NPorfilio - Revision history

imported>Psych2012: /* Appendix I */

2012-03-29T04:42:03Z

Appendix I

← Older revision		Revision as of 04:42, 29 March 2012
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	Imatest. http://www.imatest.com/		Imatest. http://www.imatest.com/

	~~= Appendix I =~~

	~~==Presentation Slides==~~
	~~"[http://white.stanford.edu/teach/images/a/ae/Nicholas_Porfilio_-_PSYCH221_Final_Presentation_vFinal.pdf Slides: An Analysis of Camera Image Quality: Nikon D5100 vs Sony Cyber-shot DSC-T700]"~~

imported>Psych2012: /* Conclusions */

2012-03-29T04:40:27Z

Conclusions

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	[[File:picsum.png \| thumb\|600px\|center\| Summary of Results]]		[[File:picsum.png \| thumb\|600px\|center\| Summary of Results]]

	Using these metrics, the Sony performed much better than expected. The Nikon had a better MTF by a considerable margin and a lower mean <math>\Delta</math>E, meaning that the camera produced sharper images with more accurate colors. The Sony had lower chromatic aberration and noise values, meaning it produced images with an insignificant amount of color fringing that were also less noisy. However, subjectively to the human eye the Nikon produced higher quality images of Stanford University's Memorial Church both during the day and at night.		Using these metrics, the Sony performed much better than expected. The Nikon had a better MTF by a considerable margin and a lower mean <math>\Delta</math>E, meaning that the camera produced sharper images with more accurate colors. The Sony had lower lateral chromatic aberration and noise values, meaning it produced images with an insignificant amount of color fringing that were also less noisy. However, subjectively to the human eye the Nikon produced higher quality images of Stanford University's Memorial Church both during the day and at night.

	There are several conclusions to be made.		There are several conclusions to be made.
	*1. The most surprising result was the noise measurement. Noise is a function of pixel size and the Nikon has a larger pixel size than the Sony which means that it can capture more photons and, consequently, detail. This result could mean that the noise measurement calculated in Imatest is not reflective of the resulting image.		*1. The most surprising result was the noise measurement. Noise is a function of pixel size and the Nikon has a larger pixel size than the Sony which means that it can capture more photons and, consequently, detail. This result could mean that the noise measurement calculated in Imatest is not reflective of the resulting image.
	*2. This could also mean that I made an error in my tests ~~either during~~ taking the images and/or processing them in Imatest. However, I did follow Imatest's instructions for capturing and analyzing the images so it's possible that the software only produces accurate results when used in labs under ~~tightly~~ controlled conditions.		*2. This could also mean that I made an error in my tests when taking the images and/or processing them in Imatest. However, I did follow Imatest's instructions for capturing and analyzing the images so it's possible that the software only produces accurate results when used in labs under highly controlled conditions.
	*3. This could also mean that the Sony actually does produce higher quality images with respect to noise and lateral chromatic aberration.		*3. This could also mean that the Sony actually does produce higher quality images with respect to noise and lateral chromatic aberration.
	*4. The results could be a function of my lens choice for the Nikon. Consumers can purchase a variety of lenses of different quality for the Nikon. The lens I used was a lens of modest quality, so perhaps I chose a poor lens with which to test.		*4. The results could be a function of my lens choice for the Nikon. Consumers can purchase a variety of lenses of different quality for the Nikon. The lens I used was a lens of modest quality, so perhaps I chose a poor lens with which to test.

	If I were to continue with this project in the future, I would reshoot all the test images and analyze them again in Imatest to ensure that my measurements were accurate. Then I would analyze those same images with another software, perhaps ISET. Next I would compare all the data and reassess my results.		If I were to continue with this project in the future, I would reshoot all the test images and analyze them again in Imatest to ensure that my measurements were accurate. Then I would analyze those same images with another image quality software package, perhaps ISET. Next I would compare all the data and reassess my results.

	= References =		= References =

imported>Psych2012: /* Methods */

2012-03-29T04:34:13Z

Methods

← Older revision		Revision as of 04:34, 29 March 2012
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	= Methods =		= Methods =
	I decided I needed both objective and subjective data to appropriately compare the two cameras. After all, even if all the quantitative measures say that one camera produces higher quality photos than another, it’s a moot point if the actual pictures do not look better to humans. Consequently, to get the quantitative data, I took a number of test shots with both cameras using the ISO 12233 and ~~MacBeth~~ ColorChecker and analyzed those in Imatest, a software package for testing digital image quality, on several different metrics discussed below. Then to get the subjective data I took a set of photographs of Memorial Church on Stanford University’s campus under a number of different lighting conditions. I then used all this data to compare the cameras and arrived at my conclusions.		I decided I needed both objective and subjective data to appropriately compare the two cameras. After all, even if all the quantitative measures say that one camera produces higher quality photos than another, it’s a moot point if the actual pictures do not look better to humans. Consequently, to get the quantitative data, I took a number of test shots with both cameras using the ISO 12233 and Macbeth ColorChecker and analyzed those in Imatest, a software package for testing digital image quality, on several different metrics discussed below. Then to get the subjective data I took a set of photographs of Memorial Church on Stanford University’s campus under a number of different lighting conditions. I then used all this data to compare the cameras and arrived at my conclusions.

	[[File:iso.png \| thumb\|300px\|center\| ISO 12233 Chart]]		[[File:iso.png \| thumb\|300px\|center\| ISO 12233 Chart]]

imported>Psych2012: /* Methods */

2012-03-29T04:33:52Z

Methods

← Older revision		Revision as of 04:33, 29 March 2012
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	= Methods =		= Methods =
	I decided I needed both objective and subjective data to appropriately compare the two cameras. After all, even if all the quantitative measures say that one camera produces higher quality photos than another, it’s a moot point if the actual pictures do not look better to humans. Consequently, to get the quantitative data, I took a number of test shots with both cameras using the ISO 12233 and MacBeth ColorChecker and analyzed those in Imatest, a software package for testing digital image quality, on several different metrics discussed below. Then to get the subjective data, I took a ~~couple~~ of ~~pictures~~ of Memorial Church on Stanford University’s campus under a number of different lighting conditions. I then used all this data to compare the cameras and ~~came up with~~ my conclusions.		I decided I needed both objective and subjective data to appropriately compare the two cameras. After all, even if all the quantitative measures say that one camera produces higher quality photos than another, it’s a moot point if the actual pictures do not look better to humans. Consequently, to get the quantitative data, I took a number of test shots with both cameras using the ISO 12233 and MacBeth ColorChecker and analyzed those in Imatest, a software package for testing digital image quality, on several different metrics discussed below. Then to get the subjective data I took a set of photographs of Memorial Church on Stanford University’s campus under a number of different lighting conditions. I then used all this data to compare the cameras and arrived at my conclusions.

	[[File:iso.png \| thumb\|300px\|center\| ISO 12233 Chart]]		[[File:iso.png \| thumb\|300px\|center\| ISO 12233 Chart]]

imported>Psych2012: /* Background */

2012-03-29T04:31:47Z

Background

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	<br>		<br>

	Many times image quality is also a function of camera price—many consumers expect a more expensive camera to deliver a higher quality image. But is this always the case? Does an expensive DSLR outperform a compact digital camera that is one-third its price? My project investigates two cameras on the market--the Nikon D5100 and the Sony Cyber-shot DSC-T700—using a subset of the factors discussed above and compares the quality of the ~~image~~ outputted by each.		Many times image quality is also a function of camera price—many consumers expect a more expensive camera to deliver a higher quality image. But is this always the case? Does an expensive DSLR outperform a compact digital camera that is one-third its price? My project investigates two cameras on the market--the Nikon D5100 and the Sony Cyber-shot DSC-T700—using a subset of the factors discussed above and compares the quality of the images outputted by each.

	A summary of each camera's specifications:		A summary of each camera's specifications:

imported>Psych2012: /* Background */

2012-03-29T04:30:46Z

Background

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	*'''Sensor:''' The sensor is an array of millions of tiny pixels that produce the final image. When you press your camera's shutter button and the exposure begins, each of these pixels has a photosite which is uncovered to collect and store photons in a cavity. Once the exposure finishes, the camera closes each of these photosites, and then tries to assess how many photons fell into each (''Cambridge in Colour''). Sharpness, distortion, vignetting, lateral chromatic aberration, noise, and dynamic range are the principal factors that can be measured at this stage (''Imatest'').		*'''Sensor:''' The sensor is an array of millions of tiny pixels that produce the final image. When you press your camera's shutter button and the exposure begins, each of these pixels has a photosite which is uncovered to collect and store photons in a cavity. Once the exposure finishes, the camera closes each of these photosites, and then tries to assess how many photons fell into each (''Cambridge in Colour''). Sharpness, distortion, vignetting, lateral chromatic aberration, noise, and dynamic range are the principal factors that can be measured at this stage (''Imatest'').

	*'''Image processing pipeline:''' The image processing pipeline is a set of digital adjustments made to the pre-processed image taken from the lens and sensor, and then transferred into the pipeline. It typically includes demosaicing, color correction, white balance, application of gamma and tonal response curves, sharpening, and noise reduction. The output of the pipeline may be compared to the minimally-processed lens and sensor measurements~~. However~~, the effect of the pipeline on subjective image quality can be highly scene and application-dependent, making it difficult to assign objective rankings (''Imatest'').		*'''Image processing pipeline:''' The image processing pipeline is a set of digital adjustments made to the pre-processed image taken from the lens and sensor, and then transferred into the pipeline. It typically includes demosaicing, color correction, white balance, application of gamma and tonal response curves, sharpening, and noise reduction. The output of the pipeline may be compared to the minimally-processed lens and sensor measurements, however, the effect of the pipeline on subjective image quality can be highly scene and application-dependent making it difficult to assign objective rankings (''Imatest'').

