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MC0086- DIGITAL IMAGE PROCESSING

Ques 1:-Explain any two fields that use digital image processing?

Ans:-

Gammaray Imaging

Major uses of imaging based on gamma rays include nuclear medicine and astronomical observations.

In nuclear medicine, the approach is to inject a patient with a radioactive isotope that emits gamma rays

as it decays.

Images are produced from the emissions collected by gamma ray detectors.

X - ray Imaging

It is oldest sources of EM radiation used for imaging.

The best known use of X-rays is medical diagnostics.

X-rays for medical and industrial imaging are generated using an X-ray tube, which is a vacuum tube

with a cathode and anode.

Angiography is another major application in an area called contrast enhancement radiography.

Ques 2:-Explain the properties and uses of electromagnetic spectrum.?

Ans:-

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Ques 3:-Explain different Photographic process models?

Ans:-There are many different types of materials and chemical processes that have been utilized for

photographic image recording. No attempt is made here either to survey the field of photography or to

deeply investigate the physics of photography.

Monochromatic Photography

The most common material for photographic image recording is silver halide emulsion, depicted.

In this material, silver halide grains are suspended in a transparent layer of gelatin that is deposited on a

glass, acetate or paper backing. If the backing is transparent, a transparency can be produced, and if the

backing is a white paper, a reflection print can be obtained. When light strikes a grain, an

electrochemical conversion process occurs, and part of the grain is converted to metallic silver. A

development center is then said to exist in the grain. In the development process, a chemical developing

agent causes grains with partial silver content to be converted entirely to metallic silver. Next, the film is

fixed by chemically removing unexposed grains. The photographic process described above is called anonreversal process. It produces a negative image in the sense that the silver density is inversely

proportional to the exposing light. A positive reflection print of an image can be obtained in a two-stage

process with nonreversal materials. First, a negative transparency is produced, and then the negative

transparency is illuminated to expose negative reflection print paper. The resulting silver density on the

developed paper is then proportional to the light intensity that exposed the negative transparency.

Color PhotographyModern color photography systems utilize an integral tripack film, as illustrated in Fig. 5.4, to produce

positive or negative transparencies. In a cross section of this film, the first layer is a silver halideemulsion sensitive to blue light. A yellow filter following the blue emulsion prevents blue light from

passing through to the green and red silver emulsions that follow in consecutive layers and are naturally

sensitive to blue light. A transparent base supports the emulsion layers. Upon development, the blue

emulsion layer is converted into a yellow dye transparency whose dye concentration is proportional to

the blue exposure for a negative transparency and inversely proportional for a positive transparency.

Similarly, the green and red emulsion layers become magenta and cyan dye layers, respectively.

Color prints can be obtained by a variety of processes. The most common technique is to produce a

positive print from a color negative transparency onto nonreversal color paper. In the establishment of a

mathematical model of the color photographic process, each emulsion layer can be considered to reactto light as does an emulsion layer of a monochrome photographic material. To a first approximation, this

assumption is correct.

Ques 4:-Define and explain Dilation and Erosion concept.

Ans:- With dilation, an object grows uniformly in spatial extent. Generalized dilation is expressed

symbolically as

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G(j, k) = F(j, k)H(j, k)where F(j, k), for 1 j, k N is a binary-valued image and H(j, k) for , 1 j, k L, where L is an odd integer,

is a binary-valued array called a structuring element. For notational simplicity, F(j,k) and H(j,k) are

assumed to be square arrays. Generalized dilation can be defined mathematically and implemented in

several ways. The Minkowski addition definition is

It states that G(j,k) is formed by the union of all translates of F(j,k) with respect to itself in which the

translation distance is the row and column index of pixels of H(j,k) that is a logical 1. illustrates the

concept.

Erosion

With erosion an object shrinks uniformly. Generalized erosion is expressed symbolically as

G (j, k) = F(j, k)H (j, k)Where H(j,k) is an odd size L * L structuring element. Generalized erosion is defined to be

The meaning of this relation is that erosion of F(j,k) by H(j,k) is the intersection of all translates of F(j,k)

in which the translation distance is the row and column index of pixels of H(j,k) that are in the logical

one state. Fig. 6.4 illustrates this. Fig. 6.5 illustrates generalized dilation and erosion.

Ques5:-Which are the two quantitative approaches used for the evaluation of image features?Explain.

Ans:-Image Feature Evaluation There are two quantitative approaches to the evaluation of image

features: prototype performance and figure of merit. In the prototype performance approach for image

classification, a prototype image with regions (segments) that have been independently categorized is

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classified by a classification procedure using various image features to be evaluated. The classification

error is then measured for each feature set. The best set of features is, of course, that which results in

the least classification error. The prototype performance approach for image segmentation is similar in

nature. A prototype image with independently identified regions is segmented by a segmentation

procedure using a test set of features. Then, the detected segments are compared to the known

segments, and the segmentation error is evaluated. The problems associated with the prototype

performance methods of feature evaluation are the integrity of the prototype data and the fact that the

performance indication is dependent not only on the quality of the features but also on the classification

or segmentation ability of the classifier or segmenter. The figure-of-merit approach to feature

evaluation involves the establishment of some functional distance measurements between sets of

image features such that a large distance implies a low classification error, and vice versa. Faugeras and

Pratt have utilized the Bhattacharyya distance figure-of-merit for texture feature evaluation. The

method should be extensible for other features as well. The Bhattacharyya distance (B-distance for

simplicity) is a scalar function of the probability densities of features of a pair of classes defined as

where x denotes a vector containing individual image feature measurements with conditional density p

(x | S1).

Ques 6:- Explain about the Region Splitting and merging with example?

Ans:-Region Splitting and MergingSub-divide an image into a set of disjoint regions and then merge and/or split the regions inan attempt to satisfy the conditions stated in section 10.3.1.

Let R represent the entire image and select predicate P. One approach for segmenting R is to

subdivide it successively into smaller and smaller quadrant regions so that, for ant region, P() =

TRUE. We start with the entire region. If then the image is divided into quadrants. If P is FALSE for

any quadrant, we subdivide that quadrant into sub quadrants, and so on. This particular splitting

technique has a convenient representation in the form of a so called quad tree (that is, a tree in

which nodes have exactly four descendants), as shown in Fig. (10.3.3) 10.4. The root of the tree

corresponds to the entire image and that each node corresponds to a subdivision. In this case, only

was sub divided further.

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