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:7/24/2014)... (PRWEB) July 24, 2014 2014 ... Sulphate Industry” is a professional and in-depth research ... introduces Potassium Sulphate basic information, including its ... industry overview. This research covers the international market ... global industry analysis covering macroeconomic environment & economic ...
(Date:7/24/2014)... 24, 2014 1000 balances – 4 ... on customers’ weighing needs and expertly narrows down the ... balances, scales or even terminals. , First, select ... weight (or select readability instead) and define the accuracy ... selection criteria narrows down the list to models that ...
(Date:7/24/2014)... -- Spherix Incorporated (SPEX) -- an intellectual property development company ... today announced that the Company will issue a business ... Monday, August 18, 2014 for shareholders. Management has scheduled ... August 18, 2014 to discuss the company,s progress to ... Anthony Hayes . Following prepared remarks, management ...
(Date:7/24/2014)... July 24, 2014 The patent ... molecular diagnostic test results. It also enables true ... the validation and reporting of high profile assays ... is a rapidly growing area of biotechnology that ... predisposition, cancer, and companion diagnostics in personalized medicine. ...
Breaking Biology Technology:Potassium Sulphate Market & SHMP Industry 2014 (Global, China) Analysis Now Available at DeepResearchReports.com 2Potassium Sulphate Market & SHMP Industry 2014 (Global, China) Analysis Now Available at DeepResearchReports.com 3Potassium Sulphate Market & SHMP Industry 2014 (Global, China) Analysis Now Available at DeepResearchReports.com 4Spherix Schedules Shareholder Update Call 2New DNA-barcode Patent Virtually Eliminates False Test Results and Sample Mix-up 2
...  Today, the Global Probiotics Council (GPC), a committee formed ... launch of the fifth annual Young Investigator Grant for ... in the amount of $50,000, to promising young researchers. ... the role of probiotics and gastrointestinal microbiota in health ...
... Arcion Therapeutics, a clinical stage biotechnology company developing ... received notice of allowance for a US Patent for ... ARC-2022 is being developed by Arcion for pain associated ... has been evaluated in a single-dose Phase 1 pharmacokinetic ...
... Jan. 4, 2012  Verify Brand™ announces the release ... 4.0 software. VB Enterprise 4.0 is a suite ... client and mobile software applications that enable comprehensive ... Trace® across the supply chain. VB Enterprise ...
Cached Biology Technology:Fifth Cycle of Probiotics & Microbiota Research Grant Announced 2Fifth Cycle of Probiotics & Microbiota Research Grant Announced 3Fifth Cycle of Probiotics & Microbiota Research Grant Announced 4Arcion Receives Notice of Allowance for US Patent for Novel Topical Lidocaine Formulation for Pain 2Verify Brand™ Announces the Release of VB Enterprise 4.0 2
(Date:7/24/2014)... electric cars ply silent freeways, solar panels blanket rooftops ... earth, from howling winds and from the blazing desert ... is technically and economically feasible to convert California,s all-purpose ... Published in Energy , the plan shows the ... in California that could create tens of thousands of ...
(Date:7/24/2014)... brewery has its own microbial terroir, meaning the microbial ... found in the product, creating the final flavor according ... Applied and Environmental Microbiology . This is the ... a sake brewery. , Many sake makers inoculate ... A. Mills of the University of California, Davis, but ...
(Date:7/24/2014)... low vision specialist at The University of Texas Health ... awarded a grant to help Harris County residents whose ... surgery. , Even with corrective lenses, many people with ... are a variety of low vision devices, such as ... vision loss. , Iyer is using the three-year, $164,645 ...
Breaking Biology News(10 mins):Stanford study shows how to power California with wind, water and sun 2Stanford study shows how to power California with wind, water and sun 3Stanford study shows how to power California with wind, water and sun 4The microbes make the sake brewery 2UTHealth Dr. Bhavani Iyer awarded low vision grant 2
... turned off or left on in healthy ... common cancers and maybe help avoid them, Medical College ... alterations, called DNA methylation, in the body,s basic building ... and their cancerous counterpart to find telltale patterns that ...
... A new study finds that most older long-term cancer survivors ... health habits. The study also reveals that those survivors ... health and quality of life. Published in the September 1, ... the American Cancer Society, the research indicates that greater efforts ...
... The results of a national assessment of indoor location ... announced at Worcester Polytechnic Institute (WPI) during the 2009 ... Emergency Responders, which runs from Aug. 3 to 4. ... with funding from the Department of Homeland Security and ...
Cached Biology News:Cancer's distinctive pattern of gene expression could aid early screening and prevention 2Cancer's distinctive pattern of gene expression could aid early screening and prevention 3Cancer's distinctive pattern of gene expression could aid early screening and prevention 4Most older long-term cancer survivors have poor health habits 2Results of national assessment of first responder location systems to be announced Aug. 3 2Results of national assessment of first responder location systems to be announced Aug. 3 3Results of national assessment of first responder location systems to be announced Aug. 3 4
For the quantitative determination of cyclic AMP (cAMP) concentrations in cell culture supernates, serum, plasma, saliva, urine and cell lysates....
FRACTALKINE [Human] (Recombinant)...
... head automatically rises at the end of determination; triple-point calibration verification; refrigerator eliminates need for pumps and bath ... * ... ... ...
... The Luminex® 200 System with ... for developing single and multi-analyte assays ... contains the new, powerful user friendly ... user can design specific templates for ...
Biology Products: