Navigation Links
Not All Bits Are Created Equal

Tatiana A. Sedova, Bio-Rad Laboratories,
2000 Alfred Nobel Drive, Hercules, CA 94547 USA


Manipulating Bits A Gray Area
Scientific data collected with an imaging device can be true or altered. Alteration of imaged data is used to create an impression of more data retrieved than is actually collected. Altered data can be accomplished either through software or through digitization. Both methods are able to compress or spread out true data, but the bottom line is that the true data is not accurately represented after alteration.

In a charge-coupled device (CCD) camera, bits represent the range of quantitative data obtained from an image. The data is recorded in distinct shades of gray ranging from absolute white to absolute black. The number of shades of gray is denoted by the bit number of a camera; an 8-bit camera has 28, or 256, distinct shades of gray, a 12-bit camera has 4,096 (212) shades of gray, and a 16-bit camera has 65,536 (216) shades of gray. Thus, a 16-bit camera is said to have a greater dynamic range than the 12- or 8-bit camera. For reference, the human eye is capable of distinguishing 64 levels of gray (that is, 26 ), whereas the computer monitor screen displays 256 levels (28 ); in other words, any image displayed by a computer will be 8-bit, but even though more data is available, we can only distinguish a quarter of it (Figure 1).

A higher-bit system is able to distinguish minute diff e rences in imaged data better than a lower-bit system. A 16-bit digital image is much deeper than a 12-bit and is there f o re more beneficial for quantitative analysis. This ability corresponds to the ratio of the number of gray levels between the two systems.

In a 12-bit camera, a change of 1 level of gray would correspond to a change of 16 (216/212=24) levels of gray in a 16-bit camera. Obviously a higher-bit system is more desirable, since the data output is much more sensitive to subtle differences within an image.


Alteration By Software with File Generation
The first and simplest way in which imaged data can be boosted is via software, which takes lower-bit data and converts it to a higher-bit file, and is known as x-bit file generation. Creating a higher-bit file distorts the actual data obtained. For example, in an image acquired with a 12-bit camera, one of the pixels might have a value of 2,000 on the gray-level scale with its range of 0 to 4,095. Converting that pixel into a 16-bit file would convert its value to 32,000 in a range of 0 to 65,535. This newly created image is read out as an impressive 16-bit file, but the data is falsely represented the file cannot contain any more information than the capacity of the 12-bit camera (Figure 2).


CCD Collection and Transfer
Another manner in which larger-bit images are generated is dependent on the way a CCD camera collects and transfers data. A CCD chip measures light intensity by generating and collecting electrons. The best analogy for a CCD chip is an array of electron-filled buckets called pixels (Figure 3). Each bucket has a certain depth; some are shallow and hold 15,000 electrons, others are able to contain 40,000 electrons, and some, up to 300,000 electrons. This capacity is the well depth of the chip.

CCD chip designs govern the capacity of their buckets. The two designs most commonly seen are the full-frame sensor and the interline chip. The first, the full-frame sensor (Figure 3), is a straightforward array of pixels of various capacities (well depth), and widths (pixel size). The other design, the interline chip, introduces a feature that is beneficial in the transfer rate but limits the pixel size. The interline chip, although also laid out as an array of pixels, includes transfer sections located next to each row of pixels. Due to its layout, the parameters of each pixel are restricted. It is easy to see the limitations of the bucket size in the architecture of the interline chip. Construction of a megapixel CCD chip with pixels adequately large for high-quality data acquisition is technically possible; however, the chip would be very large and there fore very expensive. As a result, such a chip is not being offered commercially.

Once charge has accumulated within the pixels, it is transferre d out of the pixels for conversion into data. An analog-to-digital converter, or digitizer, translates the number of electro n s into digital numerical data. The digitizer determines the bit number of the output. That is, a 12-bit digitizer will produce a 12-bit image and a 16-bit digitizer a 16-bit image. To ensure accurate data collection, it is crucial to select a digitizer that appropriately matches the well depth of the pixels. For a 12-bit digitizer with 4,096 levels, the best well depth would have a capacity of 4,096 electrons; that is, for each collected electron, the data would correspond literally to a gray level. For example, if a pixel contained 2,000 electrons, the digital readout would be at the 2,000th gray level.


Noise
A factor that needs to be considered for accurate digitization is noise. Noise is added signal from sources such as dark current, shot noise, and read noise, that is not part of the signal from the object being imaged. Noise reduces the dynamic range, which is the ratio of well depth to noise:

For example, a system with a well depth of 40,000 electrons and with a noise of 10 electrons would only have a dynamic range of 4,000 electrons. (Other examples are given in the table.)

With all this in mind, the true dynamic range and the systems digitizer together determine the true bit output. Following the above example, the best output would be as follows: For a CCD chip with a calculated dynamic range of 4,000 electrons, a 12-bit digitizer would allocate that to 4,096 gray levels. If the same information were to be translated by an 8-bit digitizer, the 4,000 electrons would need to be compressed into 256 gray levels, causing loss of information. Conversely, creating seemingly impressive data by the use of a 16-bit digitizer distorts the true data obtained into 65,536 gray levels, while adding no additional information.


Bio-Rads Approach
Bio-Rads imaging instruments provide customers the truest data possible. We understand that true data is the most important part of your research. All of our CCD camera systems output data without computer-aided enhancements or digitization mismatching, ensuring accurate data acquisition. We acquire the best data by using large well depths and reducing noise. By clearly stating an ambient or true cooling method, and with back thinning (where appropriate), we excel at lowering noise. To maximize the usefulness of your imaging systems, be aware of where your bits are coming from.

Figures reprinted or modified with permission of Roper Scientific, from the technical note Every Bit Counts, 1999.


Well Depth Comparison


back to top
'"/>

Source:


Page: All 1 2 3 4 5

Related biology technology :

1. Identification of Differentially Expressed Gene Products with the CastAway System*
2. An Optimal DNA Microarray Substrate for the Identification of Fetal and Somatic Liver Stem Cells of the Rat
3. Identification of Low-Level Oxidation Products in Calmodulin Using NanoSpray Ion Trap Mass Spectrometry
4. Detection and Identification of Phosphorylation Sites in Proteins Using LC/MS/MS with Neutral Fragment Loss Mapping
5. Protect RNA and Improve Target Cell Identification
6. Identification of Disease Causing Mutations in Phenylketonuria by Denaturing Gradient Gel Electrophoresis Using the DCode System
7. Identification of cells in S phase using the Cell Proliferation Fluorescence Kit and IN Cell Analyzer 1000
8. Identification of Insecticides and Herbicides by LC/MS/MS Using the API 2000 LC/MS/MS System
9. Identification of Phase I and Phase II Metabolites of Buspirone on the Q TRAP LC/MS/MS System
10. ESR1 Gene Expression in Oncology and Metabolic Diseases Using the ASCENTATM System Target Validation and Identification of Novel Disease Indications
11. High-Throughput System Generates Ultra-Pure PCR Products Suitable for All Applications
Post Your Comments:
*Name:
*Comment:
*Email:
TAG: Not All Bits Are Created Equal

