DIGITAL IMAGE PROCESSING
1. Introduction about Digital Image processing
2. History about Digital Image Processing
3. Categories of Digital Image Processing
4. Image Viewing and Types
5. Digital Image Editing
6. Editing Programs and Digital Data Compression
7. Image Editor Features
By using Digital Image Processing we enhance the digital images and extract
information and features from the image. Digital Image Processing has become the most
common form of image processing, and it is generally used because it is not only the
most versatile method, but also the cheapest. This is one type of image processing and it
used for editing the digital images which are taken from the digital cameras. This
technology is more useful in the investigation in Crime Branch. Digital Image processing
has the advantages as a wider range of algorithm to be applied to the input data and can
avoid the problems such as build-up of noise and signal distortion during processing. For
this the NASA and US military have developed advanced computer software. By using
this software improve the clarity of and amount of detail visible in still and video images.
The main feature of this technology is Digital Image Editing. Image Editors are
provide the means for altering and improving images in an all most endless number of
time. They accept images in large variety of image formats. The other features of this
technology are Image Size Alteration, Cropping on Image, Removal of Noise and
unwanted elements, merging of images and finally color adjustments.
And in this paper we present categories of digital image processing, Image
Compression, Image viewing and Image types, and digital image editing, and finally
advantages and disadvantages of digital image processing.
Interest in digital image processing methods stems from two principal application
areas: improvement pictorial information for human interpretation; and processing of
image data for storage, transmission, and representation for autonomous machine
Image processing is enhancing image or extracting information or features from
an image. Any activity that transforms an input image into an output image. The
manipulation and alteration of images using computer software.
DIGITAL IMAGE PROCESSING :
Digital image processing is the use of computer to perform on. Digital image
processing has the same advantages (over analog image processing) as has (over analog
signal processing) -- it allows a much wider range of algorithms to be applied to the input
data, and can avoid problems such as the build-up of noise and signal distortion during
DIGITAL IMAGE :
A digital image is a representation of a two-dimensionalas a finite set of values,
called picture elements or pixels. Typically, the pixels are stored in computer memory as
a or a two-dimensional array of small integers. These values are often transmitted or
stored in a form.
Digital images can be by a variety of input devices and techniques, such as,
scanners, coordinate-measuring machines, seismographic profiling, airborne radar,
It is an image that was acquired through scanners or captured from digital
cameras. The most common kind of digital image processing is digital image editing.
Because of the computational load of dealing with images containing millions of
pixels, digital image processing was largely of academic interest until the 1970s, when
dedicated hardware became available that could process images in real time, for some
dedicated problems such as television standards conversion. As general-purpose
computers became faster, they started to take over the role of dedicated hardware for all
but the most specialized and compute-intensive operations.
With the fast computers and signal processors available in the 2000s, digital image
processing has become the most common form of image processing, and is generally
used because it is not only the most versatile method, but also the cheapest.
DIGITAL PROCESSING OF CAMERA IMAGES :
Images taken by popular digital cameras often need processing to improve their
quality, a distinct advantage digital cameras have over film cameras. The digital image
processing is done by special software programs that manipulate the images is many
ways. This process is performed in a "digital darkroom", which is not really a darkroom
as it is accomplished via a computer and keyboard.
REASONS FOR INTRODUING DIGITAL IMAGE PROCESSING:
Few types of evidence are more incriminating than a photograph or videotape that
places a suspect at a crime scene, whether or not it actually depicts the suspect
committing a criminal act. Ideally, the image will be clear, with all persons, settings, and
objects reliably identifiable. Unfortunately, though, that is not always the case, and the
photograph or video image may be grainy, blurry, of poor contrast, or even damaged in
In such cases, investigators may rely on computerized technology that enables
digital processing and enhancement of an image. The U.S. government, and in particular,
the military, the FBI, and the National Aeronautics and Space Agency (NASA), and
more recently, private technology firms, have developed advanced computer software
that can dramatically improve the clarity of and amount of detail visible in still and video
images. NASA, for example, used digital processing to analyze the video of the
HOW CAN WE PROCESS AN IMAGE ?
The first step in digital image processing is to transfer an image to a computer,
digitizing the image and turning it into a computer image file that can be stored in a
computer's memory or on a storage medium such as a hard disk or CD-ROM.
Digitization involves translating the image into a numerical code that can be understood
by a computer. It can be accomplished using a scanner or a video camera linked to a
frame grabber board in the computer.
The computer breaks down the image in to thousands of pixels. Pixels are the
smallest component of an image. They are the small dots in the horizontal lines across a
television screen. Each pixel is converted into a number that represents the brightness of
the dot. For a black-and-white image, the pixel represents different shades between total
black and full white. The computer can then adjust the pixels to enhance image quality.
CATEGORIES OF DIGITAL IMAGE PROCESSING:
The Three main categories of digital image processing are:
Image Compression is a mathematical technique used to reduce the amount of
computer memory needed to store a digital image. The computer discards
(rejects) some information, while retaining sufficient information to make the image
pleasing to the human eye.
Enhancement Image enhancement techniques can be used to modify the brightness
and contrast of an image, to remove blurriness, and to filter out some of the noise.
Using mathematical equations called algorithms, the computer applies each change to
either the whole image or targets a particular portion of the image.
For example, global contrast enhancement would affect the entire image, whereas
local contrast enhancement would improve the contrast of small details, such as a face
or a license plate on a vehicle. Some algorithms can remove background noise
without disturbing the key components of the image.
Measurement Extraction is used to gather useful information from an enhanced
The user can utilize different program to see the image. The GIF, JPEG and PNG
images can be seen simply using a web browser because they are the standard internet
image formats. The SVG format is more and more used in the web and is a standard W3C
IMAGE TYPES :
Digital images can be classified according to the number and nature of those
samples:The term digital image is also applied to data associated to points scattered over
a three-dimensional region, such as produced by tomographic equipment. In that case,
each datum is called a voxel.
TYPES OF IMAGES :
1. Binary Image :
A binary image is a digital image that has only two possible values for each
Binary images are also called bi-level or two-level.
A binary image is usually stored in memory as a bitmap, a packed array of bits.
A binary image is also a compiled version of source code in Linux and Unixes
2. Gray Scale: In computing, a grayscale or greyscale digital image is an image in which
the value of each pixel is a single sample.Grayscale images are distinct from black-and-
white images, which in the context of computer imaging are images with only two colors,
black and white; grayscale images have many shades of gray in between. In most
contexts other than digital imaging, however, the term "black and white" is used in place
For example, photography in shades of gray is typically called "black-and-
whitephotography". The term monochromatic in some digital imaging contexts is
synonymous with grayscale, and in some contexts synonymous with black-and-white.
3. Color Image: A (digital) color image is a digital image that includes color
information for each pixel.For visually acceptable results, it is necessary (and almost
sufficient) to provide three samples (color channels) for each pixel, which are interpreted
as coordinates in some color space. The RGB color space is commonly used in computer
displays, but other spaces such as YUV, HSV, and are often used in other contexts. Color
Image Representation : A color image is usually stored in memory as a raster map, a two-
dimensional array of small integer triplets; or (rarely) as three separate raster maps.
The same picture in three different color modes. The picture on the left is the original
photograph, in full color. The picture in the center is in grayscale. The picture on the
right is in black and white, or monochrome.
4. False Color : For military operations under a false flag, see false colors.
A "false color" image showing the Chesapeake Bay and the city of Baltimore.
This "true color" image shows the same region as the "false color" image above,
but uses true colors, e.g., the plants are shown in green.A false-color image is an image
that depicts a subject in colors that differ from human perception of the same subject.
Also known as a pseudo-color image, it is derived from a greyscale image by mapping
each pixel value to a color according to a table or function.. Although false-coloring
does not increase the information contents of the original image, it can make some
details more visible, by increasing the distance in color space between successive gray
For example, a photographic negative could be called a false-color image, since
it shows the complementary colors of its subject. However, the term "false-color" is
typically used to describe images whose colors represent measured intensities outside the
visible portion of the electromagnetic spectrum .False-color images are frequently used
for viewing satellite images, such as from weather satellites.
5. Multi Spectral Image: Multi-spectral images are images of the same object, taken in
different bands of visible or infrared region of electromagnetic continum. This is the main
type of images acquired by Remote sensing (RS) radiometers. Multi-spectral is the
opposite of panchromatic. Usually satelites have 3 to 7 or more radiometers. Each one
acquires one digiral image in a small band of visible spectra.
6. Thematic Image : Thematic images are usually image products of classification
processing of multispectral images of the earth surface. The classification process
differentiates types of surface such as land, water, forest, lake, structure etc.
DIGITAL IMAGE EDITING:
Digital image editing is the process of altering digital images, whether they be
digital photographs or other types of digitally represented images.
Specialised software programs called vector graphics editors or bitmap graphics
editors are the primary tools with which a user may manipulate, enhance, and transform
images. These editors are capable of editing images in many diverse ways.
BASICS OF DIGITAL IMAGE EDITING:
Bitmap images are stored in a computer in the form of a grid of picture elements
called pixels. These pixels contain the image's color and brightness information. Image
editors can change the pixels to enhance the image in many ways. The pixels can be
changed as a group, or individually, by the sophisticated algorithms within the image
IMAGE EDITING PROGRAMS:
Because of the popularity of digital cameras, image editing programs are readily
available. Minimal programs, that do such operations as rotating and cropping (image)s
are often provided within the digital camera itself, others are returned to the user on a
compact disc (CD) when images are processed at a discount store.
DIGITAL DATA COMPRESSION:
Many image file formats use data compression to reduce file size and save
storage spce. Digital compression of images may take place in the camera, or can be done
in the computer with the image editor. When images are stored in JPEG format,
compression has already taken place. Both cameras and computer programs allow the
user to set the level of compression.
Some compression algorithms are lossless, such as PNG, which means no image
quality is lost when the file is saved. The JPEG compression algorithm uses a lossy
format. The greater the compression, the lesser the quality. The JPEG algorithm utilizes
the way the brain and eyes perceive colour to make loss of detail less noticeable.
IMAGE EDITOR FEATURES:
Listed below are some of the most used capabilities of the better graphic
manipulation programs. The list is by no means all inclusive. There are a myriad of
choices associated with the application of most of these features.
Image Size Alteration: Image editors can resize an image, making it larger, or
smaller. High image resolution cameras can produce large images which are
often reduced in size for Internet use. Image editor programs use a mathematical
process called re-sampling to calculate new pixel values whose spacing is larger
or smaller than the original pixel values..
Cropping An Image: Digital editors are used to crop images. Cropping creates a
new image by removing a desired rectangular portion from the image being cropped.
The unwanted part of the image is discarded. Image cropping does not reduce the
resolution of the area croppe
Noise Removal: Image editors may feature a number of algorithms which can
add or remove noise in an image. JPEG artifacts can be removed; dust &
scratches can be removed and an image can be despeckled. Noise tends to invade
images when pictures are taken in low light settings.
Removal Of Unwanted Elements: Most image editors can be used to remove
unwanted branches, etc, using a "clone" tool.
Original Removal of branch at the top of image
Selective Color Change: Image editors have the ability to selectively change the
color of specific items in an image.
An example of selective color change, the original is on the right.
Merging Of Images: Many graphics applications are capable of merging one or more
individual images into a single picture. The orientation and placement of each image can be
controlled. The two images shown here were once individual studio portraits.
John and Bertha Phillips - 1910
Special Effects: Image editors usually have a list of special effects that can create
unusual results. Images may be skewed and distorted in various ways. Scores of
special effects can be applied to an image which include various forms of distortion,
artistic effects, geometric and texture effects, and combinations thereof.
An example of some special effects that can be added to a picture.
Change Color Depth: It is possible, using software, to change the color depth of
images. Common color depths are 2, 16, 256, and 16 million colors. The JPEG
and PNG image formats are capable of storing 16.7 million colors (equal to 256
luminance values per color channel). In addition, grayscale images of 8 bits or
less can be created, usually via conversion and downsampling from a full color
An example of converting an image from color to grayscale.
Lens Correction: Photo manipulation packages have functions to correct images for
various lens distortions inclduing pincushion, fisheye and barrel distortions. The
corrections are subtle, but can improve the appearance of some photographs.
Contrast Change And Brightening: Image editors have provisions to change the
contrast of images and brighten or darken the image. Many an underexposed image can be
improved by using this feature. only pixels below a particular luminosity threshold are
brightened, thereby brightening underexposed shadows without affecting the rest of the
Sharpening And Softening Images: Graphics programs can be used to both
sharpen and blur images in a number of ways. Edge enhancement is an extremely
common technique used to make images appear sharper, although many purists frown
on the end result as less natural-looking.
Color Adjustments: The color of images can be altered in a variety of ways. The
color balance can be improved, colors and be faded in and out, and tones can be
changed. Special effects, like sepia and grayscale can be added to an image.
1. One of the biggest advantages of digital imaging is the ability of the operator to
manipulate the pixel shades to correct image density and contrast, is called Post-
Processing. And perform other processing functions that could result in improved
diagnosis and fewer repeated examinations.
2. Digital imaging allows the electronic transmission of images to third-party
providers, referring dentists, consultants, and insurance carriers via a modem.
3. Digital imaging is also environmentally friendly since it does not require chemical
processing. It is well known that used film processing chemicals contaminate the
water supply system with harmful metals such as the silver found in used fixer
4. Radiation dose reduction is also a benefit derived from the use of digital systems.
Some manufacturers have claimed a 90% decrease in radiation exposure, but the
real savings depend on comparisons.
There are also disadvantages associated with the use of digital systems.
1. The initial cost can be high depending on the system used, the number of
detectors purchased, etc.
2. Competency using the software can take time to master depending on the level of
computer literacy of team members. Finally, since digital imaging in dentistry is
not standardized, professionals are unable to exchange information without going
through an intermediary process.
1.Remote Sensing:Natural resources survey and management;estimation relatedto
agriculture,forestry;environment and pollution;etc.
2.Astronomy:Restoration of images suffering from geometrical distortions; computing
close up picture of planetary surfaces;etc.
3.Militaty applicatons: Missile guidance and detection; target identification.
4.Criminology: Finger print identification; face registration and matching; forensic
5.Medicine: Processing chest x-rays; radiology; detection of tumours; etc.
6.Image Transmission and Storage Applications: Transmission of Facsimile
images; video conferencing; etc.
Image editors provide the means for altering and improving images in an almost
endless number of ways. They accept images in a large variety of image formats, and
after changes are made they allow the changed image to be saved in any number of image
formats, at almost any size, and in varying degrees of compression. Most serious digital
camera users will find the facilities of an image editor indispensable.
It holds possibility of developing the ultimate machine which can perform
visual functions of all living beings.
DIGITAL IMAGE PROCESSING
1. Introduction about Digital Image processing
2. Definition of Digital Image Processing
4. Image Viewing and Types
5. Stages in Image Processing
6. Components of Image Processing
7. Categories of Digital Image Processing
8. Digital Image Editing
9. Image Editor Features
10. Advantages & Disadvantages
Enhancing an Image and drawing Information or features
from an Image.
Digital Image Processing:
Processing 2-d Digital Images using a DigitalComputer.
Receiving and analyzing visual information.
2-d representation of a scene in digital form.
Digital Image Types:
Gray Scale Image
Stages in Image Processing:
1. Discretization and Represenation
Components in Image Processing:
Image Sensor (Image Sensing)
Display Unit (Displaying)
Printer ( “ )
Categories of DIP:
There are many categories of DIP. Most important of them
Digital Image Editing:
Alter Digital Images.
Image Size Alteration
Cropping An Image
Removal Of Unwanted Elements
Selective Color Change
Merging Of Images
Change Color Depth
Contrast Change And Brightening
Sharpening And Softening Images
Image Transmission and Storage Applications
RADAR and SONAR(Military Applications)