Project Poster

1. ADVANCEDDOCUMENTSCANNER
WITHDIGITALMOSAIC
Sameer Desai, Steven Ghodke & Sidharth Kulkarni | Dept. of E&TC
samades@gmail.com, steven.ghodke@gmail.com, sksidforyou55@gmail.com
Project Supervisor: Prof. Vinayak B Kulkarni
Objectives
Our main objective is to achieve image scan
through phototransistor array, instead of the
usual CCD methodology. We also aim to include
the feature of creation of a digital mosaic from
multiple scanned pictures, which can have ap-
plication or use in scanning very big sizes/areas
and will be a Unique Selling Point or the stand-
out feature of the project.
Introduction & Mechanism
We built an array of phototransistors and at-
tached them to an X-Y plotter consisting of 4
rods to scan the entire target area vertically &
horizontally. Light reflected by the glass plate
on which the input object is kept is detected by
phototransistors, which then is given to the µC
for A-D conversion. It is then sent to MATLAB
by serial communication. MATLAB codes are
then used for the digitization & for mosaicing.
Our mechanism is a variation of the CIS tech-
nology presently in use.
Figure 1: Scanning mechanism
Parameters
• Speed : 15 mins for full scan of A2 (approx)
• Sensitivity : upto 5mm
• Threads of rotation (pitch) : 2mm
• Image size & resolution : User controllable
through MATLAB
• Maximum scan size : A2
Conclusion
Main advantages are ease of implementation,
Design flexibility, scope for further develop-
ments & mosaicing/extra large document scan-
ning ability. But at the same time, using pho-
totransistors involves a certain drop in perfor-
mance with respect to the speed of scanning &
output quality. Also, use of black & white scan-
ning though ideal for document scanning too re-
duces the quality due to the low bit depth &
inability to scan detailed colors.
References
[1] William D Clark. Document scanner mechanism.
IBM Journal of Research and Development, 23,
1998.
[2] R Modugno, A Ferrante, E Stasolla, and S Impe-
dovo. New trends in digital scanning processes. 10th
International Conference on Document Analysis and
Recognition, 2009.
Block Diagram
The block diagram of our project is shown in Figure 2 on the left. It shows the flow of data, from
when the scanner is first started. Stepper motors which are driven by L297 drivers are used to drive
the X-Y plotter & phototransistors act as the sensor. Then on the right, it also shows the actual
working circuit of our project.
Figure 2: Block Diagram (left); Actual working circuit (right)
Results
Scanning Results-
The scanner presently needs fairly large sized characters in order for the text to be read & identified
properly. The output scanned for the signature of one of us is as shown in the Figure 3.
Figure 3: Scanning Output
Black & white scanning is considered the most ideal for projects & documents. This is so, as the
resolution of the output image is more user controllable as compared to color scanning due to the
lesser bit depth involved. Lesser bit depth also reduces the scanner complexity thus increasing ease
of implementation. Mosaicing Results-
For testing our MATLAB mosaic code,we took the photograph of one of us & also the signature
scanned previously & split it into 2 halves.We took the 2 halved images as the input for our MATLAB
program. The end points of both the images from where they were to be stitched were selected. This
was done as shown in Figure 4. The end point selection is crucial, as improper selection can lead to
a distorted or in worst case completely wrong output. So, it is vital to precisely select the stitching
points for seamless stitching.
Figure 4: Left half input (left); Right half input (right)
After the end points are selected the 2 halves are stitched back along the designated stithing points
to give the mosaiced output. The output mosaiced image & its comparison with the actual image &
is as shown below in the Figure 5.
Similarly multiple such scans can be mosaiced together to form one final output image, which in our
case will be the output scan of the large sized document.
Figure 5: Mosaicing Output