(Date:9/17/2014)... 17, 2014 RXi Pharmaceuticals Corporation (NASDAQ: ... on discovering, developing and commercializing innovative therapies addressing ... that it has been granted a patent by ... its unique delivery system for delivering its "original" ... for the treatment of diseases with an inflammatory ...
(Date:9/17/2014)... Cary, N.C. (PRWEB) September 17, 2014 ... solutions that advances science and healthcare, has renewed its ... term. , As part of the agreement, Personify will ... with a sustained emphasis on recruitment analytics, including time-to-fill, ... decision to renew our agreement with Personify was based ...
(Date:9/17/2014)... , September 17, 2014 ... of action from a truly novel class ... MGB Biopharma, a biopharmaceutical company developing ... today that it has secured £4.0m ($6.4m) ... antibacterial, MGB-BP-3, against a range of Gram-positive ...
(Date:9/17/2014)... Wilmington, DE (PRWEB) September 17, 2014 ... profit organization committed to lowering the barriers to ... has announced the appointment of Carmen Nitsche as ... organization looks to expand its global reach. , ... she was Vice President, Corporate Development. At Accelrys, ...
Breaking Biology Technology:RXi Pharmaceuticals Strengthens Intellectual Property Portfolio 2RXi Pharmaceuticals Strengthens Intellectual Property Portfolio 3RXi Pharmaceuticals Strengthens Intellectual Property Portfolio 4Beckman Coulter Signs 3-year RPO Contract with Personify 2Beckman Coulter Signs 3-year RPO Contract with Personify 3MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 2MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 3MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 4MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 5MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 6MGB Biopharma Secures £4.0m ($6.4m) to Advance its Novel Lead Antibacterial, MGB-BP-3, into Clinical Development 7Pistoia Alliance Expands Business Development with Appointment of Carmen Nitsche 2
... SAN DIEGO, July 28, 2011 Gen-Probe Incorporated (NASDAQ: ... quarter of 2011, with total revenues of $135.9 million and ... "Gen-Probe posted record sales of APTIMA women,s health products in ... blood screening revenue to decline compared to strong sales a ...
... Neurocrine Biosciences, Inc. (NASDAQ: NBIX ) today announced ... the second quarter of 2011, the Company reported net income of ... of $5.2 million, or $0.09 loss per share, for the same ... the Company reported net income of $4.9 million, or $0.09 per ...
... ITMN ) today announced that it will release its ... A live conference call and webcast will be hosted by ... discuss business highlights and financial results for the second quarter ... the live teleconference, dial 888-567-5125 (U.S.) or 706-643-9223 (international), conference ...
Cached Biology Technology:Gen-Probe Reports Financial Results for the Second Quarter of 2011 2Gen-Probe Reports Financial Results for the Second Quarter of 2011 3Gen-Probe Reports Financial Results for the Second Quarter of 2011 4Gen-Probe Reports Financial Results for the Second Quarter of 2011 5Gen-Probe Reports Financial Results for the Second Quarter of 2011 6Gen-Probe Reports Financial Results for the Second Quarter of 2011 7Gen-Probe Reports Financial Results for the Second Quarter of 2011 8Gen-Probe Reports Financial Results for the Second Quarter of 2011 9Gen-Probe Reports Financial Results for the Second Quarter of 2011 10Gen-Probe Reports Financial Results for the Second Quarter of 2011 11Gen-Probe Reports Financial Results for the Second Quarter of 2011 12Gen-Probe Reports Financial Results for the Second Quarter of 2011 13Gen-Probe Reports Financial Results for the Second Quarter of 2011 14Neurocrine Biosciences Reports Second Quarter 2011 Results 2Neurocrine Biosciences Reports Second Quarter 2011 Results 3Neurocrine Biosciences Reports Second Quarter 2011 Results 4Neurocrine Biosciences Reports Second Quarter 2011 Results 5Neurocrine Biosciences Reports Second Quarter 2011 Results 6Neurocrine Biosciences Reports Second Quarter 2011 Results 7InterMune to Release Second Quarter Financial Results on August 4 2
(Date:9/16/2014)... severe maternal morbidity amongst women in Australia is ... study published today (17 September) in BJOG: ... , Australians generally enjoy high standards of living; ... exist, in particular between indigenous and non indigenous ... the independent impact of socioeconomic position on severe ...
(Date:9/16/2014)... 36 Pit Fire began on September 13, 2014. The ... It is currently over 2,300 acres in size and is ... 36 Pit Fire was calm Monday night due to higher ... an anchor point and beginning to construct a fireline on ... following resources are working on the fire: , 7 20-person ...
(Date:9/16/2014)... the dinosaurs 66 million years ago decimated the evergreens ... than their deciduous peers, according to a study led ... journal PLOS Biology . , Applying biomechanical ... leaves of angiosperms flowering plants excluding conifers ... of a diverse plant community thriving during a 2.2 ...
Breaking Biology News(10 mins):New study examines the impact of socioeconomic position & maternal morbidity in Australia 2New study examines the impact of socioeconomic position & maternal morbidity in Australia 3Meteorite that doomed dinosaurs remade forests 2Meteorite that doomed dinosaurs remade forests 3Meteorite that doomed dinosaurs remade forests 4
... Biobanks are repositories for tissue samples, usually in ... from surgical procedures. These samples are collected and used ... linked to personal health information regarding the sample donor. ... researchers who want to use them face important questions ...
... The Life Sciences Discovery Fund (LSDF) today announced awards ... therapies and key resources for medical researchers and health-care ... the three programs. The programs will be led ... across the state. Dr. David Flum will work with ...
... MADISON, WI, JUNE 28, 2011 -- The ... provides information needed to sustainably manage agroforestry systems. ... increase yields and also reduce financial and environmental ... that allows for site-specific evaluation of nutrient-production imbalances ...
Cached Biology News:Public prefers limited informed consent process for biobanks 2Public prefers limited informed consent process for biobanks 3Life Sciences Discovery Fund helps launch 3 programs to advance health research and development 2Analyzing agroforestry management 2
... MKK6 (phospho S207) ( Abpromise ... Antigen: Synthetic phosphopeptide derived ... site of Serine 207 (V-D-S P ... ID: 5608 ...
Rabbit polyclonal to Reptin/TIP49B/RUVB2 ( Abpromise for all tested applications). Antigen: Synthetic peptide (Human) Entrez Gene ID: 10856 Swiss Protein ID: Q6FIB9...
Mouse monoclonal [1Q17] to TGE Virus peplomer ( Abpromise for all tested applications)....
Goat polyclonal to ORC2L ( Abpromise for all tested applications). entrezGeneID: 4999 SwissProtID: Q13416...
Biology Products: