Lee, Michael D. Grossberg, and Shree K. Nayar "Multispectral Imaging Using Multiplexed Illumination" Computer Vision, 2007. ICCV 2007. IEEE 11th International Conference on

	'''Software'''		'''Software'''

imported>Projects221: /* Underwater Spectra */

2013-03-21T03:39:40Z

Underwater Spectra

← Older revision		Revision as of 03:39, 21 March 2013
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	[[File:CombinedLinearSystem.png\|center\|500px]]		[[File:CombinedLinearSystem.png\|center\|500px]]

	The color patch reflectivities in the model have been merged via element-by-element multiplication to form a single combined spectral response for each color patch. There are a total of 7 usable color targets within each image and 3 pixel color values per target resulting in a total of 21 linear equations usable for estimating the illuminant. There are a total of 51 spectral bands in the responsivity matrix of the color filter array and consequently 51 unknown values in the illuminant estimate. This results in an underdetermined system. To solve the system, an additional smoothness constraint was applied by developing the following optimization objective function, inspired by the multispectral estimation techniques of Park et. al.		The color patch reflectivities in the model have been merged via element-by-element multiplication to form a single combined spectral response for each color patch. There are a total of 7 usable color targets within each image and 3 pixel color values per target resulting in a total of 21 linear equations usable for estimating the illuminant. There are a total of 51 spectral bands in the responsivity matrix of the color filter array and consequently 51 unknown values in the illuminant estimate. This results in an underdetermined system. To solve the system, an additional smoothness constraint was applied by developing the following optimization objective function, inspired by the multispectral estimation techniques of Park et. al [4].

	[[File:OptimizationObjective.png\|center\|200px]]		[[File:OptimizationObjective.png\|center\|200px]]

imported>Projects221: /* PVC Rig */

2013-03-21T03:38:49Z

PVC Rig

← Older revision		Revision as of 03:38, 21 March 2013
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	=== PVC Rig ===		=== PVC Rig ===
	A PVC frame was constructed to provide better control over image framing. A standardized color metric, the XRite color checker card, was attached. The PVC frame holds the color card a fixed distance of 12" from the camera and a surplus analog depth gauge is attached near the upper left side of the color target. The color card was enclosed between sheets of 3/8-inch thick clear acrylic from [http://www.tapplastics.com/ TAP Plastics]. Venting holes drilled in the PVC pipe allow air to escape from the frame making the rig negatively buoyant. The rig is lowered underwater by nylon line attached to an eye bolt in the center support.		A PVC frame was constructed to provide better control over image framing. A standardized color metric, the [http://xritephoto.com/ph_product_overview.aspx?ID=820 XRite] color checker card, was attached. The PVC frame holds the color card a fixed distance of 12" from the camera and a surplus analog depth gauge is attached near the upper left side of the color target. The color card was enclosed between sheets of 3/8-inch thick clear acrylic from [http://www.tapplastics.com/ TAP Plastics]. Venting holes drilled in the PVC pipe allow air to escape from the frame making the rig negatively buoyant. The rig is lowered underwater by nylon line attached to an eye bolt in the center support.

	[[File:UnderwaterColorRigV1.jpg\|frame\|center\|Original acrylic color card]]		[[File:UnderwaterColorRigV1.jpg\|frame\|center\|Original acrylic color card]]

imported>Projects221: /* References - Resources and related work */

2013-03-21T03:36:50Z

References - Resources and related work

← Older revision		Revision as of 03:36, 21 March 2013
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	Image Systems Engineering Toolbox http://imageval.com/		Image Systems Engineering Toolbox http://imageval.com/

			Canon Hack Development Kit http://chdk.wikia.com/wiki/CHDK

	= Appendix I - Code and Data =		= Appendix I - Code and Data =

imported>Projects221: /* Underwater Color Rig Data */

2013-03-21T03:36:06Z

Underwater Color Rig Data

← Older revision		Revision as of 03:36, 21 March 2013
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	==Underwater Color Rig Data==		==Underwater Color Rig Data==
	The color rig's Canon SX260HS camera was programmed using the CHDK firmware to snap photos of the onboard Xrite color checker at an interval of approximately 2 seconds, limited by the camera's onboard processor. A single descent from the surface to 90 feet and back produces between 100 and 150 JPEG photos. On some of the dives, the camera was switched to HD video mode to collect higher rate data. The video recording subsystem on the SX260HS includes an automatic exposure control making the recorded videos unsuitable for seawater spectral absorption analysis, but they do provide an excellent qualitative overview of the selective absorption effect with depth. Two videos from the final configuration of the color rig are posted online at YouTube:		The color rig's Canon SX260HS camera was programmed using the [http://chdk.wikia.com/wiki/CHDK CHDK] firmware to snap photos of the onboard Xrite color checker at an interval of approximately 2 seconds, limited by the camera's onboard processor. A single descent from the surface to 90 feet and back produces between 100 and 150 JPEG photos. On some of the dives, the camera was switched to HD video mode to collect higher rate data. The video recording subsystem on the SX260HS includes an automatic exposure control making the recorded videos unsuitable for seawater spectral absorption analysis, but they do provide an excellent qualitative overview of the selective absorption effect with depth. Two videos from the final configuration of the color rig are posted online at YouTube:

	[http://youtu.be/Hqa_7cUKV6M 85ft Dive Number 1 (with Salp capture on return!)]		[http://youtu.be/Hqa_7cUKV6M 85ft Dive Number 1 (with Salp capture on return!)]