	<br>		<br>

imported>Psych2012: /* Background */

2012-03-29T04:28:53Z

Background

← Older revision		Revision as of 04:28, 29 March 2012
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	<br>		<br>
	[[File:Camera_pipeline.gif \| center \| The image pipeline. Courtesy of Dr. Karl Lenhardt, Bad Kreuznach]]		[[File:Camera_pipeline.gif \| center \| The image pipeline. Courtesy of Dr. Karl Lenhardt, Bad Kreuznach]]
	~~<br>~~<br>		<br>

	Many times image quality is also a function of camera price—many consumers expect a more expensive camera to deliver a higher quality image. But is this always the case? Does an expensive DSLR outperform a compact digital camera that is one-third its price? My project investigates two cameras on the market--the Nikon D5100 and the Sony Cyber-shot DSC-T700—using a subset of the factors discussed above and compares the quality of the image outputted by each.		Many times image quality is also a function of camera price—many consumers expect a more expensive camera to deliver a higher quality image. But is this always the case? Does an expensive DSLR outperform a compact digital camera that is one-third its price? My project investigates two cameras on the market--the Nikon D5100 and the Sony Cyber-shot DSC-T700—using a subset of the factors discussed above and compares the quality of the image outputted by each.

imported>Psych2012: /* Conclusions */

2012-03-29T04:27:51Z

Conclusions

← Older revision		Revision as of 04:27, 29 March 2012
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	*1. The most surprising result was the noise measurement. Noise is a function of pixel size and the Nikon has a larger pixel size than the Sony which means that it can capture more photons and, consequently, detail. This result could mean that the noise measurement calculated in Imatest is not reflective of the resulting image.		*1. The most surprising result was the noise measurement. Noise is a function of pixel size and the Nikon has a larger pixel size than the Sony which means that it can capture more photons and, consequently, detail. This result could mean that the noise measurement calculated in Imatest is not reflective of the resulting image.
	*2. This could also mean that I made an error in my tests either during taking the images and/or processing them in Imatest. However, I did follow Imatest's instructions for capturing and analyzing the images so it's possible that the software only produces accurate results when used in labs under tightly controlled conditions.		*2. This could also mean that I made an error in my tests either during taking the images and/or processing them in Imatest. However, I did follow Imatest's instructions for capturing and analyzing the images so it's possible that the software only produces accurate results when used in labs under tightly controlled conditions.
	*3. This could also mean that the Sony actually does produce higher quality images with respect to noise and lateral ~~color~~ aberration.		*3. This could also mean that the Sony actually does produce higher quality images with respect to noise and lateral chromatic aberration.
	*4. The results could be a function of my lens choice for the Nikon. Consumers can purchase a variety of lenses of different quality for the Nikon. The lens I used was a lens of modest quality, so perhaps I chose a poor lens with which to test.		*4. The results could be a function of my lens choice for the Nikon. Consumers can purchase a variety of lenses of different quality for the Nikon. The lens I used was a lens of modest quality, so perhaps I chose a poor lens with which to test.

	If I were to continue with this project in the future, I would reshoot all the test images and analyze them again in Imatest to ensure that my measurements were accurate. Then I would analyze those same images with another software, perhaps ISET. ~~Then~~ I would compare all the data and reassess my results.		If I were to continue with this project in the future, I would reshoot all the test images and analyze them again in Imatest to ensure that my measurements were accurate. Then I would analyze those same images with another software, perhaps ISET. Next I would compare all the data and reassess my results.

	= References =		= References =

imported>Psych2012: /* Background */

2012-03-29T02:04:57Z

Background

← Older revision		Revision as of 02:04, 29 March 2012
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	<br>		<br>
	[[File:Camera_pipeline.gif \| The image pipeline. Courtesy of Dr. Karl Lenhardt, Bad Kreuznach]]		[[File:Camera_pipeline.gif \| center \| The image pipeline. Courtesy of Dr. Karl Lenhardt, Bad Kreuznach]]
	<br><br>		<br><br>

imported>Psych2012: /* Background */

2012-03-29T02:03:37Z

Background

← Older revision		Revision as of 02:03, 29 March 2012
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	A summary of each camera's specifications:		A summary of each camera's specifications:

	[[File:~~cameraspecs~~.png \| thumb\|600px\|center\| Summary of Camera Specs]]		[[File:cameraspec.png \| thumb\|600px\|center\| Summary of Camera Specs]]
	<br>		<br>