<< Chapter < Page Chapter >> Page >
Process of converting an image of handwritten digits into a standardized format.

Give your digits!: image processing

When an image is acquired, its size and dimensions will vary. Since the database we use is in grayscale and 28x28 pixels large, each input image must be processed so that it also has the same dimensions.

Acquired Image

Convert to grayscale

The acquired image is in RGB format, where each pixel in the image consists of 3 components: the intensity of red, green and blue. Grayscale consists of a single intensity value for each pixel. Therefore, to change each input image to grayscale, we will use the Matlab operator, rgb2gray().

Edge detection

The only information of interest in the input image are the intensities of the actual digits, rather than the intensities of the background. Edge detection will remove background noise and filter the image so that only areas of high contrast (which is the shape of the handwritten digits) remain. The figure below shows the result of applying a simple Sobel edge detector using the edge() command with the threshold set to default.

Result of edge detection with sobel operator.

Dilation: morphological operator

A morphological operator such as dilation processes an image so that its shape is changed in some way. Dilation expands all the boundaries of objects in the image. Dilation in this case also serves to connect any disconnected regions of an outline together. Through the imdilate() command, we can specify how to expand the digit outlines by a structuring element. Depending on the shape of the structuring element, the appearance of the image will change. The ‘ball’ structuring element will be a good choice, since this uses a gradient to make the digits look smoother and rounded out, similar to the way the data is normalized. Depending on how large the digits are written, the size of the structuring element will need adjustment – larger images require a larger structuring element in order to fill more of the outline. In order to get consistent results from dilation, we made sure all writing samples were approximately the same size. The figure below shows the result of dilation.

Dilation of Digit Outlines

Separating individual digits

Now that the only identifiable regions in the image are the digits themselves, the Matlab operator regionprops() with the ‘boundingbox’ option, we will be able to separate the digits into individual images.

Connected regions are identified by ‘boundingbox’

Resize and normalize image

Most input images are much larger than needed and must be rescaled and centered to 28x28 pixels. Imresize() scales the image to 20x20 pixels. Afterwards, zero padding adds zeros to each side of the image, resulting in a 28x28 pixel image. The input image is now standardized and ready to be identified.

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
I rally confuse this number And equations too I need exactly help
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Elec 301 projects fall 2008. OpenStax CNX. Jan 22, 2009 Download for free at http://cnx.org/content/col10633/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Elec 301 projects fall 2008' conversation and receive update notifications?